如何从一个活动引用片段的方法呢？ [英] How to reference a fragment's methods from an activity?
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问题描述
我有，我有3个片段工作的一个viewpager应用程序。
![](\"http://i.stack.imgur.com/Y5CbB.png\")
公共类ViewPagerAdapter扩展FragmentStatePagerAdapter {CharSequence的标题[]; //这将存储的选项卡这将会创建ViewPagerAdapter时传递的标题
INT NumbOfTabs; //存储标签的数量，创建ViewPagerAdapter若这也将被传递
//建立一个构造函数和分配的值传递给适当的值在类
公共ViewPagerAdapter（FragmentManager FM，CharSequence的mTitles []，诠释mNumbOfTabsumb）{
超（FM）; this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;}//此方法返回的片段在查看传呼机的每个位置
@覆盖
公共片段的getItem（INT位置）{ 如果（位置== 0）//如果位置是0，我们正在返回的第一个选项卡
{
Current_forecast_fragment current_forecast_fragment =新Current_forecast_fragment（）;
返回current_forecast_fragment;
}
否则，如果（位置== 1）//因为我们有2个选项卡，如果现在的位置是0它必须是1，所以我们正在返回第二个标签
{
返回新Hourly_forecast_fragment（）;
}其他{
返回新Daily_forecast_fragment（）;
}}//此方法返回的标题为标签在标签栏@覆盖
公共CharSequence的getPageTitle（INT位置）{
回到标题[位置]
}//此方法返回标签的数量的标签条@覆盖
公众诠释的getCount（）{
返回NumbOfTabs;
}
}
我如何引用片段，可以说从我的主要活动根据目前的预测呢？我想类似的东西，但我需要的片段ID来引用它。有什么建议？
公共类MainActivity扩展AppCompatActivity {
ViewPager寻呼机;
ViewPagerAdapter适配器;
SlidingTabLayout标签;
CharSequence的标题[] = {当前，每小时，人民日报};
INT Numboftabs = 3;
Current_forecast_fragment mCurrent_forecast_fragment;公共静态最后的字符串标记= MainActivity.class.getSimpleName（）;
公共静态最后弦乐LOCATION_KEY =location_key;
公共预测mForecast;
公共静态最后弦乐DAILY_FORECAST =DAILY_FORECAST;
公共静态最后弦乐HOURLY_FORECAST =HOURLY_FORECAST;
//默认坐标 - 戈采代尔切夫，英国拉逖：57.156866;长：
私人双重纬度= 41.5667;
私人双人经度= 23.7333;
私人的LocationManager的LocationManager;
@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_main）;
// -----------我的code从这里开始----------------- mCurrent_forecast_fragment =（Current_forecast_fragment）getSupportFragmentManager（）findFragmentById（R.id ??????）;
//Log.d（MainActivity，mCurrent_forecast_fragment.getTag（）+的Georgi）;
的getLocation（）; //创建ViewPagerAdapter和传递段管理器，光纤收发器的标题标签和数目的标签。
适配器=新ViewPagerAdapter（getSupportFragmentManager（），标题，Numboftabs）; //分配ViewPager查看和设置适配器
寻呼机=（ViewPager）findViewById（R.id.pager）;
pager.setAdapter（适配器）; // Assiging滑动标签布局视图
标签=（SlidingTabLayout）findViewById（R.id.tabs）;
tabs.setDistributeEvenly（真）; //为了使固定设置这个真实的标签，这让标签间距相等的有效幅宽 //设置自定义颜色的标签视图的滚动栏
tabs.setCustomTabColorizer（新SlidingTabLayout.TabColorizer（）{
@覆盖
公众诠释getIndicatorColor（INT位置）{
返回getResources（）的getColor（R.color.tabsScrollColor）。
}
}）; //设置ViewPager对于SlidingTabsLayout
tabs.setViewPager（寻呼机）;
}
}
解决方案
很多实验我来用一个简单的解决我的问题后。由于我在XML动态（在viewPagerAdapter），并且不添加片段我不能用ID或标签引用它们weither。我的解决方案，使其存储作为参数传递的片段的引用稍微修改适配器。然后，所有的片段的方法可访问在MainActivity（如果declired公共）：
MainActivity：
公共类MainActivity扩展AppCompatActivity {
ViewPager寻呼机;
ViewPagerAdapter适配器;
SlidingTabLayout标签;
CharSequence的标题[] = {当前，每小时，人民日报};
INT Numboftabs = 3;
Current_forecast_fragment mCurrent_forecast_fragment;@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_main）;
// -----------我的code从这里开始-----------------
this.mCurrent_forecast_fragment =新Current_forecast_fragment（）; //创建ViewPagerAdapter和传递段管理器，光纤收发器的标题标签和数目的标签。
适配器=新ViewPagerAdapter（getSupportFragmentManager（），标题，Numboftabs，mCurrent_forecast_fragment）; //分配ViewPager查看和设置适配器
寻呼机=（ViewPager）findViewById（R.id.pager）;
pager.setOffscreenPageLimit（3）;
pager.setAdapter（适配器）; // Assiging滑动标签布局视图
标签=（SlidingTabLayout）findViewById（R.id.tabs）;
tabs.setDistributeEvenly（真）; //为了使固定设置这个真实的标签，这让标签间距相等的有效幅宽 //设置自定义颜色的标签视图的滚动栏
tabs.setCustomTabColorizer（新SlidingTabLayout.TabColorizer（）{
@覆盖
公众诠释getIndicatorColor（INT位置）{
返回getResources（）的getColor（R.color.tabsScrollColor）。
}
}）; //设置ViewPager对于SlidingTabsLayout
tabs.setViewPager（寻呼机）;
}
我的code在ViewPagerAdapter：
公共类ViewPagerAdapter扩展FragmentStatePagerAdapter {
私人Current_forecast_fragment mCurrent_forecast_fragment;
CharSequence的标题[]; //这将存储的选项卡这将会创建ViewPagerAdapter时传递的标题
INT NumbOfTabs; //存储标签的数量，创建ViewPagerAdapter若这也将被传递
//建立一个构造函数和分配的值传递给适当的值在类
公共ViewPagerAdapter（FragmentManager FM，CharSequence的mTitles []，INT mNumbOfTabsumb，Current_forecast_fragment current_fragment）{
超（FM）;
this.mCurrent_forecast_fragment = current_fragment;
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;}//此方法返回的片段在查看传呼机的每个位置
@覆盖
公共片段的getItem（INT位置）{ 如果（位置== 0）//如果位置是0，我们正在返回的第一个选项卡
{
返回this.mCurrent_forecast_fragment;
}
否则，如果（位置== 1）//因为我们有2个选项卡，如果现在的位置是0它必须是1，所以我们正在返回第二个标签
{
返回新Hourly_forecast_fragment（）;
}其他{
返回新Daily_forecast_fragment（）;
}}
}
I have a viewpager app that I am working on with 3 fragments. I am adding the fragments dynamically via the FragmentStatePagerAdapter like that:
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
CharSequence Titles[]; // This will Store the Titles of the Tabs which are Going to be passed when ViewPagerAdapter is created
int NumbOfTabs; // Store the number of tabs, this will also be passed when the ViewPagerAdapter is created
// Build a Constructor and assign the passed Values to appropriate values in the class
public ViewPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
super(fm);
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
//This method return the fragment for the every position in the View Pager
@Override
public Fragment getItem(int position) {
if(position == 0) // if the position is 0 we are returning the First tab
{
Current_forecast_fragment current_forecast_fragment = new Current_forecast_fragment();
return current_forecast_fragment;
}
else if (position == 1) // As we are having 2 tabs if the position is now 0 it must be 1 so we are returning second tab
{
return new Hourly_forecast_fragment();
}else {
return new Daily_forecast_fragment();
}
}
// This method return the titles for the Tabs in the Tab Strip
@Override
public CharSequence getPageTitle(int position) {
return Titles[position];
}
// This method return the Number of tabs for the tabs Strip
@Override
public int getCount() {
return NumbOfTabs;
}
}
How do I reference a fragment, lets say the current forecast one from my main activity? I tried something like that but I need the fragment id to reference it. Any suggestions?:
public class MainActivity extends AppCompatActivity {
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"Current","Hourly","Daily"};
int Numboftabs =3;
Current_forecast_fragment mCurrent_forecast_fragment;
public static final String TAG = MainActivity.class.getSimpleName();
public static final String LOCATION_KEY = "location_key";
public Forecast mForecast;
public static final String DAILY_FORECAST = "DAILY_FORECAST";
public static final String HOURLY_FORECAST = "HOURLY_FORECAST";
//default coordinates - Gotse Delchev, UK Lati:57.156866 ; Long:
private double latitude = 41.5667;
private double longitude = 23.7333;
private LocationManager locationManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//-----------MY CODE STARTS HERE-----------------
mCurrent_forecast_fragment = (Current_forecast_fragment) getSupportFragmentManager().findFragmentById(R.id.??????);
//Log.d("MainActivity",mCurrent_forecast_fragment.getTag() + "Georgi");
getLocation();
// Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
adapter = new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs);
// Assigning ViewPager View and setting the adapter
pager = (ViewPager) findViewById(R.id.pager);
pager.setAdapter(adapter);
// Assiging the Sliding Tab Layout View
tabs = (SlidingTabLayout) findViewById(R.id.tabs);
tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width
// Setting Custom Color for the Scroll bar indicator of the Tab View
tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
@Override
public int getIndicatorColor(int position) {
return getResources().getColor(R.color.tabsScrollColor);
}
});
// Setting the ViewPager For the SlidingTabsLayout
tabs.setViewPager(pager);
}
}
解决方案
After a lot of experimentation I came with a simple solution to my problem. Since I am adding the fragments dynamically (in the viewPagerAdapter) and not in XML I couldn't reference them weither by id or tag. My solution is to modify slightly the adapter so that it stores a reference of the fragment passed as a parameter. Then all of the methods of the fragment are accessible (if declired public) in the mainActivity:
MainActivity:
public class MainActivity extends AppCompatActivity {
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"Current","Hourly","Daily"};
int Numboftabs =3;
Current_forecast_fragment mCurrent_forecast_fragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//-----------MY CODE STARTS HERE-----------------
this.mCurrent_forecast_fragment = new Current_forecast_fragment();
// Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
adapter = new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs,mCurrent_forecast_fragment);
// Assigning ViewPager View and setting the adapter
pager = (ViewPager) findViewById(R.id.pager);
pager.setOffscreenPageLimit(3);
pager.setAdapter(adapter);
// Assiging the Sliding Tab Layout View
tabs = (SlidingTabLayout) findViewById(R.id.tabs);
tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width
// Setting Custom Color for the Scroll bar indicator of the Tab View
tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
@Override
public int getIndicatorColor(int position) {
return getResources().getColor(R.color.tabsScrollColor);
}
});
// Setting the ViewPager For the SlidingTabsLayout
tabs.setViewPager(pager);
}
My Code in ViewPagerAdapter:
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
private Current_forecast_fragment mCurrent_forecast_fragment;
CharSequence Titles[]; // This will Store the Titles of the Tabs which are Going to be passed when ViewPagerAdapter is created
int NumbOfTabs; // Store the number of tabs, this will also be passed when the ViewPagerAdapter is created
// Build a Constructor and assign the passed Values to appropriate values in the class
public ViewPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb,Current_forecast_fragment current_fragment) {
super(fm);
this.mCurrent_forecast_fragment = current_fragment;
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
//This method return the fragment for the every position in the View Pager
@Override
public Fragment getItem(int position) {
if(position == 0) // if the position is 0 we are returning the First tab
{
return this.mCurrent_forecast_fragment;
}
else if (position == 1) // As we are having 2 tabs if the position is now 0 it must be 1 so we are returning second tab
{
return new Hourly_forecast_fragment();
}else {
return new Daily_forecast_fragment();
}
}
}
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