preferenceActivity：保存的值作为整数 [英] PreferenceActivity: save value as integer

问题描述

使用我的preferences活动一个简单的的EditText preference ：

Using a simple EditTextPreference in my preferences activity:

<EditTextPreference
    android:key="SomeKey"
    android:title="@string/some_title"
    android:summary="..."
    android:numeric="integer"
    android:maxLength="2"
/>

有没有一种方法，此配置价值将被保存为整数？现在看来，它只是允许输入数字，但该值仍然保存为字符串：

Is there a way that this configuration value would be saved as integer? Seems now it just allows to enter numbers, but the value is still saved as string:

电话：

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
int value = preferences.getInt("SomeKey", -1);

抛出我 java.lang.ClassCastException：java.lang.String中和

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String value = preferences.getString("SomeKey", "-1");

检索值成功。

retrieves the value successfully.

如何让 preferenceActivity 默认保存的值作为整数？

How to make PreferenceActivity to save value as integer by default?

推荐答案

您可以扩展的EditText preference：

You could extend EditTextPreference:

public class IntEditTextPreference extends EditTextPreference {

    public IntEditTextPreference(Context context) {
        super(context);
    }

    public IntEditTextPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public IntEditTextPreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected String getPersistedString(String defaultReturnValue) {
        return String.valueOf(getPersistedInt(-1));
    }

    @Override
    protected boolean persistString(String value) {
        return persistInt(Integer.valueOf(value));
    }
}

这将是更好地覆盖onSetInitialValue（）和的setText（）方法，但你会复制一些code从基类。上述方案是simplier，但它是相当棘手 - 弦的方法做一些与整数。尽量不要扩展此类进一步的; - ）

It would be better to overwrite onSetInitialValue() and setText() methods, but then you would have to copy some code from a base class. Above solution is simplier, but it's quite tricky - "string" methods do something with ints. Try to not extend this class further ;-)

您可以通过使用它从XML

You could use it from XML by:

<package.name.IntEditTextPreference
    android:key="SomeKey"
    android:title="@string/some_title"
    android:summary="..."
    android:numeric="integer"
    android:maxLength="2"
/>

这篇关于preferenceActivity：保存的值作为整数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！