安卓:上刷卡,而不是从一个按钮保存表单数据 [英] Android: Saving form data on a swipe rather than from a button
问题描述
我很新的Android和这是我的第二个应用程序。我正在卡式活性,其中所述第一片段具有一种形式来创建一个新的任务,所述第二片段具有的所有保存的任务列表,并在第二个从列表中选择当第三片段会显示在一个任务中的评论分段。当我点击第一个片段保存任务按钮,应用正确保存任务并显示在一个碎片的任务列表。不过,我不希望在第一个片段使用保存任务按钮。我希望能够尽快保存任务作为用户从第一活动到第二刷卡
对于这一点,我已经打过电话从 OnPageChangeListener.onPageScrolled()
方法片段的 saveTask()
方法在活动,但在片段的所有意见给予 NullPointerException异常
。如果我尝试 performClick()
从活动的 OnPageChangeListener.onPageScrollStateChanged()
,连按钮保存任务按钮给出了一个 NullPointerException异常
。当我打印到日志以查看是否保存任务按钮已经被初始化,日志正确显示按钮的ID。我在一个头绪的任务保存到使用只需刷卡数据库。请帮助!
下面是我的主要活动:
公共类AddTask扩展AppCompatActivity {/ **
*本{@link PagerAdapter},将提供
*对于每个部分的片段。我们使用
* {@link FragmentPagerAdapter}衍生,这将让每一个
*加载到内存中的片段。如果这成为太内存密集型,它
*可能是最好切换到
* {@link FragmentStatePagerAdapter}。
* /
私有静态SectionsPagerAdapter mSectionsPagerAdapter;/ **
*本{@link ViewPager}将承载部分内容。
* /
私人ViewPager mViewPager;
公开名单<串GT;碎片=新的矢量<串GT;();/ **
*注意:这是自动生成的实现应用程序索引API。
*请参阅https://g.co/AppIndexing/AndroidStudio获取更多信息。
* /
私人GoogleApiClient客户端;@覆盖
保护无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.activity_add_task); 工具条工具栏=(栏)findViewById(R.id.toolbar);
setSupportActionBar(工具栏);
//创建将返回一个片段为三个的适配器
//活性的主要部分。
mSectionsPagerAdapter =新SectionsPagerAdapter(getSupportFragmentManager()); //填充片段类碎片列表
fragments.add(AddTaskFragment.class.getName());
fragments.add(TasksFragment.class.getName());
fragments.add(CommentsFragment.class.getName()); //设置的ViewPager与部分适配器。
mViewPager =(ViewPager)findViewById(R.id.container);
mSectionsPagerAdapter =新SectionsPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setOffscreenPageLimit(2);
mViewPager.setCurrentItem(1); 最终AddTaskFragment addTaskFrag =(AddTaskFragment)mSectionsPagerAdapter.getItem(0);
mViewPager.addOnPageChangeListener(新ViewPager.OnPageChangeListener(){
@覆盖
公共无效onPageScrolled(INT位置,浮positionOffset,诠释positionOffsetPixels){
android.support.v7.app.ActionBar动作条= getSupportActionBar();
开关(位置){
情况下0:
actionBar.setTitle(添加新任务);
打破;
情况1:
actionBar.setTitle(现有任务);
打破;
案例2:
actionBar.setTitle(意见);
打破;
}
} @覆盖
公共无效使用onPageSelected(INT位置){
如果(fragments.get(位置).equals(TasksFragment.class.getName())){ }
} @覆盖
公共无效onPageScrollStateChanged(INT状态){
如果(mViewPager.getCurrentItem()== 0){
如果(状态== ViewPager.SCROLL_STATE_DRAGGING){
如果(addTaskFrag!= NULL){
addTaskFrag.saveTaskBtn.performClick();
}
}
}
}
});
//注意:这是自动生成的实现应用程序索引API。
//见https://g.co/AppIndexing/AndroidStudio获取更多信息。
客户端=新GoogleApiClient.Builder(本).addApi(AppIndex.API).build();
}
@覆盖
公共布尔onCreateOptionsMenu(菜单菜单){
//充气菜单;如果是present这增加了项目操作栏。
。getMenuInflater()膨胀(R.menu.menu_add_task,菜单);
返回true;
}@覆盖
公共布尔onOptionsItemSelected(菜单项项){
//处理动作栏项目点击这里。操作栏会
//自动处理上点击主页/向上按钮,只要
//你在AndroidManifest.xml中指定一个父活动。
INT ID = item.getItemId(); // noinspection SimplifiableIfStatement
如果(ID == R.id.action_settings){
返回true;
} 返回super.onOptionsItemSelected(项目);
}@覆盖
公共无效调用onStart(){
super.onStart(); //注意:这是自动生成的实现应用程序索引API。
//见https://g.co/AppIndexing/AndroidStudio获取更多信息。
client.connect();
行动ViewAction这一= Action.newAction(
Action.TYPE_VIEW,// TODO:选择操作类型。
AddTask页面,// TODO:定义显示的内容的标题。
// TODO:如果你有这个程序,活动的内容相匹配的网页内容,
//确保这个自动生成网页的网址是正确的。
//否则,将URL设置为null。
Uri.parse(HTTP://主机/路径),
// TODO:确保这个自动生成的应用深层链接URI是正确的。
Uri.parse(android-app://com.example.ishita.assigntasks/http/host/path)
);
AppIndex.AppIndexApi.start(客户端,ViewAction这一);
}@覆盖
公共无效的onStop(){
super.onStop();
//注意:这是自动生成的实现应用程序索引API。
//见https://g.co/AppIndexing/AndroidStudio获取更多信息。
行动ViewAction这一= Action.newAction(
Action.TYPE_VIEW,// TODO:选择操作类型。
AddTask页面,// TODO:定义显示的内容的标题。
// TODO:如果你有这个程序,活动的内容相匹配的网页内容,
//确保这个自动生成网页的网址是正确的。
//否则,将URL设置为null。
Uri.parse(HTTP://主机/路径),
// TODO:确保这个自动生成的应用深层链接URI是正确的。
Uri.parse(android-app://com.example.ishita.assigntasks/http/host/path)
);
AppIndex.AppIndexApi.end(客户端,ViewAction这一);
client.disconnect();
}/ **
* A {@link FragmentPagerAdapter}返回对应片段
*章节/标签/页面。
* /
公共类SectionsPagerAdapter扩展FragmentPagerAdapter { 公开名单<串GT; fragmentsA; 公共SectionsPagerAdapter(FragmentManager FM){
超(FM);
fragmentsA =片段;
} @覆盖
公共片段的getItem(INT位置){
//实例片段在哪里寻呼机的位置。
返回Fragment.instantiate(getApplicationContext(),fragmentsA.get(位置)); }
@覆盖
公众诠释的getCount(){
//返回多少片段中有标签式活动
返回fragmentsA.size();
} @覆盖
公众诠释getItemPosition(Object对象){
返回POSITION_NONE;
}
@覆盖
公共CharSequence的getPageTitle(INT位置){
开关(位置){
情况下0:
返回添加任务;
情况1:
返回任务清单;
案例2:
返回注释;
}
返回null;
}
}
}
这是我的片段形式的Java创建一个新的类:
/ **
*包含一个简单视图中的占位符片段。
* /
公共类AddTaskFragment扩展片段{
/ **
*片段参数重新presenting本节号
*片段。
* /
最终诠释PICK_CONTACT = 1;私有静态最后弦乐ARG_SECTION_NUMBER =SECTION_NUMBER;公共字符串mAssigneeName;
公共字符串mAssigneeContact;
公共字符串mTaskName;
公共字符串mDueDate;
公共字符串mComments = NULL;公共AddTaskFragment(){
}的EditText的dueDate;
受让人的EditText;
的EditText taskDescription;
的EditText意见;
按钮saveTaskBtn;
查看rootView;
日历myCalendar = Calendar.getInstance();DatePickerDialog.OnDateSetListener日期=新DatePickerDialog.OnDateSetListener(){ @覆盖
公共无效onDateSet(查看的DatePicker,年整型,诠释monthOfYear,
INT请将dayOfMonth){
// TODO自动生成方法存根
myCalendar.set(Calendar.YEAR,年);
myCalendar.set(的Calendar.MONTH,monthOfYear);
myCalendar.set(Calendar.DAY_OF_MONTH,请将dayOfMonth);
updateLabel();
}};私人无效updateLabel(){ 字符串displayFormat =MMM DD,YYYY //设置在该日期将显示格式
SimpleDateFormat的SDF =新的SimpleDateFormat(displayFormat,Locale.US); dueDate.setText(sdf.format(myCalendar.getTime()));
}/ **
*返回该片段的一个新实例为给定的部
*号。
* /
公共静态的newInstance AddTaskFragment(INT sectionNumber){
AddTaskFragment片段=新AddTaskFragment();
捆绑ARGS =新包();
args.putInt(ARG_SECTION_NUMBER,sectionNumber);
fragment.setArguments(参数);
返回片段;
}@覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,
捆绑savedInstanceState){
rootView = inflater.inflate(R.layout.fragment_add_task,集装箱,FALSE); 的dueDate =(EditText上)rootView.findViewById(R.id.due_date);
taskDescription =(EditText上)rootView.findViewById(R.id.description);
评论=(EditText上)rootView.findViewById(R.id.comments);
受让人=(EditText上)rootView.findViewById(R.id.assignee); dueDate.setOnClickListener(新View.OnClickListener(){ @覆盖
公共无效的onClick(视图v){
新DatePickerDialog(getActivity(),日期,myCalendar
获得(Calendar.YEAR),myCalendar.get(的Calendar.MONTH)
。myCalendar.get(Calendar.DAY_OF_MONTH))显示();
}
} ); assignee.setOnClickListener(新View.OnClickListener(){
@覆盖
公共无效的onClick(视图v){
尝试{
意向意图=新意图(Intent.ACTION_PICK);
intent.setType(ContactsContract.CommonDataKinds.Phone.CONTENT_TYPE);
startActivityForResult(意向,PICK_CONTACT);
}赶上(例外五){
e.printStackTrace();
}
}
}); saveTaskBtn =(按钮)rootView.findViewById(R.id.save_task);
Log.v(AddTaskFragment,saveTaskBtn分配给+ R.id.save_task);
saveTaskBtn.setOnClickListener(新View.OnClickListener(){
@覆盖
公共无效的onClick(视图v){
saveTask();
}
}); 返回rootView;
}公共无效saveTask(){
尝试{
mTaskName = taskDescription.getText()的toString()。
taskDescription.setText();
。mDueDate = dueDate.getText()的toString();
dueDate.setText();
mComments = comments.getText()的toString()。
comments.setText();
assignee.setText(R.string.assignee_prompt);
如果(mTaskName == NULL || mDueDate == NULL || mAssigneeName == NULL){
Toast.makeText(的getContext()。字段不能为空,请填写一些值,Toast.LENGTH_SHORT).show();
}其他{
UpdateTask数据库更新=新UpdateTask();
updateDB.execute();
Toast.makeText(的getContext(),任务得救了。Toast.LENGTH_SHORT).show();
}
}赶上(例外五){
e.printStackTrace();
}
}公共无效的onActivityResult(INT REQ code,INT结果code,意图数据){
super.onActivityResult(REQ code,结果code,数据);
受让人的EditText =(EditText上)getActivity()findViewById(R.id.assignee)。
开关(REQ code){
案例(PICK_CONTACT):
如果(结果code == Activity.RESULT_OK){
乌里联络资料= data.getData();
光标光标=的getContext()。getContentResolver()查询(联络资料,新的String [] {ContactsContract.CommonDataKinds.Phone._ID,ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME,ContactsContract.CommonDataKinds.Phone.NUMBER},NULL,NULL,NULL ); 如果(cursor.moveToFirst()){
mAssigneeName = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
mAssigneeContact = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone.NUMBER));
assignee.setText(mAssigneeName);
Toast.makeText(getActivity(),mAssigneeName +有号+ mAssigneeContact,Toast.LENGTH_LONG).show();
}
cursor.close();
}
打破;
}}公共类UpdateTask扩展的AsyncTask<太虚,太虚,太虚> { 保护无效doInBackground(虚空...... PARAMS){
ContentValues taskDetails =新ContentValues();
taskDetails.put(TasksContract.TaskEntry.COL_DESCRIPTION,mTaskName);
taskDetails.put(TasksContract.TaskEntry.COL_ASSIGNEE_KEY,mAssigneeContact);
taskDetails.put(TasksContract.TaskEntry.COL_CREATOR_KEY的creatorID);
taskDetails.put(TasksContract.TaskEntry.COL_DUE_DATE,mDueDate);
taskDetails.put(TasksContract.TaskEntry.COL_COMMENTS,mComments); 。的getContext()getContentResolver()插入(TasksContract.TaskEntry.CONTENT_URI,taskDetails)。 光标光标=的getContext()。getContentResolver()查询(
TasksContract.ProfileEntry.CONTENT_URI,
新的String [] {} TasksContract.ProfileEntry._ID,
TasksContract.ProfileEntry.COL_CONTACT +=?,
新的String [] {} mAssigneeContact,
空值
);
如果(!cursor.moveToFirst()){
ContentValues contactDetails =新ContentValues();
contactDetails.put(TasksContract.ProfileEntry.COL_NAME,mAssigneeName);
contactDetails.put(TasksContract.ProfileEntry.COL_CONTACT,mAssigneeContact); 。的getContext()getContentResolver()插入(TasksContract.ProfileEntry.CONTENT_URI,contactDetails);
}
cursor.close();
返回null;
}
}}
这是XML的片段:
<滚动型的xmlns:机器人=http://schemas.android.com/apk/res/android
的xmlns:工具=http://schemas.android.com/tools
机器人:layout_width =match_parent
机器人:layout_height =match_parent><的LinearLayout
机器人:layout_width =match_parent
机器人:layout_height =WRAP_CONTENT
机器人:方向=垂直
机器人:paddingBottom会=@扪/ activity_vertical_margin
机器人:paddingLeft =@扪/ activity_horizontal_margin
机器人:paddingRight =@扪/ activity_horizontal_margin
机器人:paddingTop =@扪/ activity_vertical_margin
工具:上下文=com.example.ishita.assigntasks.AddTaskFragment> <的EditText
机器人:ID =@ + ID /说明
机器人:layout_width =match_parent
机器人:layout_height =WRAP_CONTENT
机器人:layout_margin =10dp
机器人:提示=@字符串/ task_prompt/> <的EditText
机器人:ID =@ + ID /受让人
机器人:layout_width =match_parent
机器人:layout_height =WRAP_CONTENT
机器人:layout_margin =10dp
机器人:EMS =10
机器人:可聚焦=假
安卓的inputType =textPersonName
机器人:文字=@字符串/ assignee_prompt/> <的LinearLayout
机器人:layout_width =match_parent
机器人:layout_height =WRAP_CONTENT
机器人:layout_margin =10dp
机器人:方向=横向> <的TextView
机器人:ID =@ + ID /日期
机器人:layout_width =WRAP_CONTENT
机器人:layout_height =WRAP_CONTENT
机器人:layout_weight =1
机器人:文字=@字符串/ DUE_DATE
机器人:TEXTSIZE =18sp/> <的EditText
机器人:ID =@ + ID / DUE_DATE
机器人:layout_width =WRAP_CONTENT
机器人:layout_height =WRAP_CONTENT
机器人:layout_weight =2
机器人:EMS =10
机器人:可聚焦=假
安卓的inputType =日期/> < / LinearLayout中> <的EditText
机器人:ID =@ + ID /评论
机器人:layout_width =match_parent
机器人:layout_height =WRAP_CONTENT
机器人:layout_margin =10dp
机器人:提示=@字符串/注释
安卓了minHeight =:/>中的Android清单preferredItemHeight? <按钮
机器人:ID =@ + ID / save_task
机器人:layout_width =WRAP_CONTENT
机器人:layout_height =WRAP_CONTENT
机器人:layout_gravity =CENTER_HORIZONTAL
机器人:文字=@字符串/ save_task/>
< / LinearLayout中>
< /滚动型>
LogCat中:
02-18 13:48:05.538 3752-3752 /? I /艺术:晚启用-Xcheck:JNI
02-18 13:48:05.628 3752-3752 / com.example.ishita.assigntasks W /的ResourceType:找到多个库表,无视...
02-18 13:48:05.664 3752-3752 / com.example.ishita.assigntasks I / GMPM:测量应用程序启动时,版本:8487
02-18 13:48:05.664 3752-3752 / com.example.ishita.assigntasks I / GMPM:启用调试日志记录运行:亚行外壳setprop log.tag.GMPM VERBOSE
02-18 13:48:05.823 3752-3788 / com.example.ishita.assigntasks D / OpenGLRenderer:使用EGL_SWAP_BEHAVIOR_ preSERVED:真
02-18 13:48:05.840 3752-3752 / com.example.ishita.assigntasks D /图集:验证地图...
02-18 13:48:06.039 3752-3788 / com.example.ishita.assigntasks I /肾上腺EGL:其中,qeglDrvAPI_eglInitialize:410计算值:1.4 EGL构建QUALCOMM:AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.01.00.042.030_msm8974_LA .BF.1.1.1_RB1__release_AU()
OpenGL ES的着色器编译器版本:E031.25.03.06
生成日期:15年5月17日太阳
当地分公司:mybranch10089422
远程分支:QUIC / LA.BF.1.1.1_rb1.22
局部修补程序:否
重建分公司:AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.01.00.042.030 + 6151be1 + NOTHING
02-18 13:48:06.053 3752-3788 / com.example.ishita.assigntasks I / OpenGLRenderer:初始化EGL,1.4版本
02-18 13:48:06.077 3752-3788 / com.example.ishita.assigntasks D / OpenGLRenderer:启用调试模式0
02-18 13:48:06.123 3752-3752 / com.example.ishita.assigntasks W /查看:requestLayout()由android.widget.TextView不当称为{5fbdde1 V.ED .... ...... ID 48,43-403,124}布局中:运行第二布局传递
02-18 13:48:06.440 3752-3752 / com.example.ishita.assigntasks V /案例:MSGCOUNT:调用getInt:0
02-18 13:48:06.440 3752-3752 / com.example.ishita.assigntasks V / getViewId:2131493003
02-18 13:48:06.485 3752-3752 / com.example.ishita.assigntasks I /时间轴:时间轴:Activity_idle ID:android.os.BinderProxy@9dab03c时间:19983548
02-18 13:48:10.458 3752-3752 / com.example.ishita.assigntasks E / InputEventReceiver:异常调度输入事件。
02-18 13:48:10.458 3752-3752 / com.example.ishita.assigntasks D / AndroidRuntime:关闭VM
02-18 13:48:10.532 3752-3752 / com.example.ishita.assigntasks E / AndroidRuntime:致命异常:主要
工艺:com.example.ishita.assigntasks,PID:3752
显示java.lang.NullPointerException:尝试调用虚方法对空对象引用布尔android.widget.Button.performClick()
在com.example.ishita.assigntasks.AddTask $ 1.onPageScrollStateChanged(AddTask.java:100)
在android.support.v4.view.ViewPager.dispatchOnScrollStateChanged(ViewPager.java:1811)
在android.support.v4.view.ViewPager.setScrollState(ViewPager.java:404)
在android.support.v4.view.ViewPager.onInterceptTouchEvent(ViewPager.java:1935)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1961)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
在android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
在com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2372)
在com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1722)
在android.app.Activity.dispatchTouchEvent(Activity.java:2742)
在android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
在android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
在com.android.internal.policy.impl.PhoneWindow $ DecorView.dispatchTouchEvent(PhoneWindow.java:2333)
在android.view.View.dispatchPointerEvent(View.java:8742)
在android.view.ViewRootImpl $ ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4136)
在android.view.ViewRootImpl $ ViewPostImeInputStage.onProcess(ViewRootImpl.java:4002)
在android.view.ViewRootImpl $ InputStage.deliver(ViewRootImpl.java:3557)
在android.view.ViewRootImpl $ InputStage.onDeliverToNext(ViewRootImpl.java:3610)
在android.view.ViewRootImpl $ InputStage.forward(ViewRootImpl.java:3576)
在android.view.ViewRootImpl $ AsyncInputStage.forward(ViewRootImpl.java:3693)
在android.view.ViewRootImpl $ InputStage.apply(ViewRootImpl.java:3584)
在android.view.ViewRootImpl $ AsyncInputStage.apply(ViewRootImpl.java:3750)
在android.view.ViewRootImpl $ InputStage.deliver(ViewRootImpl.java:3557)
在android.view.ViewRootImpl $ InputStage.onDeliverToNext(ViewRootImpl.java:3610)
在android.view.ViewRootImpl $ InputStage.forward(ViewRootImpl.java:3576)
在android.view.ViewRootImpl $ InputStage.apply(ViewRootImpl.java:3584)
在android.view.ViewRootImpl $ InputStage.deliver(ViewRootImpl.java:3557)
在android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5823)
在android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5797)
在android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5768)
在android.view.ViewRootImpl $ WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5913)
在android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
在android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(本机方法)
在android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
在android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:5884)
在android.view.ViewRootImpl $ ConsumeBatchedInputRunnable.run(ViewRootImpl.java:5936)
在android.view.Choreographer $ CallbackRecord.run(Choreographer.java:767)
在android.view.Choreographer.doCallbacks(Choreographer.java:580)
在android.view.Choreographer.doFrame(Choreographer.java:548)
在 OnPageChangeListener
是一个网页变化被调用的方法(在另一页被选中)使用onPageSelected
。
此外,调用的getItem
在 PagerAdapter
实例化一个新的片段。为了解决这个问题,你需要保持你的片段的一个列表,你PagerAdapter并创建一个方法来检索他们。
//在PagerAdapter:
私人列表<片断> fragmentList;公共SectionsPagerAdapter(FragmentManager FM){
超(FM);
fragmentsA =片段;
fragmentList =新的ArrayList<片断>(); 的for(int i = 0;我3;;我++){
fragmentList.add(Fragment.instantiate(getApplicationContext(),fragmentsA.get(ⅰ)));
}
}公共片段getFragment(INT位置){ 返回fragmentList.get(位置);
}
I am very new to android and this is my second app. I am making a tabbed activity where the first fragment has a form to create a new task, the second fragment has the list of all the saved tasks, and the third fragment will show the comments on a task when selected from the list in the second fragment. When I click on the Save Task button on the first fragment, the app correctly saves the task and shows it in the list of tasks in the next fragment. However, I don't want to use a "Save Task" button in the first fragment. I want to be able to save the task as soon as the user swipes from the first activity to the second.
For this, I have tried calling the fragment's saveTask()
method from the OnPageChangeListener.onPageScrolled()
method in the activity, but all the views in the fragment give a NullPointerException
. If I try to performClick()
on the Save Task button from the activity's OnPageChangeListener.onPageScrollStateChanged()
, even the button gives a NullPointerException
. When I print to the log to see if the Save Task button has been initialized, the log correctly shows the button ID. I am at a loss as to how to save the task to the database using just a swipe. Please help!
Here is my main activity:
public class AddTask extends AppCompatActivity {
/**
* The {@link PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {@link FragmentStatePagerAdapter}.
*/
private static SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
public List<String> fragments = new Vector<String>();
/**
* ATTENTION: This was auto-generated to implement the App Indexing API.
* See https://g.co/AppIndexing/AndroidStudio for more information.
*/
private GoogleApiClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_task);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
//fill the fragments list with the fragment classes
fragments.add(AddTaskFragment.class.getName());
fragments.add(TasksFragment.class.getName());
fragments.add(CommentsFragment.class.getName());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setOffscreenPageLimit(2);
mViewPager.setCurrentItem(1);
final AddTaskFragment addTaskFrag = (AddTaskFragment) mSectionsPagerAdapter.getItem(0);
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
android.support.v7.app.ActionBar actionBar = getSupportActionBar();
switch (position) {
case 0:
actionBar.setTitle("Add New Task");
break;
case 1:
actionBar.setTitle("Existing Tasks");
break;
case 2:
actionBar.setTitle("Comments");
break;
}
}
@Override
public void onPageSelected(int position) {
if (fragments.get(position).equals(TasksFragment.class.getName())) {
}
}
@Override
public void onPageScrollStateChanged(int state) {
if(mViewPager.getCurrentItem()==0) {
if (state == ViewPager.SCROLL_STATE_DRAGGING) {
if (addTaskFrag != null) {
addTaskFrag.saveTaskBtn.performClick();
}
}
}
}
});
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_add_task, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onStart() {
super.onStart();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
client.connect();
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"AddTask Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.ishita.assigntasks/http/host/path")
);
AppIndex.AppIndexApi.start(client, viewAction);
}
@Override
public void onStop() {
super.onStop();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"AddTask Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.ishita.assigntasks/http/host/path")
);
AppIndex.AppIndexApi.end(client, viewAction);
client.disconnect();
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public List<String> fragmentsA;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
fragmentsA = fragments;
}
@Override
public Fragment getItem(int position) {
//Instantiate the fragment at the position where the pager is.
return Fragment.instantiate(getApplicationContext(), fragmentsA.get(position));
}
@Override
public int getCount() {
// return how many fragments there are in the tabbed activity
return fragmentsA.size();
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Add Task";
case 1:
return "Tasks List";
case 2:
return "Comments";
}
return null;
}
}
}
And here is my fragment form Java for creating a new class:
/**
* A placeholder fragment containing a simple view.
*/
public class AddTaskFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
final int PICK_CONTACT = 1;
private static final String ARG_SECTION_NUMBER = "section_number";
public String mAssigneeName;
public String mAssigneeContact;
public String mTaskName;
public String mDueDate;
public String mComments = null;
public AddTaskFragment() {
}
EditText dueDate;
EditText assignee;
EditText taskDescription;
EditText comments;
Button saveTaskBtn;
View rootView;
Calendar myCalendar = Calendar.getInstance();
DatePickerDialog.OnDateSetListener date = new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
// TODO Auto-generated method stub
myCalendar.set(Calendar.YEAR, year);
myCalendar.set(Calendar.MONTH, monthOfYear);
myCalendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
updateLabel();
}
};
private void updateLabel() {
String displayFormat = "MMM dd, yyyy"; //setting the format in which the date will be displayed
SimpleDateFormat sdf = new SimpleDateFormat(displayFormat, Locale.US);
dueDate.setText(sdf.format(myCalendar.getTime()));
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static AddTaskFragment newInstance(int sectionNumber) {
AddTaskFragment fragment = new AddTaskFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_add_task, container, false);
dueDate = (EditText) rootView.findViewById(R.id.due_date);
taskDescription = (EditText) rootView.findViewById(R.id.description);
comments = (EditText) rootView.findViewById(R.id.comments);
assignee = (EditText) rootView.findViewById(R.id.assignee);
dueDate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new DatePickerDialog(getActivity(), date, myCalendar
.get(Calendar.YEAR), myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH)).show();
}
}
);
assignee.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType(ContactsContract.CommonDataKinds.Phone.CONTENT_TYPE);
startActivityForResult(intent, PICK_CONTACT);
} catch (Exception e) {
e.printStackTrace();
}
}
});
saveTaskBtn = (Button) rootView.findViewById(R.id.save_task);
Log.v("AddTaskFragment", "saveTaskBtn assigned to " + R.id.save_task);
saveTaskBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
saveTask();
}
});
return rootView;
}
public void saveTask(){
try {
mTaskName = taskDescription.getText().toString();
taskDescription.setText("");
mDueDate = dueDate.getText().toString();
dueDate.setText("");
mComments = comments.getText().toString();
comments.setText("");
assignee.setText(R.string.assignee_prompt);
if (mTaskName == null || mDueDate == null || mAssigneeName == null) {
Toast.makeText(getContext(), "Fields cannot be empty. Please fill some values.", Toast.LENGTH_SHORT).show();
} else {
UpdateTask updateDB = new UpdateTask();
updateDB.execute();
Toast.makeText(getContext(), "Task saved.", Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void onActivityResult(int reqCode, int resultCode, Intent data) {
super.onActivityResult(reqCode, resultCode, data);
EditText assignee = (EditText) getActivity().findViewById(R.id.assignee);
switch (reqCode) {
case (PICK_CONTACT):
if (resultCode == Activity.RESULT_OK) {
Uri contactData = data.getData();
Cursor cursor = getContext().getContentResolver().query(contactData, new String[]{ContactsContract.CommonDataKinds.Phone._ID, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME, ContactsContract.CommonDataKinds.Phone.NUMBER}, null, null, null);
if (cursor.moveToFirst()) {
mAssigneeName = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
mAssigneeContact = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone.NUMBER));
assignee.setText(mAssigneeName);
Toast.makeText(getActivity(), mAssigneeName + " has number " + mAssigneeContact, Toast.LENGTH_LONG).show();
}
cursor.close();
}
break;
}
}
public class UpdateTask extends AsyncTask<Void, Void, Void> {
protected Void doInBackground(Void... params) {
ContentValues taskDetails = new ContentValues();
taskDetails.put(TasksContract.TaskEntry.COL_DESCRIPTION, mTaskName);
taskDetails.put(TasksContract.TaskEntry.COL_ASSIGNEE_KEY, mAssigneeContact);
taskDetails.put(TasksContract.TaskEntry.COL_CREATOR_KEY, "creatorID");
taskDetails.put(TasksContract.TaskEntry.COL_DUE_DATE, mDueDate);
taskDetails.put(TasksContract.TaskEntry.COL_COMMENTS, mComments);
getContext().getContentResolver().insert(TasksContract.TaskEntry.CONTENT_URI, taskDetails);
Cursor cursor = getContext().getContentResolver().query(
TasksContract.ProfileEntry.CONTENT_URI,
new String[]{TasksContract.ProfileEntry._ID},
TasksContract.ProfileEntry.COL_CONTACT + "=?",
new String[]{mAssigneeContact},
null
);
if (!cursor.moveToFirst()) {
ContentValues contactDetails = new ContentValues();
contactDetails.put(TasksContract.ProfileEntry.COL_NAME, mAssigneeName);
contactDetails.put(TasksContract.ProfileEntry.COL_CONTACT, mAssigneeContact);
getContext().getContentResolver().insert(TasksContract.ProfileEntry.CONTENT_URI, contactDetails);
}
cursor.close();
return null;
}
}
}
And here is the XML for the fragment:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.ishita.assigntasks.AddTaskFragment">
<EditText
android:id="@+id/description"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:hint="@string/task_prompt" />
<EditText
android:id="@+id/assignee"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:ems="10"
android:focusable="false"
android:inputType="textPersonName"
android:text="@string/assignee_prompt" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:orientation="horizontal">
<TextView
android:id="@+id/date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/due_date"
android:textSize="18sp" />
<EditText
android:id="@+id/due_date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="2"
android:ems="10"
android:focusable="false"
android:inputType="date" />
</LinearLayout>
<EditText
android:id="@+id/comments"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:hint="@string/comments"
android:minHeight="?android:listPreferredItemHeight" />
<Button
android:id="@+id/save_task"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/save_task" />
</LinearLayout>
</ScrollView>
LogCat:
02-18 13:48:05.538 3752-3752/? I/art: Late-enabling -Xcheck:jni
02-18 13:48:05.628 3752-3752/com.example.ishita.assigntasks W/ResourceType: Found multiple library tables, ignoring...
02-18 13:48:05.664 3752-3752/com.example.ishita.assigntasks I/GMPM: App measurement is starting up, version: 8487
02-18 13:48:05.664 3752-3752/com.example.ishita.assigntasks I/GMPM: To enable debug logging run: adb shell setprop log.tag.GMPM VERBOSE
02-18 13:48:05.823 3752-3788/com.example.ishita.assigntasks D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
02-18 13:48:05.840 3752-3752/com.example.ishita.assigntasks D/Atlas: Validating map...
02-18 13:48:06.039 3752-3788/com.example.ishita.assigntasks I/Adreno-EGL: <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.01.00.042.030_msm8974_LA.BF.1.1.1_RB1__release_AU ()
OpenGL ES Shader Compiler Version: E031.25.03.06
Build Date: 05/17/15 Sun
Local Branch: mybranch10089422
Remote Branch: quic/LA.BF.1.1.1_rb1.22
Local Patches: NONE
Reconstruct Branch: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.01.00.042.030 + 6151be1 + NOTHING
02-18 13:48:06.053 3752-3788/com.example.ishita.assigntasks I/OpenGLRenderer: Initialized EGL, version 1.4
02-18 13:48:06.077 3752-3788/com.example.ishita.assigntasks D/OpenGLRenderer: Enabling debug mode 0
02-18 13:48:06.123 3752-3752/com.example.ishita.assigntasks W/View: requestLayout() improperly called by android.widget.TextView{5fbdde1 V.ED.... ......ID 48,43-403,124} during layout: running second layout pass
02-18 13:48:06.440 3752-3752/com.example.ishita.assigntasks V/case:msgCount:getInt: 0
02-18 13:48:06.440 3752-3752/com.example.ishita.assigntasks V/getViewId: 2131493003
02-18 13:48:06.485 3752-3752/com.example.ishita.assigntasks I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@9dab03c time:19983548
02-18 13:48:10.458 3752-3752/com.example.ishita.assigntasks E/InputEventReceiver: Exception dispatching input event.
02-18 13:48:10.458 3752-3752/com.example.ishita.assigntasks D/AndroidRuntime: Shutting down VM
02-18 13:48:10.532 3752-3752/com.example.ishita.assigntasks E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ishita.assigntasks, PID: 3752
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.widget.Button.performClick()' on a null object reference
at com.example.ishita.assigntasks.AddTask$1.onPageScrollStateChanged(AddTask.java:100)
at android.support.v4.view.ViewPager.dispatchOnScrollStateChanged(ViewPager.java:1811)
at android.support.v4.view.ViewPager.setScrollState(ViewPager.java:404)
at android.support.v4.view.ViewPager.onInterceptTouchEvent(ViewPager.java:1935)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1961)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2406)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2107)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2372)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1722)
at android.app.Activity.dispatchTouchEvent(Activity.java:2742)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2333)
at android.view.View.dispatchPointerEvent(View.java:8742)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4136)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4002)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3557)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3610)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3576)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3693)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3584)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3750)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3557)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3610)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3576)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3584)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3557)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5823)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5797)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5768)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5913)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:5884)
at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:5936)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:548)
The invoked method for a page change(when another page gets selected) in your OnPageChangeListener
is onPageSelected
.
Also, calling getItem
on your PagerAdapter
instantiates a new Fragment. To solve this problem, you'll need to keep a List of your Fragments in your PagerAdapter and create a method to retrieve them.
//in PagerAdapter:
private List<Fragment> fragmentList;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
fragmentsA = fragments;
fragmentList = new ArrayList<Fragment>();
for(int i = 0; i < 3; i++){
fragmentList.add(Fragment.instantiate(getApplicationContext(), fragmentsA.get(i)););
}
}
public Fragment getFragment(int position){
return fragmentList.get(position);
}
这篇关于安卓:上刷卡,而不是从一个按钮保存表单数据的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!