從Activity1帶引數跳轉到Activity2這個經常用到，比較熟悉，但如何從Activity2將資料返回給Activity1呢？這個其實也不麻煩，動手敲一下就知道了。

Activity1程式碼：

public class MainActivity extends ActionBarActivity {

    private Button button;

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

        button = (Button) findViewById(R.id.main_btn);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,SecondActivity.class);
                intent.putExtra("data","data");
                startActivityForResult(intent, 99);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == 99){
            if(resultCode == 88){
                Bundle bundle = data.getExtras();
                String back = bundle.getString("back");
                Toast.makeText(MainActivity.this,back,Toast.LENGTH_SHORT).show();
            }
        }
    }
}
 

這次我們是需要返回值，所以呼叫startActivityForResult(intent, 99);第二個引數為requestcode。在下面的onActivityResult(int requestCode, int resultCode, Intent data) 方法中

，首先判斷requestcode，再判斷resultCode,resultCode是在第二個Activity中，我們呼叫setResult()方法中的一個引數，兩個必須一樣。

下面是第二個Activity的程式碼：

public class SecondActivity extends Activity {

    private static final String TAG = "zh";
    private Button btn2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.item);

        String str = getIntent().getStringExtra("data");
        Log.i(TAG,str);
        btn2 = (Button) findViewById(R.id.second_btn);

        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.putExtra("back","我是返回的資料");
                setResult(88,intent);
                finish();
            }
        });

    }