后退按钮不起作用

Question

I have an application with two activities. In the first activity it is possible to start the second by clicking a button.

@Override
public void onClick(View v) {
    Intent intent = new Intent(firstActivity, SecondAcitivity.class);
    startActivity(intent);
}

Bizarrely, clicking the back button in the second activity doesn't bring me back. I thought such basic behavior is already implemented so that I don't have to do anything about it. Actually in other apps I wrote there never has arisen such a problem.

Of course in the class of the first activity I have

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
    firstActivity = this;
    ...
}

Answer 1

Have you done something to intercept the key event?

For example:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK){
    return true;
}
return super.onKeyDown(keyCode, event);
}

or

@Override
public void onBackPressed() {
//not invoke the super.onBackPressed();
}