Question

告诉我 - 我想在一个单独的类中读取DefaultSharedPreferences设置。并且已经有其他Activity从中读取数据（在任何Activity数据中都会被读取，但是想要通过一个单独的类来实现它，每个Activity都不会在每个Activity中读取它们）。代码 - Main.java

public class Main extends Activity{

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

    Test t = new Test();

    String z = t.getAa();
    Toast.makeText(Main.this, z, Toast.LENGTH_LONG).show();
    }

 }

代码 - Test.java

public class Test extends PreferenceActivity {

private String aa;
private String EdittextListPreferenceFont;

public String getAa() {
            addPreferencesFromResource(R.xml.preferences);

    SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(getBaseContext());

    EdittextListPreferenceFont = prefs.getString("edittext_font",
            getString(R.string.font_default));
            aa = EdittextListPreferenceFont;
    return aa;
}

}

LogCat eclipse

12-29 19:16:13.016: E/AndroidRuntime(5804): FATAL EXCEPTION: main
12-29 19:16:13.016: E/AndroidRuntime(5804): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.game.invasion/com.game.invasion.Main}: java.lang.RuntimeException: This should be called after super.onCreate.
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread.access$1500(ActivityThread.java:123)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.os.Looper.loop(Looper.java:130)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread.main(ActivityThread.java:3835)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at java.lang.reflect.Method.invokeNative(Native Method)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at java.lang.reflect.Method.invoke(Method.java:507)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at dalvik.system.NativeStart.main(Native Method)
12-29 19:16:13.016: E/AndroidRuntime(5804): Caused by: java.lang.RuntimeException: This should be called after super.onCreate.
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.preference.PreferenceActivity.requirePreferenceManager(PreferenceActivity.java:212)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:260)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at com.game.invasion.Test.getAa(Test.java:19)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at com.game.invasion.Main.onCreate(Main.java:45)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-29 19:16:13.016: E/AndroidRuntime(5804):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722)

我将很感激帮助或链接在哪里阅读它。 PS - 对不起，谷歌翻译

Answer 1

我不确定，你想要实现的目标。

但是，PreferenceActivity是一个实现UI以与首选项交互的类。以下是说明：http://developer.android.com/reference/android/preference/PreferenceActivity.html

特别是不要使用构造函数来创建一个，但start就像使用intent的任何其他活动一样。

如果您只需要访问存储的共享首选项值，则无需子类化任何特殊类：

public class PreferenceProxy {

    private final SharedPreferences prefs;

    public PreferenceProxy(final Context ctx) {
       this. prefs = PreferenceManager.getDefaultSharedPreferences(ctx));
    }

   public String getAa() {
       prefs.getString("edittext_font", null); // or any other default value, I did not understand your code snippet
    }

}

但是，我怀疑代理是值得的。我建议创建一个界面来定义键，比如“edittext_font”。这降低了密钥中拼写错误的风险。此外，您可能希望只有一个点来获取首选项，例如您的应用程序对象或主活动中的静态方法接受Context（如示例中的构造函数）。但是，不要为每个首选项实现一个方法，除非你因为复杂的默认值管理或其他原因从中获得了某些东西。

整个应用程序的DefaultSharedPreferences设置在单独的类中

1 个答案: