在Android中实现onbacked

Question

我有Activity1将我带到了Activity2，这将我带到了片段。我想从碎片到返回活动2

public void onBackPressed() {
    Intent intent = new Intent(Intent.ACTION_MAIN);
    intent.addCategory(Intent.CATEGORY_HOME);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    startActivity(intent);
}

Answer 1

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() > 0) {
        getFragmentManager().popBackStack();
    }
    else
        super.onBackPressed();
}

Answer 2

添加activity的片段2

将其添加到背面

getSupportFragmentManager().beginTransaction()
                           .replace(R.id.frame_layout, new SampleFragment())
                           .addToBackStack(SampleFragment.class.getSimpleName())
                           .commit();

和onbackpressed检查片段是否存在于背串中并弹出

 @Override
public void onBackPressed() {
    if(getSupportFragmentManager().getBackStackEntryCount()>0){
        Fragment fragment=getSupportFragmentManager().findFragmentById(R.id.YOUR_FRAME_LAYOUT_ID);
        if(fragment!=null && fragment.getClass().getSimpleName().equalsIgnoreCase(SampleFragment.class.getSimpleName())){
            getSupportFragmentManager().popBackStackImmediate();
        }
    }else {
        super.onBackPressed();
    }
}

Answer 3

在片段上获取后压事件，并在那里调用

getactivity().getsupportfragmentmanager().popbackstack();

Answer 4

将片段交易添加到背面。