Android 在一个应用中如何启动另外一个已安装的应用

在自己的apk中如何来启动另外的一个apk

package com.cn;import android.app.Activity;import android.content.ComponentName;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.widget.Button;public class MainActivity extends Activity {private Button myBut;private String tongfang = "com.android.tongfang";@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);myBut = (Button) findViewById(R.id.my_but);myBut.setOnClickListener(new Button.OnClickListener() {public void onClick(View v) {//Intent intent = new Intent(tongfang);//startActivity(intent);Intent mIntent = new Intent( ); ComponentName comp = new ComponentName(tongfang, "com.android.tongfang.MainActivity");     mIntent.setComponent(comp); mIntent.setAction("android.intent.action.VIEW"); startActivity(mIntent);}});}}

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