切换按钮上的方向改变状态改变 [英] ToggleButton change state on orientation changed

问题描述

我有一个的CustomButton 类（扩展的LinearLayout ），在那里我膨胀，其中包含一个<$ C $布局C>切换按钮（在现实中，这是比较复杂的，但我在这里简单的问题）。

I have a CustomButton class (extends LinearLayout) where I inflate a layout which contains a ToggleButton (in reality this is more complex, but I simplified here the problem).

public class CustomButton extends LinearLayout {

    private ToggleButton toggleOnOffButton;

    public CustomButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        LayoutInflater.from(context).inflate(R.layout.custom_button_layout, this);
    }

    @Override
    protected void onFinishInflate() {
        toggleOnOffButton = (ToggleButton) findViewById(R.id.toggle_on_off_button);
        super.onFinishInflate();
    }

    public ToggleButton getToggleOnOffButton() {
        return toggleOnOffButton;
    }
}

custom_button_layout.xml

custom_button_layout.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content">

    <ToggleButton android:id="@+id/toggle_on_off_button"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:textOff="Off"
                  android:textOn="On"
                  android:layout_alignParentRight="true"
            />
</RelativeLayout>

我有我的地方用充气2 的CustomButton -s一个布局的活动。
第一个切换按钮的开/关状态保存在共享preferences，我从那里的onCreate 方法装载的价值。

I have an activity where I inflate an layout with 2 CustomButton-s. The on/off state of the first toggleButton is saved in shared preferences and I load the value from there in onCreate method.

public class FirstActivity extends Activity
{
    private CustomButton customButton;
    private ToggleButton toggleBut;

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

        customButton = (CustomButton)findViewById(R.id.toggleButton);
        toggleBut = customButton.getToggleOnOffButton();

        boolean saved = loadPreferences("toggleBut");
        toggleBut.setChecked(saved);
        toggleBut.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                boolean checked = toggleBut.isChecked();
                savePreferences("toggleBut", checked);
            }
        });
    }

    private void savePreferences(String key, boolean value){
        SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putBoolean(key, value);
        editor.commit();
    }

    private boolean loadPreferences(String key){
        SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
        return sharedPreferences.getBoolean(key, true);
    }
}

main.xml中

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"> 
    <com.example.example.cs.ssd.custom.CustomButton
            android:id="@+id/toggleButton"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            />

    <com.example.example.cs.ssd.custom.CustomButton
            android:id="@+id/toggleButton2"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            />
</LinearLayout>

当我启动应用程序的第一个切换按钮接通。当我改变屏幕的方向，自动将第一切换按钮变为关闭，甚至已保存的值真正，被称为 toggleBut.setChecked（保存）; ，我认为这与做 CutomButton 我如果因为创建的main.xml 布局只包含1 的CustomButton 这个问题不会重现。
我不知道我在做什么错了？
下面是与上面的code中的归档（作为一个项目）：存档

When I start the application the first toggleButton is ON. When I change the orientation of the screen, automatically the first toggleButton become Off, even saved has value true and is called toggleBut.setChecked(saved); and I think this has to do with the CutomButton I've created because if the main.xml layout contains only 1 CustomButton this problem does not reproduce. I'm not sure what I'm doing wrong... Here is the archive with the above code (as a project): archive

推荐答案

如果你希望你的CustomButton保留后改变方向时只需重写的onSaveInstanceState（）和onRestoreInstanceState（）。其当前状态

If you want your CustomButton to retain its current state after an orientation change simply override onSaveInstanceState() and onRestoreInstanceState().

一个解决方案

我通过你的code跑去，发现onActivityCreated（后变更后 toggleBut 的状态），但在onStart（）之前。为了避免上述任何一种方法覆盖您切换设置，我干脆搬离onViewCreated（）这些行：

I ran through your code and noticed that toggleBut's state was being changed after onActivityCreated() but before onStart(). To avoid having any of these methods override your toggle settings, I simply moved these lines from onViewCreated():

boolean saved = loadPreferences("toggleBut");
toggleBut.setChecked(saved);

和把它们放在onResume（）。希望帮助！

and put them in onResume(). Hope that helps!

更好的解决方案

当系统试图恢复默认您的切换按钮的设置都被覆盖 saveInstanceState ，大概在Fragment.onActivityCreated（）。

Your ToggleButton setting are being overwritten when the system tries to restore the default saveInstanceState, probably in Fragment.onActivityCreated().

在的CustomButton，覆盖这些功能，像这样：

In CustomButton, override these functions like so:

@Override
protected Parcelable onSaveInstanceState() {
    Bundle state = new Bundle();
    state.putParcelable("default", super.onSaveInstanceState());
    state.putParcelable("toggle", toggleOnOffButton.onSaveInstanceState());
    return state;
}

@Override
protected void onRestoreInstanceState(Parcelable state) {
    Bundle bundle = (Bundle) state;
    super.onRestoreInstanceState(bundle.getParcelable("default"));
    toggleOnOffButton.onRestoreInstanceState(bundle.getParcelable("toggle"));
};

理解，系统仍然会改变切换按钮的状态，没有一件事。但让我试着解释一下，发生的事：

Understand that the system will still change the ToggleButton states, without the one more thing. But let me try to explain what;s happening:

• onActivityCreated（捆绑savedInstanceState）通过它的 savedInstanceState 的每一个布局元素通过调用onRestoreInstanceState（捆绑savedInstanceState）` 。


• onRestoreInstanceState（）的布局的根元素开始的第一和横穿了布局的层次结构（在这种情况下，它设置每个切换按钮最后的选中状态）。


• 由于默认的方法显然不工作，我们需要定义为的ToggleButtons我们自己保存/恢复方法。否则，我们所做的任何更改的系统调用onRestoreInstanceState（前）将被系统再次改变...

• onActivityCreated(Bundle savedInstanceState) passes it's savedInstanceState to every layout element by calling 'onRestoreInstanceState(Bundle savedInstanceState)`.
• onRestoreInstanceState() begins with the layout's root element first and traverses up the layout's hierarchy (in this case it sets the checked state of each ToggleButton last).
• Since the default methods are clearly not working, we need to define our own save / restore method for the ToggleButtons. Otherwise any changes we make before the system calls onRestoreInstanceState() will be changed again by the system...

所以，最后我们将通过添加以下行来CustomButton.onFinishInflate（）排除此默认行为的ToggleButtons

So, lastly we will exclude the ToggleButtons from this default behavior by adding the following line to CustomButton.onFinishInflate():

toggleOnOffButton.setSaveEnabled(false);

瞧，您的CustomButtons自动保留其状态。

Voila, your CustomButtons automatically retain their state.

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