当前App跳转其他App指定的Activity

//1.你要跳转app的包名，你跳转的清单文件里的package名
//2.你要跳转app指定的Activity名
ComponentName comp = new ComponentName("com.example.demo","com.example.demo2.MainActivity");

还有

//

Intent it=new Intent(); 
it.setComponent(comp);
this.startActivity(it);

当一个App service里跳转其他App Activity时(我是在写悬浮框里的service遇到的)

ComponentName comp = new ComponentName("com.example.demo","com.example.demo.MainActivity");
Intent it = new Intent();
it.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);//需要加这个不然会报错
it.setComponent(comp);
startActivity(it);