Intent intent = new Intent(Main.this, SecondActivity.class);
startActivity(intent);

startActivityForResult(Intent intent, Int requestCode)

public class MainActivity extends Activity {
  /** Called when the activity is first created. */
   @Override
    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      //给按钮添加绑定的事件
      Button myButton = (Button)findViewById(R.id.myButton);
      myButton.setText("我的第一个Button");
      myButton.setOnClickListener(new OnClick());
    }
   @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    System.out.println(requestCode);
    System.out.println(resultCode);
  }
   public class OnClick implements OnClickListener{
      @Override
      public void onClick(View v) {
        //生成一个Intent对象
        Intent intent = new Intent();
        intent.putExtra("testIntent", "testExtra");
        intent.setClass(MainActivity.this,SecondActivity.class);
        //直接启动一个Activity
//       startActivity(intent);
        //启动一个有返回值的Activity
        startActivityForResult(intent, 2);
      }
    }
}