当设备方向改变时 onCreate 方法不断被调用

发布于 12-26 16:13 字数 477 浏览 3 评论 0原文

我有一个 AsyncTask，它在我的 Main Activity 中被调用 onCreate()。在同一个 Activity 中，如果方向发生变化，AsyncTask 会再次被调用。如何防止这种情况发生，或者如何重组我的程序以避免这种情况发生？

public class Main extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.pages);
        StartProcess sProcess = new StartProcess();
        sProcess.execute(this);
    }
}

原文

I have an AsyncTask which gets called onCreate() in my Main Activity. In the same Activity if the orientation changes the AsyncTask gets called again. How do I prevent this from happening or how do I restructure my program to avoid this happening?

public class Main extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.pages);
        StartProcess sProcess = new StartProcess();
        sProcess.execute(this);
    }
}

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浅浅2025-01-02 16:13:01

您应该检查处理运行时更改

您可以使用

在配置更改期间保留对象

允许您的 Activity 在配置更改时重新启动，但将有状态对象携带到 Activity 的新实例。

处理配置改变自己

防止系统在某些配置更改期间重新启动您的 Activity，但在配置发生更改时接收回调，以便您可以根据需要手动更新您的 Activity。

要在运行时配置更改期间保留对象：

重写onRetainNonConfigurationInstance() 方法以返回您想要保留的对象。

当您的 Activity 再次创建时，调用 getLastNonConfigurationInstance() 来恢复您的对象。

@Override
public Object onRetainNonConfigurationInstance() {
    final MyDataObject data = collectMyLoadedData();
    return data;
}

保留在OnCreate中；

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    final MyDataObject data = (MyDataObject) getLastNonConfigurationInstance();
    if (data == null) {
        data = loadMyData();
    }
    ...
}

或者只需将此代码添加到您的活动清单中

 android:screenOrientation="portrait"

或

 android:screenOrientation="landscape"

You should check Handling Run Time Changes

You can Handle either by using

Retain an object during a configuration change

Allow your activity to restart when a configuration changes, but carry a stateful Object to the new instance of your activity.

Handle the configuration change yourself

Prevent the system from restarting your activity during certain configuration changes, but receive a callback when the configurations do change, so that you can manually update your activity as necessary.

To retain an object during a runtime configuration change:

Override the onRetainNonConfigurationInstance() method to return the object you would like to retain.

When your activity is created again, call getLastNonConfigurationInstance() to recover your object.

@Override
public Object onRetainNonConfigurationInstance() {
    final MyDataObject data = collectMyLoadedData();
    return data;
}

Retain in OnCreate ;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    final MyDataObject data = (MyDataObject) getLastNonConfigurationInstance();
    if (data == null) {
        data = loadMyData();
    }
    ...
}

Or simply add this code in you Manifest of you Activity