Java 双击后按可退出应用程序
我有登录活动和三个片段，即加载程序、主页、，参加。现在，当我在主页中时，我希望我的应用程序通过点击backpressed退出。我已经成功实现了我的目标，但双重backpressed也应用于我不想要的参加片段中。在take Attention片段中，单击backpressed应该只转到上一个片段，但它不会发生 这是我的密码：- MainActivity.javaJava 双击后按可退出应用程序,java,android,android-fragments,Java,Android,Android Fragments,我有登录活动和三个片段，即加载程序、主页、，参加。现在，当我在主页中时，我希望我的应用程序通过点击backpressed退出。我已经成功实现了我的目标，但双重backpressed也应用于我不想要的参加片段中。在take Attention片段中，单击backpressed应该只转到上一个片段，但它不会发生 这是我的密码：- MainActivity.java @Override public void onBackPressed() { //for(int i=0;i
@Override
public void onBackPressed() {
//for(int i=0;i<getFragmentManager().getBackStackEntryCount();i++)
Home_Screen home_screen = (Home_Screen) getFragmentManager().findFragmentByTag
("Home_Screen_Teacher");
if (home_screen != null && home_screen.isVisible()) {
DrawerLayout navigation_drawer = home_screen.getView().findViewById(R.id.drawer_layout);
if (navigation_drawer.isDrawerOpen(GravityCompat.START)) {
navigation_drawer.closeDrawer(Gravity.LEFT);
}
else {
if (backpressedTime + 2000 > System.currentTimeMillis()) {
this.finish();
System.exit(0);
return;
}
else {
second=(int)(backpressedTime/1000);
Snackbar.make(findViewById(R.id.home_screen_teacher),"Detach",Snackbar.LENGTH_LONG).show();
}
backpressedTime = System.currentTimeMillis();
//super.onBackPressed();
}
}
else{
super.onBackPressed();
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View loadder_fragment=inflater.inflate(R.layout.fragment_loader_fragment, container, false);
Loader=(AVLoadingIndicatorView)loadder_fragment.findViewById(R.id.loder_login);
handler=new Handler();
runnable=new Runnable() {
@Override
public void run() {
Loader.setVisibility(View.INVISIBLE);
timer.cancel();
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator
.slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen();
fragmentTransaction.replace(R.id.Home_screen_fragment_3,home_screen,
"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
};
timer=new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
handler.post(runnable);
}
}, 5000,5000);
return loadder_fragment;
}
navigation_drawer=(DrawerLayout)Home_screen.findViewById(R.id.drawer_layout);
navigationView=(NavigationView)Home_screen.findViewById(R.id.Navigation_view_for_teacher);
home_screen_take_attendance_button=(Button)Home_screen.findViewById(R.id
.home_screen_take_attendance_button);
home_screen_take_attendance_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
getActivity().getFragmentManager().beginTransaction().replace(R.id
.fragment_take_attendance,new Take_attendance(),"take_attendence")
.addToBackStack(null).commit();
}
});
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator .slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen(); fragmentTransaction.replace(R.id.Home_screen_fragment1,home_screen,"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
//Some code
@Override
public void onBackPressed() {
//for(int i=0;i<getFragmentManager().getBackStackEntryCount();i++)
Home_Screen home_screen = (Home_Screen) getFragmentManager().findFragmentByTag
("Home_Screen_Teacher");
if (home_screen != null && home_screen.isVisible()) {
DrawerLayout navigation_drawer = home_screen.getView().findViewById(R.id.drawer_layout);
if (navigation_drawer.isDrawerOpen(GravityCompat.START)) {
navigation_drawer.closeDrawer(Gravity.LEFT);
}
else {
if (backpressedTime + 2000 > System.currentTimeMillis()) {
this.finish();
System.exit(0);
return;
}
else {
second=(int)(backpressedTime/1000);
Snackbar.make(findViewById(R.id.home_screen_teacher),"Detach",Snackbar.LENGTH_LONG).show();
}
backpressedTime = System.currentTimeMillis();
//super.onBackPressed();
}
}
else{
super.onBackPressed();
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View loadder_fragment=inflater.inflate(R.layout.fragment_loader_fragment, container, false);
Loader=(AVLoadingIndicatorView)loadder_fragment.findViewById(R.id.loder_login);
handler=new Handler();
runnable=new Runnable() {
@Override
public void run() {
Loader.setVisibility(View.INVISIBLE);
timer.cancel();
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator
.slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen();
fragmentTransaction.replace(R.id.Home_screen_fragment_3,home_screen,
"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
};
timer=new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
handler.post(runnable);
}
}, 5000,5000);
return loadder_fragment;
}
navigation_drawer=(DrawerLayout)Home_screen.findViewById(R.id.drawer_layout);
navigationView=(NavigationView)Home_screen.findViewById(R.id.Navigation_view_for_teacher);
home_screen_take_attendance_button=(Button)Home_screen.findViewById(R.id
.home_screen_take_attendance_button);
home_screen_take_attendance_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
getActivity().getFragmentManager().beginTransaction().replace(R.id
.fragment_take_attendance,new Take_attendance(),"take_attendence")
.addToBackStack(null).commit();
}
});
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator .slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen(); fragmentTransaction.replace(R.id.Home_screen_fragment1,home_screen,"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
//Some code
@Override
public void onBackPressed() {
//for(int i=0;i<getFragmentManager().getBackStackEntryCount();i++)
Home_Screen home_screen = (Home_Screen) getFragmentManager().findFragmentByTag
("Home_Screen_Teacher");
if (home_screen != null && home_screen.isVisible()) {
DrawerLayout navigation_drawer = home_screen.getView().findViewById(R.id.drawer_layout);
if (navigation_drawer.isDrawerOpen(GravityCompat.START)) {
navigation_drawer.closeDrawer(Gravity.LEFT);
}
else {
if (backpressedTime + 2000 > System.currentTimeMillis()) {
this.finish();
System.exit(0);
return;
}
else {
second=(int)(backpressedTime/1000);
Snackbar.make(findViewById(R.id.home_screen_teacher),"Detach",Snackbar.LENGTH_LONG).show();
}
backpressedTime = System.currentTimeMillis();
//super.onBackPressed();
}
}
else{
super.onBackPressed();
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View loadder_fragment=inflater.inflate(R.layout.fragment_loader_fragment, container, false);
Loader=(AVLoadingIndicatorView)loadder_fragment.findViewById(R.id.loder_login);
handler=new Handler();
runnable=new Runnable() {
@Override
public void run() {
Loader.setVisibility(View.INVISIBLE);
timer.cancel();
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator
.slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen();
fragmentTransaction.replace(R.id.Home_screen_fragment_3,home_screen,
"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
};
timer=new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
handler.post(runnable);
}
}, 5000,5000);
return loadder_fragment;
}
navigation_drawer=(DrawerLayout)Home_screen.findViewById(R.id.drawer_layout);
navigationView=(NavigationView)Home_screen.findViewById(R.id.Navigation_view_for_teacher);
home_screen_take_attendance_button=(Button)Home_screen.findViewById(R.id
.home_screen_take_attendance_button);
home_screen_take_attendance_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
getActivity().getFragmentManager().beginTransaction().replace(R.id
.fragment_take_attendance,new Take_attendance(),"take_attendence")
.addToBackStack(null).commit();
}
});
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
fragmentManager=getFragmentManager();
fragmentTransaction=fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.animator.slide_in_left,R.animator .slide_out_left,R.animator.slide_in_right,R.animator.slide_out_right);
Home_Screen home_screen=new Home_Screen(); fragmentTransaction.replace(R.id.Home_screen_fragment1,home_screen,"Home_Screen_Teacher");
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
//Some code
请帮助。我在过去两天一直遇到这个问题。我已经实现了我的目标，但退出应用程序的双反压也在take Attention片段中工作，我不希望它出现。在应用
onBackPressed（）@Override
public void onBackPressed() {
int backStackCount = getSupportFragmentManager().getBackStackEntryCount();
if (backStackCount > 0) {
// returns to previous fragment
getSupportFragmentManager().popBackStack();
} else {
// apply your "double press" logic
super.onBackPressed();
}
}
在每个片段中，我需要添加“addBackStack（null）”创建
片段事务时，您需要应用，但我需要应用于特定片段。因此，我们如何获取该片段。我需要应用于主屏幕片段。如何获取主屏幕片段的对象，以便在活动中实现。检查当前显示的片段是否为您的主屏幕片段。请参阅：