onBackPressed with Fragments Android

Question

我试图在具有3个片段的活动上实现on式倾斜。我的问题是，我在一段时间方法后实现了"再次按要退出"，但是当单击两次后按钮时，它返回到上一个片段而不是退出。当调用该片段时，就会发生这种情况（即，如果我打开游戏并立即退出，它像魅力一样起作用）。我对主活动的on式压制方法看起来像这样;

@Override
public void onBackPressed() {
    if(getSupportFragmentManager().getBackStackEntryCount()!=0) {
        getSupportFragmentManager().popBackStack();
    }
    this.findViewById(R.id.linearLayout1).setVisibility(View.VISIBLE);
    if(mBackPressed + TIME_INTERVAL > System.currentTimeMillis() && getSupportFragmentManager().getBackStackEntryCount()==0){
        super.onBackPressed();
        System.exit(0);
        this.finish();
    }
    else { Toast.makeText(getBaseContext(), "Press back once more to exit", Toast.LENGTH_SHORT).show(); }
    mBackPressed = System.currentTimeMillis();
}

我基本上想检查用户是否处于MainActivity布局中，以便我可以使用PopBackStack逃避。任何解决方案都将不胜感激，如果这还不够，我可以提供更多信息。

谢谢bektaş

Answer 1

如果您真的想退出，请完全忽略背面堆栈。使用此代码。

@Override
public void onBackPressed() {
    this.findViewById(R.id.linearLayout1).setVisibility(View.VISIBLE);
    if(mBackPressed + TIME_INTERVAL > System.currentTimeMillis()){
        this.finish();
        return;
    }
    else { 
       Toast.makeText(getBaseContext(), "Press back once more to exit", Toast.LENGTH_SHORT).show(); 
    }
    mBackPressed = System.currentTimeMillis();
}

Answer 2

我认为您可能会发现此链接有用http://developer.android.com/training/implementing-navigation/temporal.html

它说您可以使用此paturn

将引用添加到堆栈中

// Works with either the framework FragmentManager or the
// support package FragmentManager (getSupportFragmentManager).
getSupportFragmentManager().beginTransaction()
                           .add(detailFragment, "detail")
                       // Add this transaction to the back stack
                       .addToBackStack()
                       .commit();

Answer 3

@Override
public void onBackPressed() {
    int count = getSupportFragmentManager().getBackStackEntryCount();
    if (count == 0) {
        getSupportFragmentManager().popBackStack(getSupportFragmentManager().getBackStackEntryCount(), getSupportFragmentManager().POP_BACK_STACK_INCLUSIVE);
        android.app.AlertDialog.Builder builder = new android.app.AlertDialog.Builder(context);
        builder.setCancelable(false);
        builder.setMessage("Are you sure you want to exit?")
                .setNegativeButton(android.R.string.no, null)
                .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface arg0, int arg1) {
                        (Main Activity Name).super.onBackPressed();
                    }
                }).create().show();
    } else {
        super.onBackPressed();

    }
}