Android - 在寻呼机中获取片段的上下文 _Android

得意犹堪夸世俗，诏黄新湿字如鸦。这篇文章主要讲述Android - 在寻呼机中获取片段的上下文相关的知识，希望能为你提供帮助。
我有一个使用寻呼机作为导航的android应用程序。对于选项卡，我有3个布局作为内容。其中一个片段是一个画廊，我想添加图像。为此，我必须设置一个ImageAdapter，但我需要知道如何访问片段的上下文。

final LayoutInflater factory = getLayoutInflater(); final View view = factory.inflate(R.layout.pictures, null); Gallery g = (Gallery) view.findViewById(R.id.gallery1); g.setAdapter(new ImageAdapter(view.getContext()));

我在onCreate方法中使用上面的代码从不是contentview的布局中获取库。我必须给ImageAdapter一个Context。但是我必须在那里设置什么背景？
编辑：这是我的完整代码：

package com.bw2801.uwelugemediathek; import java.util.Locale; import android.app.ActionBar; import android.app.FragmentTransaction; import android.content.Context; import android.database.DataSetObserver; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.util.Log; import android.view.LayoutInflater; import android.view.Menu; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageView; import android.widget.SpinnerAdapter; import android.widget.Toast; public class MainActivity extends FragmentActivity implements ActionBar.TabListener {SectionsPagerAdapter mSectionsPagerAdapter; ViewPager mViewPager; PicturesSectionFragment ps = new PicturesSectionFragment(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Set up the action bar. final ActionBar actionBar = getActionBar(); actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); // Create the adapter that will return a fragment for each of the three // primary sections of the app. mSectionsPagerAdapter = new SectionsPagerAdapter( getSupportFragmentManager()); // Set up the ViewPager with the sections adapter. mViewPager = (ViewPager) findViewById(R.id.pager); mViewPager.setAdapter(mSectionsPagerAdapter); // When swiping between different sections, select the corresponding // tab. We can also use ActionBar.Tab#select() to do this if we have // a reference to the Tab. mViewPager .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() { @Override public void onPageSelected(int position) { actionBar.setSelectedNavigationItem(position); } }); // For each of the sections in the app, add a tab to the action bar. for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) { // Create a tab with text corresponding to the page title defined by // the adapter. Also specify this Activity object, which implements // the TabListener interface, as the callback (listener) for when // this tab is selected. actionBar.addTab(actionBar.newTab() .setText(mSectionsPagerAdapter.getPageTitle(i)) .setTabListener(this)); }final LayoutInflater factory = getLayoutInflater(); final View view = factory.inflate(R.layout.pictures, null); Gallery g = (Gallery) view.findViewById(R.id.gallery1); g.setAdapter(new ImageAdapter(ps.getActivity())); }public class ImageAdapter extends BaseAdapter { private Context mContext; private Integer[] mImageIds = { R.drawable.image01, R.drawable.image02, R.drawable.image03, R.drawable.image04, R.drawable.image05, R.drawable.image06, R.drawable.image07, R.drawable.image08, }; public ImageAdapter(Context c) { mContext = c; }public int getCount() { return mImageIds.length; }public Object getItem(int position) { return position; }public long getItemId(int position) { return position; }public View getView(int position, View convertView, ViewGroup parent) { ImageView i = new ImageView(mContext); i.setImageResource(mImageIds[position]); i.setLayoutParams(new Gallery.LayoutParams(150, 100)); i.setScaleType(ImageView.ScaleType.FIT_XY); return i; } }@Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; }@Override public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { // When the given tab is selected, switch to the corresponding page in // the ViewPager. mViewPager.setCurrentItem(tab.getPosition()); }@Override public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { }@Override public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { }/** * A {@link FragmentPagerAdapter} that returns a fragment corresponding to * one of the sections/tabs/pages. */ public class SectionsPagerAdapter extends FragmentPagerAdapter {public SectionsPagerAdapter(FragmentManager fm) { super(fm); }@Override public Fragment getItem(int position) { switch(position) { case 0: return new DummySectionFragment(); case 1: return new SoundSectionFragment(); case 2: return ps; } return new DummySectionFragment(); }@Override public int getCount() { return 3; }@Override public CharSequence getPageTitle(int position) { switch (position) { case 0: return "Informationen"; case 1: return "Soundboard"; case 2: return "Galerie"; } return null; } }public static class DummySectionFragment extends Fragment {public DummySectionFragment() { }@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.info, container, false); } }public static class PicturesSectionFragment extends Fragment {public PicturesSectionFragment() { }@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.pictures, container, false); } }public static class SoundSectionFragment extends Fragment {public SoundSectionFragment() { }@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.sounds, container, false); } } }

答案片段没有自己的Context，它们使用父Activity。

要获取父活动上下文，请使用getActivity()
要使用应用程序上下文，请使用getActivity().getApplicationContext()

尽可能优先选择应用程序上下文。
更新：
当且仅当所述片段当前附加到活动时，片段的getActivity()返回一个Activity实例。
所以，

Fragment f = new MyFragment();

创建一个片段，但它尚未附加到一个活动。因此f.getActivity()返回null。
添加到活动后：

getFragmentManager().beginTransaction().add(f,"fragment").commit();

现在，getActivity()将返回一个Activity实例。
再次，如果我们从Activity中分离片段：

getFragmentManager().beginTransaction().detach(f).commit()

getActivity()将再次返回null值。
因此，我们不应该在getActivity()类之外使用Fragment，因为我们无法确定附加状态。因此，我建议你在其方法中使用getActivity()片段自己的类：onAttach()，onCreate()或onActivityCreated()。
另一答案你可以这样使用

g.setAdapter(new ImageAdapter(getActivity()));

另一答案获取我发现的片段上下文的最简单，最精确的方法是在调用onCreateView方法时直接从ViewGroup获取它，至少在这里你肯定不会为getActivity（）获取null

public class Animal extends Fragment {Context thiscontext; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {thiscontext = container.getContext();

另一答案

write under code in Your CoreApplication.javastep1) public class CoreApplication extends Application {private static CoreApplication instance; }step2) onCreate(){instance = this; }step3 ) add under method()

【Android - 在寻呼机中获取片段的上下文】public static CoreApplication getGlobalApplicationContext（）{

if (instance == null) { throw new IllegalStateException("this application does not inherit GlobalApplication"); " + "}return instance; }Step4) g.setAdapter(new ImageAdapter(getGlobalApplicationContext()));