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第一次发帖，如有错误请见谅。也是Android的新手，我在试图找出共享偏好问题时遇到了问题。我声明我的常量如下

    private static SharedPreferences mSharedPreferences;
    static final String TWEET = null;

    static final String MEAL_ID = null;

我的共同偏好如下

    mSharedPreferences = getApplicationContext().getSharedPreferences(
            "MyPref", 0);

我的简单测试代码如下：

    String msgTemp = "testing";
long iDTest = 234;
Editor e = mSharedPreferences.edit();
e.putLong(MEAL_ID, iDTest);
e.putString(TWEET, msgTemp);
e.commit();
String tempMsg = mSharedPreferences.getString(TWEET, "");
long tempId = mSharedPreferences.getLong(MEAL_ID, 0);
    Toast.makeText(getApplicationContext(),
    "Msg: " + tempMsg + " " + "ID: " + tempId, Toast.LENGTH_LONG).show();

返回以下错误：

    03-25 15:47:41.386: E/AndroidRuntime(28321): java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Long03-25 15:47:41.386: E/AndroidRuntime(28321):    at android.app.SharedPreferencesImpl.getLong(SharedPreferencesImpl.java:228)

但是，如果我像这样切换代码中的 2 个“放置”行：

    String msgTemp = "testing";
long iDTest = 234;
Editor e = mSharedPreferences.edit();
e.putString(TWEET, msgTemp);
e.putLong(MEAL_ID, iDTest);
e.commit();
String tempMsg = mSharedPreferences.getString(TWEET, "");
long tempId = mSharedPreferences.getLong(MEAL_ID, 0);
    Toast.makeText(getApplicationContext(),
    "Msg: " + tempMsg + " " + "ID: " + tempId, Toast.LENGTH_LONG).show();

我收到以下错误：

    03-25 15:50:16.551: E/AndroidRuntime(28838): java.lang.ClassCastException:  java.lang.Long cannot be cast to java.lang.String 03-25 15:50:16.551: E/AndroidRuntime(28838):  at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:205)

所以在我看来，这些值以错误的顺序输入到偏好中，但我不知道为什么。我尝试在输入新值之前清除这些值，如下所示：

    String msgTemp = "testing";
long iDTest = 234;
Editor e = mSharedPreferences.edit();
e.remove(MEAL_ID);
e.remove(TWEET);
e.putLong(MEAL_ID, iDTest);
e.putString(TWEET, msgTemp);
e.commit();
String tempMsg = mSharedPreferences.getString(TWEET, "");
long tempId = mSharedPreferences.getLong(MEAL_ID, 0);
    Toast.makeText(getApplicationContext(),
    "Msg: " + tempMsg + " " + "ID: " + tempId, Toast.LENGTH_LONG).show();

但这也无济于事。任何人都可以为我阐明这一点吗？

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1 回答 1

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给你的常量值：

MEAL_ID = "meal_id"

于 2013-03-25T20:04:55.397 回答