Android 从Activity返回数据

Main.java

public class Main extends Activity {

    private Button button;
    private EditText input1, input2, result;
    private final static int REQUEST_CODE=1;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        input1 = (EditText)this.findViewById(R.id.input1);
        input2 = (EditText)this.findViewById(R.id.input2);


        button = (Button)this.findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                String input1str = input1.getText().toString();
                String input2str = input2.getText().toString();
                int a = Integer.parseInt(input1str);
                int b = Integer.parseInt(input2str);

                Intent intent = new Intent(Main.this, OtherActivity.class);
                intent.putExtra("a",a);
                intent.putExtra("b",b);
                startActivityForResult(intent, REQUEST_CODE);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode==OtherActivity.RESULT_CODE){
            if(requestCode==REQUEST_CODE){
                int return_int = data.getIntExtra("result",0);
                result = (EditText)this.findViewById(R.id.result);
                result.setText(return_int);
            }
        }
    }
｝

OtherActivity.java

public class OtherActivity extends Activity{

    private TextView label;
    private EditText input;
    private Button button;
    public final static int RESULT_CODE=2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.other);

        label = (TextView)this.findViewById(R.id.label);
        input = (EditText)this.findViewById(R.id.input);
        button =(Button)this.findViewById(R.id.button);

        Intent intent = getIntent();
        int a = intent.getIntExtra("a", 0);
        int b = intent.getIntExtra("b", 0);
        label = (TextView)this.findViewById(R.id.label);
        label.setText(a +  " + " + b + " = ?");

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int input_int =  Integer.parseInt(input.getText().toString());

                Intent intent = new Intent();
                intent.putExtra("result", input_int);
                //通过Intent对象返回结果，使setResult
                setResult(RESULT_CODE,intent);
                //结束当前的Activity生命周期
                finish();
            }
        });

    }
}