写下如下代码即可

import android.content.ComponentName; //引入

Intent mIntent = new Intent("android.intent.action.MAIN");
ComponentName comp = new ComponentName("你要启动app的包命，如：com.android.app", "你要启动app的首页，如：com.android.app.MainAcrivity");
mIntent.setComponent(comp);
mIntent.addCategory("android.intent.category.LAUNCHER"); 
startActivity(mIntent);//启动
finish();//关闭app