片段getView在掛起後爲null

爲了關注這個問題，我結束了以下測試應用程序，其中包含一個活動和兩個連接到FragmentStatePagerAdapter/ViewPager的片段。我也每秒都有Runnable和Handler打印getView（）（在生產版本中，它用於在片段的TextView中顯示時間）。片段getView在掛起後爲null

當我啓動應用程序，getView（）表示，也許幾個空（我想，由於片段生命週期），然後我得到一些非空值這是確定...

但是，如果我暫停和喚醒我設備LogCat始終顯示空值。

public class MainActivity extends SherlockFragmentActivity { 

    private SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); 
    private Fragment myFragment1 = new MyFragment1(); 
    private Fragment myFragment2 = new MyFragment2(); 

    private Handler handler = new Handler(); 
    private Runnable timer; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     ViewPager viewPager = (ViewPager) findViewById(R.id.pager); 
     viewPager.setAdapter(sectionsPagerAdapter); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 

     timer = new Runnable() { 
      public void run() { 
       System.out.println(myFragment1.getView()); // HERE getView gives null 
       handler.postDelayed(this, 1000); // refreshing every 1 sec 
      } 
     }; 

     handler.removeCallbacks(timer); 
     handler.postDelayed(timer, 0); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 

     handler.removeCallbacks(timer); 
    } 

    public class SectionsPagerAdapter extends FragmentStatePagerAdapter { 

     public SectionsPagerAdapter(FragmentManager fm) { 
      super(fm); 
     } 

     @Override 
     public Fragment getItem(int position) { 
      Fragment fragment; 

      if (position == 0) { 
       fragment = myFragment1; 
      } else { 
       fragment = myFragment2; 
      } 

      return fragment; 
     } 

     @Override 
     public int getCount() { 
      return 2; 
     } 

     @Override 
     public CharSequence getPageTitle(int position) { 
      switch (position) { 
      case 0: 
       return "Fragment 1"; 
      case 1: 
       return "Fragment 2"; 
      } 
      return null; 
     } 

    } 
}

我的片段

public class MyFragment1 extends SherlockFragment { 

    private TextView textView2; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     return inflater.inflate(R.layout.fragment_layout, container, false); 
    } 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 

     ((TextView) getView().findViewById(R.id.textView1)).setText("Fragment 1"); 

     textView2 = (TextView) this.getView().findViewById(R.id.textView2); 
    } 

    public void updateTextView2(String text) { 
     textView2.setText(text); 
    }

來源

2013-01-17 krisk

好吧，我只是解決了我的問題，通過添加：

if (myFragment1.getView() == null) { 
    viewPager.setAdapter(sectionsPagerAdapter); 
}

我不滿意這個解決方案，但它的工作原理...

來源

2013-01-18 18:14:53 krisk

片段getView在掛起後爲null

回答

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