onActivityResult()的用法

在一个主界面(主Activity)上能连接往许多不同子功能模块(子Activity上去)，当子模块的事情做完之后就回到主界面，或许还同时返回一些子模块完成的数据交给主Activity处理。这样的数据交流就要用到回调函数onActivityResult()。

public class MainActivity extends Activity {
    public final int REQUESTCODE_FROM_MAIN_TO_OTHER = 1;
    public final int REQUESTCODE_FROM_MAIN_TO_PEPELU = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn_start_other = (Button) findViewById(R.id.btn_start_other);
        btn_start_other.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setClass(MainActivity.this, OtherActivity.class);
                // 如果REQUESTCODE_MAIN> =0,当Activity结束时requestCode将归还在onActivityResult()中。
　　             //以便确定返回的数据是从哪个Activity中返回
                startActivityForResult(intent, REQUESTCODE_FROM_MAIN_TO_OTHER);
            }
        });
        Button btn_start_pepelu = (Button) findViewById(R.id.btn_start_pepelu);
        btn_start_pepelu.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setClass(MainActivity.this, PepeluActivity.class);
                startActivityForResult(intent, REQUESTCODE_FROM_MAIN_TO_PEPELU);
            }
        });

    }

    /**
     * requestCode和startActivityForResult中的requestCode相对应
     * resultCode和Intent是由子Activity通过其setResult()方法返回
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
        case REQUESTCODE_FROM_MAIN_TO_OTHER:
            if (resultCode == Activity.RESULT_OK) {
                Toast.makeText(this, data.getStringExtra("name"), Toast.LENGTH_LONG).show();
                Log.i("onactivityresultdemo", data.getStringExtra("name"));
            } else {
                Log.i("onactivityresultdemo", "i blabalabal");
            }
            break;
        case REQUESTCODE_FROM_MAIN_TO_PEPELU:
            if (resultCode == Activity.RESULT_CANCELED) {
                Toast.makeText(this, data.getStringExtra("name"), Toast.LENGTH_LONG).show();
                Log.i("onactivityresultdemo", data.getStringExtra("name"));
            } else {
                Log.i("onactivityresultdemo", "i blabalabal");
            }
            break;
        default:
            break;
        }
    }
}

 在OtherActivity中设置返回码和返回数据:

public class OtherActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_other);

        Button btn = (Button) findViewById(R.id.btn_other);
        btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.putExtra("name", "cc");
                // 设置返回码和返回携带的数据
                setResult(Activity.RESULT_OK, intent);

            }
        });
    }

}

在PepeluActivity中设置返回码和返回数据:

public class PepeluActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pepelu);
        Button btn_pepelu=(Button) findViewById(R.id.btn_pepelu);
        btn_pepelu.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                Intent intent=new Intent();
                intent.putExtra("name", "pepelu");
                setResult(Activity.RESULT_CANCELED,intent);
            }
        });
    }
}