protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button b1 = (Button) findViewById(R.id.StartAnotherAty);         //这里的startAnotherAty是button的ID
    b1.setOnClickListener(new Button.OnClickListener() {          //button点击跳转
        public void onClick(View v) {                   
            Intent intent = new Intent();                //new一个Intent对象,并且指定要启动的class
            intent.setClass(MainActivity.this, AnotherAty.class);    //anotherAty是新建的activity
            startActivity(intent);                    //调用新的class
        }
    });
}
原文:http://www.cnblogs.com/bycainiao/p/5178829.html