android - 应用程序在抽屉导航内的 fragment 内按下后退按钮时退出

Question

当我尝试从子 fragment 移动到父 fragment 时，我的应用程序退出(它不会崩溃)。这里 LandingActivity.java 是我调用 fragment ChannelGrid.java 的主要 Activity ，它调用 fragment GridMain.java。当我在 fragment 中按下移动设备的后退按钮 GridMain 应用程序退出而不是移至 ChannelGrid.java。我已将 addToBackStack("tag") 添加到 fragment 中，还尝试使用 onKey()..我也在不同的设备上测试了我的应用程序..我检查了找出具有相同问题的其他解决方案并进行了尝试，但没有任何效果..

抽屉导航-LandingActivity.java-ChaanelGrid.java(Fragment)-GridMain.java(Fragment)

登陆 Activity .java

   currentFragment = new ChaanelGrid();

                currentFragment.setArguments(args);
                frgManager = getFragmentManager();

                frgManager.beginTransaction().add(R.id.content_frame, currentFragment).addToBackStack("tag")
                        .commit();

ChanelGrid.java

Fragment currentFragment = new GridMain();



                    FragmentManager frgManager;
                    frgManager = getFragmentManager();
                    frgManager.beginTransaction().add(R.id.content_frame, currentFragment).addToBackStack("GridMain")
                            .commit()

GridMain.java(我也尝试过不使用 onKey() 方法但没有成功)

rootView.setOnKeyListener(new View.OnKeyListener() {


   @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_BACK)
            {
                Fragment currentFragment = new ChaanelGrid();


                FragmentManager frgManager;
                frgManager = getFragmentManager();
                frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
                        .commit();
                return true;
            }

详细的 logcat

   10-31 21:46:57.954  24452-24452/D/ActivityThread﹕ ACT-AM_ON_PAUSE_CALLED ActivityRecord{41eb8b98 token=android.os.BinderProxy@41bb9828 {xyz/xyz..activity.LandingActivity_}}
10-31 21:46:57.971  24452-24452/ D/ActivityThread﹕ ACT-PAUSE_ACTIVITY_FINISHING handled : 0 / android.os.BinderProxy@41bb9828
10-31 21:46:58.007  24452-24452/ V/InputMethodManager﹕ focusOut: android.widget.GridView@41f06f40 mServedView=android.widget.GridView@41f06f40 winFocus=false
10-31 21:46:58.297  24452-24452/ I/SurfaceTextureClient﹕ [0x5143bc58] frames:44, duration:1.002000, fps:43.883736
10-31 21:46:58.350  24452-24452/ D/OpenGLRenderer﹕ Flushing caches (mode 0)
10-31 21:46:58.432  24452-24452/ D/OpenGLRenderer﹕ Flushing caches (mode 0)
10-31 21:46:58.753  24452-24452/ D/OpenGLRenderer﹕ Flushing caches (mode 0)
10-31 21:46:58.754  24452-24452/ D/OpenGLRenderer﹕ Flushing caches (mode 0)
10-31 21:46:58.755  24452-24452/ D/OpenGLRenderer﹕ Flushing caches (mode 2)
10-31 21:46:58.879  24452-24452/ D/ActivityThread﹕ ACT-DESTROY_ACTIVITY handled : 1 / android.os.BinderProxy@41bb9828

我尝试在 LandingActivity.java 中添加以下内容

@Override

public void onBackPressed() {
    FragmentManager frgManager;
    frgManager = getFragmentManager();

    Fragment fragment = fragmentManager.findFragmentByTag("GridMain");
    if (fragment != null) {
        GridMain gridMain = (GridMain) fragment;
        if (!gridMain.onBackPressed()) {
            super.onBackPressed();
        }
    }
    else {
        super.onBackPressed();
    }
}

然后在 GridMain.java 中

   protected boolean onBackPressed() {
        FragmentManager frgManager;
        frgManager = getFragmentManager();
        frgManager.popBackStack();
        return true;
    }

使用 Log 我检查了 LandingActivity.java 的 onBackPressed() 被调用但仍然是相同的输出..

Answer 1

这就是我解决它的方法..当你在你的 fragment 中按下后退按钮时，如果你声明了你的 Activity 的 onBackPressed() 方法将被调用..因此处理抽屉导航中 fragment 的后退按钮可以是其中之一方式..

主要 Activity

     public static boolean isMainActivityShown ;
     public static boolean isFragment1Shown=false ;
     public static boolean isFragment2Shown=false ;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        isMainActivityShown=true  //inside onCreate method put isMainActivityShown true
        . 
        . 
        .
        {
        Fragment currentFragment = new Fragment1();
        isMainActivityShown=false;   //when moving to fragment1 
        isFragment1Shown=true;
        frgManager = getFragmentManager();
        frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
                                        .commit();
        }
        .
        .
        }
     @Override
        public void onBackPressed() {

            if(isMainActivityShown)
            {
                finish();
            }
            else if(isFragment1Shown)
            {
               //write the code to handle back button when you are in Fragment1
            }
           else if(isFragment2Shown)
            {  //When you are in Fragment 2 pressing back button will move to fragment1
                Fragment currentFragment = new Fragment1();
                isFragment2Shown=false;
                isFragment1Shown=true;

                FragmentManager frgManager;
                frgManager = getFragmentManager();
                frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
                        .commit();
            }

            }

fragment 1

Fragment currentFragment = new Fragment2();
MainActivity.isFragment1Shown=false;
MainActivity.isFragment2Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
                                    .commit();