为什么我不能在Android中使用SimpleAdapter在ListView中单击按钮? [英] Why can't I click a Button in a ListView using SimpleAdapter in android?
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问题描述
我是 Android 的新手.我也早些时候发布了这个问题，但是没有找到合适的答案.我的要求是在使用 SimpleAdapter 生成的 Listview 中使一个 Button 可单击.我不想使用 CustomAdapter， BaseAdapter 或任何其他适配器.我不想将Activty扩展为 SimpleAdapter .我的代码和错误日志如下.如果有人有任何解决方案，请逐步向我解释.谢谢.
I am a newbie to Android. I have posted this question earlier too but didn't find the appropriate answer. My requirement is to make a Button clickable in a Listviewwhich is generated using a SimpleAdapter.I don't want to use CustomAdapter,BaseAdapter or any other Adapter. I don't want to extend my Activty as SimpleAdapter.My code and error logs are as follows. If anyone has any solutions please explain to me step by step. Thank you.
MainActivity.java
MainActivity.java
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<HashMap<String, String>>val1=new ArrayList<HashMap<String,String>>();
HashMap<String, String>val=new HashMap<String,String>();
val.put("a","a");
val.put("c","c");
val.put("b","b");
val1.add(val);
final ListView l=(ListView)findViewById(R.id.listView1);
ListAdapter k=new SimpleAdapter(this,val1,R.layout.mytask,new String[]{"TaskId","heading","status"},new int[]{R.id.View1,R.id.View2,R.id.ViewStatus});
Button b=(Button)findViewById(R.id.mytask);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Toast.makeText(MainActivity.this,"save",Toast.LENGTH_SHORT).show();
}
});
l.setAdapter(k);
}
错误日志:
04-07 01:43:07.075: E/AndroidRuntime(2113): FATAL EXCEPTION: main
04-07 01:43:07.075: E/AndroidRuntime(2113): Process: com.example.s, PID: 2113
04-07 01:43:07.075: E/AndroidRuntime(2113): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.s/com.example.s.MainActivity}: java.lang.NullPointerException
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.os.Handler.dispatchMessage(Handler.java:102)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.os.Looper.loop(Looper.java:136)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-07 01:43:07.075: E/AndroidRuntime(2113): at java.lang.reflect.Method.invokeNative(Native Method)
04-07 01:43:07.075: E/AndroidRuntime(2113): at java.lang.reflect.Method.invoke(Method.java:515)
04-07 01:43:07.075: E/AndroidRuntime(2113): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-07 01:43:07.075: E/AndroidRuntime(2113): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-07 01:43:07.075: E/AndroidRuntime(2113): at dalvik.system.NativeStart.main(Native Method)
04-07 01:43:07.075: E/AndroidRuntime(2113): Caused by: java.lang.NullPointerException
04-07 01:43:07.075: E/AndroidRuntime(2113): at com.example.s.MainActivity.onCreate(MainActivity.java:34)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.Activity.performCreate(Activity.java:5231)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-07 01:43:07.075: E/AndroidRuntime(2113): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-07 01:43:07.075: E/AndroidRuntime(2113): ... 11 more
mytask.xml
mytask.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="18dp"
android:text="Task Name:"
android:textSize="15dp"
android:textStyle="bold" />
<TextView
android:id="@+id/View1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="TextView"
android:textSize="15dp"
android:textStyle="bold"
android:visibility="invisible" />
<TextView
android:id="@+id/View2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/textView1"
android:layout_alignBottom="@+id/textView1"
android:layout_marginLeft="31dp"
android:layout_toRightOf="@+id/textView1"
android:text="TextView"
android:textSize="15dp"
android:textStyle="bold"
android:visibility="visible" />
<TextView
android:id="@+id/ViewStatus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/View2"
android:layout_alignBottom="@+id/View2"
android:layout_alignParentRight="true"
android:text="Pending"
android:textSize="15dp"
android:textStyle="bold" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/ViewStatus"
android:layout_alignBottom="@+id/ViewStatus"
android:layout_marginRight="14dp"
android:layout_toLeftOf="@+id/ViewStatus"
android:text="Status:"
android:textSize="15dp"
android:textStyle="bold" />
<Button
android:id="@+id/mytask"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/textView1"
android:text="Button" />
</RelativeLayout>
activity_main.xml
activity_main.xml
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="106dp"
android:layout_marginTop="124dp" >
</ListView>
推荐答案
activity_main.xml 没有 ID 为 mytask 的 Button.因此，您无法在MainActivtiy中初始化Button.
activity_main.xml does not have Button with id mytask. So you cannot initialize Button in MainActivtiy.
Button 属于 mytask.xml 覆盖getView并在其中具有按钮侦听器.
The Button belongs to mytask.xml override getView and have the button listener there.
http://developer.android.com/reference/android/widget/SimpleAdapter.html
SimpleAdapter k=new SimpleAdapter(this,val1,R.layout.mytask,new String[]{"a","c","b"},new int[]{R.id.View1,R.id.View2,R.id.ViewStatus})
{
@Override
public View getView (int position, View convertView, ViewGroup parent)
{
View v = super.getView(position, convertView, parent);
Button b=(Button)v.findViewById(R.id.mytask);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Toast.makeText(MainActivity.this,"save",Toast.LENGTH_SHORT).show();
}
});
return v;
}
};
由于您不相信这很简单
这篇关于为什么我不能在Android中使用SimpleAdapter在ListView中单击按钮?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！
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