Activity 之间的回调得不到结果

在开发当中我们有时候需要ActivityA 的值或者变量传输到 ActivityB在B 界面得到A–>B 的内容值，并返回处理结果！这时候我们就可以使用startActivityForResult 进行开启一个新的界面，使用 setResult 进行数据的回传！

startActivity 与 startActivityForResult 启动方式的区别在这里就不作介绍了！

需要注意的是：
1、如果 ActivityB 在清单文件中声明了android:launchMode=”singleInstance”，这样 ActivityA、ActivityB 就不会再同一个栈中，导致setResult(RESULT_OK);失败。

2、this.startActivityForResult(intent, 200);

sourceCode：requestCode If >= 0, this code will be returned in onActivityResult() when the activity exits.  

译文：如果> = 0 requestCode，此代码将返回onactivityresult()活动时退出。
3、setResult(resultCode, data); // 设置返回数据，中的 resultCode是否大于0；

代码:

public class MainActivityA extends AppCompatActivity {    private TextView tv_info;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();    }    private void initView() {        tv_info = (TextView) findViewById(R.id.tv_info);    }    public void openActivity(View view){        Intent intent = new Intent(this, ActivityB.class);        Bundle bundle = new Bundle();        bundle.putInt("age", 24);        intent.putExtras(bundle);        startActivityForResult(intent, RequestCode.ACTIVITY_REQUETCODE);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        Log.i("wangly","请求码："+requestCode);        Log.i("wangly","返回的结果码："+ resultCode);        if (requestCode == RequestCode.ACTIVITY_REQUETCODE ){            switch (resultCode){                case RequestCode.ACTIVITY_RESULTCODE:                    String result = data.getStringExtra("result");                    sysOutString(result);                    break;            }        }        super.onActivityResult(requestCode, resultCode, data);    }    /**     * 输出打印结果     * @param object     */    private void sysOutString(Object object){        tv_info.setText(object.toString());        Toast.makeText(getApplicationContext(),object.toString(), Toast.LENGTH_LONG).show();    }}

2>ActivityB

public class ActivityB extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_second2);        TextView textView = (TextView) this.findViewById(R.id.textView);        Bundle bundle = getIntent().getExtras();        int age = bundle.getInt("age");        textView.setText("Activity A 传输的年龄：" + age);    }    public void closeActivity(View view) {        Intent intent = new Intent();        intent.putExtra("result", "经过查证你的年龄怎么有问题啊！！！！");        setResult(RequestCode.ACTIVITY_RESULTCODE, intent);        finish();    }}

管理请求码、结果码

public class RequestCode {    //Activity 请求码    public final static int ACTIVITY_REQUETCODE = 100;    //Activity 返回结果码    public final static int ACTIVITY_RESULTCODE = 20;}

控制台结果：