[英]App exits on presing back button inside fragments within navigation drawer
當我嘗試從子片段移動到父片段時,我的應用程序退出(它不會崩潰).Hhere LandingActivity.java是我調用片段ChannelGrid.java的主要活動,它調用片段GridMain.java。當我按下后退按鈕時片段中的移動設備GridMain應用程序退出而不是移動到ChannelGrid.java.I已經添加了addToBackStack(“tag”)到片段並嘗試使用onKey()..我在不同設備上測試了我的應用程序..我檢查了其他解決方案有同樣的問題並嘗試過但沒有任何作用..
Navigation Drawer-LandingActivity.java-ChaanelGrid.java(Fragment)-GridMain.java(Fragment)
LandingActivity.java
currentFragment = new ChaanelGrid();
currentFragment.setArguments(args);
frgManager = getFragmentManager();
frgManager.beginTransaction().add(R.id.content_frame, currentFragment).addToBackStack("tag")
.commit();
ChaanelGrid.java
Fragment currentFragment = new GridMain();
FragmentManager frgManager;
frgManager = getFragmentManager();
frgManager.beginTransaction().add(R.id.content_frame, currentFragment).addToBackStack("GridMain")
.commit()
GridMain.java(我試過沒有onKey()方法但也沒用)
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;
}
logcat詳細
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
我嘗試在LandingActivity.java中添加以下內容
@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();
}
}
並在GridMain.java中跟隨
protected boolean onBackPressed() {
FragmentManager frgManager;
frgManager = getFragmentManager();
frgManager.popBackStack();
return true;
}
使用Log我檢查了LandingActivity.java的onBackPressed(),但仍然是相同的輸出..
這就是我解決它的方法..當你按下片段里面的后退按鈕onBackPressed()時你的活動方法會被調用,如果你已經聲明了那么......導航抽屜里的片段處理后退按鈕就可以這樣了。
MainActvity
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();
}
}
片段1
Fragment currentFragment = new Fragment2();
MainActivity.isFragment1Shown=false;
MainActivity.isFragment2Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
這就是我通常處理后退按鈕的方式:
// "State Machine" variables: to indicate which is the active Fragment.
private static boolean isHelpShown = false;
protected static boolean isInfoShown = false;
protected static boolean isMainShown = false;
private static boolean isViewShown = false;
// Used to switch between Fragments.
private static enum Fragments
{
MAIN,
VIEW,
HELP,
INFO
}
@Override
public final void onBackPressed()
{
if (isMainShown)
{
// We're in the MAIN Fragment.
finish();
}
else
{
// We're somewhere else, reload the MAIN Fragment.
showFragment(Fragments.MAIN);
}
}
private final void showFragment(final Fragments FragmentType)
{
isViewShown = false;
isHelpShown = false;
isInfoShown = false;
isMainShown = false;
final FragmentTransaction ft =
getSupportFragmentManager().beginTransaction();
/*
Replace whatever is in the fragment_container view with this
fragment, and add the transaction to the back stack so the user can
navigate back.
*/
switch(FragmentType)
{
case HELP:
{
ft.replace(R.id.frgMaster, new FRG_Help());
isHelpShown = true;
break;
}
case INFO:
{
ft.replace(R.id.frgMaster, new FRG_Info());
isInfoShown = true;
break;
}
case VIEW:
{
ft.replace(R.id.frgMaster, new FRG_View());
isViewShown = true;
break;
}
case MAIN:
{
ft.replace(R.id.frgMaster, new FRG_Main());
isMainShown = true;
break;
}
}
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
// Finalize the transaction...
ft.commit();
getSupportFragmentManager().executePendingTransactions();
}
正如你所看到的,根據我的需要,我只處理MAIN片段(我退出)或者當我們不在時(我回到MAIN片段:另一個Back press並退出)。
您可以在onBackPressed方法中添加更多檢查,以檢查您是否在另一個片段中並相應地加載另一個片段。
我建議使用TAG替換片段來產生相同的結果。
簡單示例如下所示
使用TAG將片段B添加到活動中
fragmentTransaction.replace(R.id.main_fragment_container,new FragmentB(),“TAG_B”);
片段A - >片段B [onBackPressed] - >片段A覆蓋Activity文件中的onBackPressed(),其中,
//檢查片段B,你正在查看片段B.
if(getSupportFragmentManager()。findFragmentByTag(“TAG_B”)!= null){fragmentTransaction.replace(R.id.main_fragment_container,new FragmentA(),“TAG_A”);
}
我嘗試了這里建議的所有解決方案,但沒有一個適合我。 這就是我最終通過修改最高投票答案來解決它的方法:
在托管片段的活動中,聲明FragmentManager
private FragmentManager fragmentManager;
在onCreateMethod中初始化它:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManager = getFragmentManager();
...
最后,在你的onBackPressed方法中執行以下操作:
public void onBackPressed() {
if(fragmentManager.getBackStackEntryCount() != 0) {
fragmentManager.popBackStack();
if (IS_MAIN_SHOWN) {
finish();
} else {
displayView(0); //this is the method that changes the fragments, takes an int argument for the position of the fragment.
}
} else {
super.onBackPressed();
}
}
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