将活动保留在堆栈中，但仅返回到主

Question

我有九项活动。例如，活动“A”是主要活动。用户从 NavigationDrawer 打开活动“B”、“С”、“D”并在“D”中单击“返回”按钮。在这种情况下，需要返回到 Activity “A”，而不是通过整个最近打开的 Activity 堆栈。

这段代码可以满足我的需要：

@Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        Handler mHandler = new Handler();
        drawerLayout.closeDrawers();
        switch (item.getItemId()) {
            case R.id.A:
                if (item.isChecked()) {
                    break;
                } else {
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            intent = new Intent(activity, A.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                            activity.startActivity(intent);
                        }
                    }, 250);
                }
                break;
            case R.id.B:
                if (item.isChecked()) {
                    break;
                } else {
                    if (activity instanceof A) {
                        userFlavorsMap.clear();
                        if (flavorContainer.getChildCount() > 0){
                            flavorContainer.removeAllViews();
                        }
                    }
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            intent = new Intent(activity, B.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                            activity.startActivity(intent);
                        }
                    }, 250);
                }
                break;
            case R.id.C:
                if (item.isChecked()) {
                    break;
                } else {
                    if (activity instanceof A) {
                        userFlavorsMap.clear();
                        if (flavorContainer.getChildCount() > 0){
                            flavorContainer.removeAllViews();
                        }
                    }
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            intent = new Intent(activity, C.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                            activity.startActivity(intent);
                        }
                    }, 250);
                }
                break;
            case R.id.D:
                if (item.isChecked()) {
                    break;
                } else {
                    if (activity instanceof A) {
                        userFlavorsMap.clear();
                        if (flavorContainer.getChildCount() > 0){
                            flavorContainer.removeAllViews();
                        }
                    }
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            intent = new Intent(activity, D.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                            activity.startActivity(intent);
                        }
                    }, 250);
                }
                break;
            case R.id.E:
                if (item.isChecked()) {
                    break;
                } else {
                    if (activity instanceof A) {
                        userFlavorsMap.clear();
                        if (flavorContainer.getChildCount() > 0){
                            flavorContainer.removeAllViews();
                        }
                    }
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            intent = new Intent(activity, E.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                            activity.startActivity(intent);
                        }
                    }, 250);
                }
                break;
            case R.id.F:
                File usersCounter = new File("data/data/com.com.com/shared_prefs/file.xml");
                if (usersCounter.exists()) {
                    if (item.isChecked()) {
                        break;
                    } else {
                        if (activity instanceof A) {
                            userFlavorsMap.clear();
                            if (flavorContainer.getChildCount() > 0){
                                flavorContainer.removeAllViews();
                            }
                        }
                        mHandler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                intent = new Intent(activity, F.class);
                                intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                                activity.startActivity(intent);
                            }
                        }, 250);
                    }
                    break;
                } else {
                    if (item.isChecked()) {
                        break;
                    } else {
                        if (activity instanceof A) {
                            userFlavorsMap.clear();
                            if (flavorContainer.getChildCount() > 0){
                                flavorContainer.removeAllViews();
                            }
                        }
                        mHandler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                intent = new Intent(activity, G.class);
                                intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                                activity.startActivity(intent);
                            }
                        }, 250);
                    }
                    break;
                }
        }
        return false;
    }

但是，如果用户切换到Activity，例如“C”并折叠应用程序，那么返回应用程序后会打开“A”。如何完成代码，以便当我返回应用程序时，它会打开最后打开的 Activity，但所有最近的 Activity 都不会在堆栈中？

在manifect android:launchMode="singleTop"

Answer 1

在除 MainActivity 之外的每个活动中尝试此操作

 @Override
    public void onBackPressed() {
        super.onBackPressed();
        Intent mainIntent = new Intent(YourCurrentActivityName.this,MainActivity.class);
        startActivity(mainIntent);
        finish();
    }