android - 使用共享首选项编辑器

Question

我正在慢慢阅读一本 Android 学习书，并获得了以下代码来分配用户数据：

package com.androidbook.triviaquiz;

import android.app.Activity;
import android.content.SharedPreferences;

public class QuizActivity extends Activity {
    public static final String GAME_PREFERENCES = "GamePrefs";
    SharedPreferences settings = getSharedPreferences(GAME_PREFERENCES, MODE_PRIVATE);
    SharedPreferences.Editor prefEditor = settings.edit();
    prefeditor.putString("UserName", "John Doe"); //**syntax error on tokens**
    prefEditor.putInt("UserAge", 22); //**syntax error on tokens**
    prefEditor.commit();
}

但是，我收到一个错误（带有注释的行），它强调了句点并说“错位构造”，并且强调了“删除这些标记”的论点。我已经在其他应用程序中以相同的格式看到了这一点，我不明白出了什么问题。

Answer 1

编辑：当然！这些语句不能直接放入该级别的类中，并且必须在方法中，如下所示：

public class QuizActivity extends Activity {
    public static final String GAME_PREFERENCES = "GamePrefs";

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

        SharedPreferences settings = getSharedPreferences(GAME_PREFERENCES, MODE_PRIVATE);
        SharedPreferences.Editor prefEditor = settings.edit();
        prefEditor.putString("UserName", "John Doe");
        prefEditor.putInt("UserAge", 22);
        prefEditor.putString("Gender", "Male");
        prefEditor.commit();
    }
}

Answer 2

我认为您可能错过了 OnCreate() 方法，请确保您应该将共享首选项放在您的 OnCreate() 方法中...我刚刚编辑了您的代码通过它

请通过代码...下面

public class A extends Activity {
static SharedPreferences settings;
 public static final String PREFS_NAME = "YourPrefName";

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        settings = getSharedPreferences(PREFS_NAME, 0);
Log.v("UserName"," - "+settings.getString("username","android"));
SharedPreferences.Editor editor = settings.edit();          
            editor.putString("username","Change Android");          
            editor.commit();

Log.v("UserName after changed editing preference key value"," - "+settings.getString("username","android"));


}

}

Answer 3

SharedPreferences 将在 onCreate() 方法旁边工作，只要它有上下文：

SharedPreferences settings = getAplicationContext().getSharedPreferences(GAME_PREFERENCES, MODE_PRIVATE);