如何获取activity的当前内容视图？

Question

我在主要 activity 上有一个内容视图说主要设置，当单击一个按钮时，它设置另一个内容视图说 setContentView(R.layout.sec_content)。我现在想要的是，当按下后退按钮时，如果当前视图是次要的，它应该设置主要内容，否则它应该关闭 activity。我怎么做？这是我的代码

public class Ch_1 extends AppCompatActivity {

Button men1, men2, men3;
TextView tv1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_ch_1);

    men1 = (Button)findViewById(R.id.men1);
    men1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            setContentView(R.layout.activity_read__view);
            TextView tv1 = (TextView)findViewById(R.id.read_view);
            tv1.setText("This is text in READ_VIEW activity");




        }
    });


}

}

Answer 1

public class MainActivity extends AppCompatActivity {

Boolean isClose = true;
Button btn;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn = (Button) findViewById(R.id.button);
}

public void onpressed(View view){
    isClose = false;
    setContentView(R.layout.second);
}

@Override
public void onBackPressed() {
    if (isClose){
        finish();
    } else {
        setContentView(R.layout.activity_main);
        isClose = true;
    }
}

}

如何获取activity的当前内容视图？

How to get current content view of activity?

android

onbackpressed

setcontentview