android:如何在按钮点击时更改布局？

Question

我必须按照代码选择按钮点击时的布局.

View.OnClickListener handler = new View.OnClickListener(){
    public void onClick(View v) {

        switch (v.getId()) {

            case R.id.DownloadView: 
                // doStuff
                setContentView(R.layout.main);
                break;
            case R.id.AppView: 
                // doStuff
                setContentView(R.layout.app);
                break;
        }
    }
};

findViewById(R.id.DownloadView).setOnClickListener(handler);
findViewById(R.id.AppView).setOnClickListener(handler);

当我单击"AppView"按钮时,布局会发生变化,但是当我单击"DownloadView"按钮时,没有任何反应.

这个链接说我必须开始一项新的活动.

但我不知道如何使用意图开始新活动的代码,是否会添加新文件？

编辑:我有关于新活动的代码:

package com.example.engagiasync;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class AppView extends Activity implements OnClickListener{


    @Override
    public void onCreate(Bundle savedInstanceState){

        setContentView(R.layout.app);

        TextView tv = (TextView) this.findViewById(R.id.thetext);
        tv.setText("App View yo!?\n");
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub

    }
}

但它不起作用,强行关闭,logcat说:

Answer 1

  Button btnDownload = (Button) findViewById(R.id.DownloadView);
  Button btnApp = (Button) findViewById(R.id.AppView);

  btnDownload.setOnClickListener(handler);
  btnApp.setOnClickListener(handler);

  View.OnClickListener handler = new View.OnClickListener(){

  public void onClick(View v) {

    if(v==btnDownload){ 
            // doStuff
            Intent intentMain = new Intent(CurrentActivity.this , 
                                           SecondActivity.class);
            CurrentActivity.this.startActivity(intentMain);
            Log.i("Content "," Main layout ");
    }

    if(v==btnApp){ 
            // doStuff
            Intent intentApp = new Intent(CurrentActivity.this, 
                                          ThirdActivity.class);

            CurrentActivity.this.startActivity(intentApp);

            Log.i("Content "," App layout ");

    }
   }
  };

注意:然后您应该在清单.xml文件中声明所有活动,如下所示:

<activity android:name=".SecondActivity" ></activity>
<activity android:name=".ThirdActivity" ></activity>

编辑:更新这段代码:):

@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);// Add THIS LINE

    setContentView(R.layout.app);

    TextView tv = (TextView) this.findViewById(R.id.thetext);
    tv.setText("App View yo!?\n");
}

注意:检查此(断开链接)关于如何在活动之间切换的教程.

Answer 2

我会添加一个android:onClick布局,然后更改活动中的布局.

所以在布局中

<ImageView
(Other things like source etc.)
android:onClick="changelayout"
/>

然后在活动中添加以下内容:

public void changelayout(View view){
    setContentView(R.layout.second_layout);
}