Android的onBackPressed()没有被调用? [英] Android onBackPressed() is not being called?

问题描述

在从AppCompatActivity扩展的MainActivity中，我想像这样重写onBackPressed方法:

in my MainActivity, which extends from AppCompatActivity, I want to override the onBackPressed method like so:

@Override
public void onBackPressed() {
    Log.d("MainActivity","onBackPressed");
    Toast.makeText(getApplicationContext(),"onBackPressed",Toast.LENGTH_SHORT).show();
}

，但不会调用onBackPressed.如果我不重写onBackPressed，该应用程序将关闭，当我按下后退按钮时，应用程序将关闭，如果我重写了它，则不会.

but onBackPressed does not get called. How ever if I do not override onBackPressed, the application closes, when I press the backbutton and if I do override it it doesn't.

其余的活动如下:

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private Drawer drawer;
private FloatingActionButton fab_test;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    fab_test = (FloatingActionButton) findViewById(R.id.fab_test);
    fab_test.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Toast.makeText(getApplicationContext(),"FAB Test pressed",Toast.LENGTH_SHORT).show();
        }
    });

    buildDrawer();

    getSupportFragmentManager().beginTransaction().add(R.id.fragmentContainer,page).commit();
}

@Override
public void onBackPressed() {
    Log.d("MainActivity","onBackPressed");
    Toast.makeText(getApplicationContext(),"onBackPressed",Toast.LENGTH_SHORT).show();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main_menu, menu);      
    return true;
}
}

我说的是硬件后退按钮(不是操作栏上的按钮)

I'm talking about the hardware-backbutton(not the actionbar one)

推荐答案

该问题已得到解答，但是我觉得需要清除本主题中的某些内容.大多数评论和答案指出使用super.onBackPressed()，这是导致方法onBackPressed()无法使用的原因.但这是不正确的，重要的是让其他初学者知道.方法onBackPressed()不需要使用super.onBackPressed().如果有人将super.onBackPressed()注释掉，onBackPressed()也可以使用.

This question is already answered, but I feel to clear something here in this topic. Most comments and answeres point out to use super.onBackPressed() and that this is the cause of the not working method onBackPressed(). But that is not correct and important to let other beginners know. The method onBackPressed() does not need to use super.onBackPressed() . onBackPressed()also works if somebody, for example, comment super.onBackPressed() out.

正如提问者所写，他不会使用super.onBackPressed()，因为它将关闭活动.因此，其无法正常工作的原因可以分为三个可能的原因:

As the questionier has written, he won´t use super.onBackPressed() because it will close the activity. So, the cause of this why it isn´t working, could be seperated into three possible causes:

1. 由于logcat控制台中的过滤器错误，日志无法正常工作
2. 由于错误的传递上下文，Toast不起作用
3. 供应商错误地实施了操作系统.

通常，吐司通过传递正确的上下文来起作用.对于发问者，只需传递this即可.

Usually, the toast works by passing the correct context. In the case of questioner, simply passing this .

@Override
public void onBackPressed() {
    Log.d("MainActivity","onBackPressed");
    Toast.makeText(this,"onBackPressed",Toast.LENGTH_SHORT).show();
}

对于日志，只需在logcat上设置正确的过滤器即可.

For the Log, simply set the correct filter on logcat.

我不在乎现在是否有人投降票，但对于其他初学者来说，必须明确指出，不得使用super.onBackPressed().

I don´t care if somebody give downvotes now, but it must be clear for other beginners, that super.onBackPressed() must not be used.

无论如何，使用onKeyDown()也是一种解决方案.

Anyway, the use of onKeyDown() also is a solution.

这篇关于Android的onBackPressed()没有被调用?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！