Question

我有这段简单的代码：

        SharedPreferences settings = getSharedPreferences(Constants.USER_DETAILS, 0);
        SharedPreferences.Editor editor = settings.edit();

        //editor.putLong(Constants.USER_DETAILS_SIGNEDINON, registerResponse.getSignedInOn()); // signed in on

        editor.putLong(Constants.USER_DETAILS_SIGNEDINON, 1); // signed in on
        long test = settings.getLong(Constants.USER_DETAILS_SIGNEDINON, 2);

        if (settings.edit().commit()) {
            System.out.print("ok");
        } else {
            System.out.print("not ok");
        }

你可以看到我一直在玩，以了解发生了什么。

所以，我检查了/ data / data / ...并且确实创建了首选项文件，但它是空的（只是Map标签）

测试long变量返回2，即使我之前将它设置为1。提交返回true。

我错过了什么吗？

我设置了uses-permission android：name = android.permission.WRITE_EXTERNAL_STORAGE 虽然我相信只有在我真正做外部存储时才需要这样做。

的问候。大卫。

Answer 1

我遇到的一件事是，您无法继续调用pref.edit（）并期望您的更改仍然存在。似乎每次调用pref.edit（）都会产生一个新的编辑器（而不是单例）。

不会坚持：

pref.edit().remove("key"); // new editor created
pref.edit().commit();      // new editor created

将坚持：

Editor edit=pref.edit();   // new editor created
edit.remove("key");        // same editor used
edit.commit();             // same editor used

Answer 2

试试这段代码。

    SharedPreferences settings = getSharedPreferences(Constants.USER_DETAILS, 0);
    SharedPreferences.Editor editor = settings.edit();

    //editor.putLong(Constants.USER_DETAILS_SIGNEDINON, registerResponse.getSignedInOn()); // signed in on

    editor.putLong(Constants.USER_DETAILS_SIGNEDINON, 1); // signed in on

    if (editor.commit()) {
        System.out.print("ok");
    } else {
        System.out.print("not ok");
    }
    long test = settings.getLong(Constants.USER_DETAILS_SIGNEDINON, 2);

Answer 3

SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref",  0);        0 - for private mode
Editor editor = pref.edit();
editor.putBoolean("key_name", true); // Storing boolean - true/false
editor.putString("key_name", "string value"); // Storing string
// returns stored preference value
// If value is not present return second param value - In this case null
pref.getString("key_name", null); // getting String
pref.getInt("key_name", null); // getting Integer
editor.remove("name"); // will delete key name
editor.remove("email"); // will delete key email

editor.commit(); // commit changes
editor.clear();
editor.commit(); // commit changes

SharedPreferences和Emulator

3 个答案: