直接上程式碼

第一個Activty：

public class MainActivity extends Activity {
    // 請求碼，必須是唯一值
    private static final int TO_SECOND_ACTIVITY = 1;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button gotoSecond = (Button) findViewById(R.id.button_1);
        gotoSecond.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                String data = "進入SecondActivity";
                intent.putExtra("extra_data", data);
                startActivityForResult(intent, TO_SECOND_ACTIVITY);
            }
        });
    }

    // 上面使用startActivityForResult()方法來啟動SecondActivity
    // 則SecondActivity銷燬後會回撥onActivityResult()方法
    // 在這裡得到返回的資料
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == TO_SECOND_ACTIVITY) {
            switch (resultCode) {
            case RESULT_OK:
                String returnData = data.getStringExtra("data_return");
                Toast.makeText(this, returnData, Toast.LENGTH_LONG).show();
                break;
            default:
            }
        }
    }    
}
 

public class SecondActivity extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.second_activity);
        
        // 獲取傳入的資料並顯示
        Intent intent = getIntent();
        String data = intent.getStringExtra("extra_data");
        Toast.makeText(this, data, Toast.LENGTH_LONG).show();
        
        // 點選按鈕返回上一個Activity
        Button finishThis = (Button) findViewById(R.id.button_finish_2);
        finishThis.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                returnDataAndClose();
            }
        });
    }
    
    // 返回資料並關閉當前活動
    private void returnDataAndClose(){
        Intent intent = new Intent();
        intent.putExtra("data_return", "學習安卓");
        setResult(RESULT_OK, intent);
        finish();
    }

    // 按下手機上的返回鍵時呼叫此活動
    @Override
    public void onBackPressed() {
        returnDataAndClose();
    }
    
    
}