Question

public class MainActivity extends BaseActivity{

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

    }

    @OnClick(R.id.go)
    public void btnClick() {
        startActivity(new Intent(this, SecondActivity.class));

    }
}

-

public class SecondActivity extends BaseActivity implements TestAsyncTask.Callbacks{

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        ButterKnife.bind(this);
    }

    @OnClick(R.id.btn)
    public void onClick() {
        new TestAsyncTask(this).execute();
    }

    @Override
    public void onResult(String result) {
        finish();
    }
}

-

public class TestAsyncTask extends AsyncTask<Void, Void, String> {

    private WeakReference<Callbacks> mCallbacks;

    public TestAsyncTask(Callbacks callbacks) {
        mCallbacks = new WeakReference<Callbacks>(callbacks);
    }

    public interface Callbacks {
        void onResult(String result);
    }

    @Override
    protected String doInBackground(Void... params) {
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "WOW";
    }

    @Override
    protected void onPostExecute(String result) {
        Callbacks callbacks = mCallbacks.get();
        if(callbacks != null) {
            callbacks.onResult(result);
        }
    }
}

MainActivity启动SecondActivity。 SecondActivity启动一个AsyncTask，它在十秒后回调onResult。如果我在回调和启动asynctask之间旋转屏幕，则会创建一个新的SecondActivity。因此onResult将被称为旧的SecondActivity。但是为什么finish（）完成新的？

我知道编写这样的代码很糟糕。应该取消asynctask或其他东西。但有趣的是为什么会发生这种情况。这是一种未定义的行为吗？

如果您想重现，请考虑克隆https://github.com/guliash/AndroidExplorer/tree/test

完成已经破坏的活动

0 个答案: