Question

我正在尝试从类中显示Toast消息，该类是customExceptionHandler。但我无法做到这一点。

我见过像Displaying a Toast message from the Application class这样的类似问题但是，它仍然没有解决我的问题。这里有什么我想念的。

我可以在Logcat中看到Log语句，但toast没有显示

public class MyApplication extends Application {

    private Thread.UncaughtExceptionHandler defaultUEH;

    private Thread.UncaughtExceptionHandler unCaughtExceptionHandler =
            new Thread.UncaughtExceptionHandler() {
                @Override
                public void uncaughtException(Thread thread, final Throwable ex) {
                    Log.e("Inside Run", "******************** Inside uncaughtException ***************" + ex.getMessage());
                    Toast.makeText(getApplicationContext(), ex.getMessage(), Toast.LENGTH_SHORT).show();
                }
            };

    public MyApplication() {
        defaultUEH = Thread.getDefaultUncaughtExceptionHandler();
        Thread.setDefaultUncaughtExceptionHandler(unCaughtExceptionHandler);
    }

}

我还尝试了另外一件事，我知道静态方法和变量不是最佳解决方案，但是我在一个util类中创建了一个静态方法，在静态变量中维护了一个活动上下文并用它来表示一个toast也没用？

喜欢

Util.showToast(ex.getMessage());

在uncaughtException（）方法中

Answer 1

Android Manifest文件，声明如下。

 <application android:name="com.example.MyApplication">

    </application>

然后写下课程：

public class MyApplication extends Application {

    private static Context context;

    public void onCreate() {
        super.onCreate();
        MyApplication.context = getApplicationContext();
    }

    public static Context getAppContext() {
        return MyApplication.context;
    }
}

现在，无处不在调用MyApplication.getAppContext()来静态获取应用程序上下文。

Answer 2

这对我有用

/**
 * createConstants Type
 */
type createConstantsType =
  <T extends string, U extends string>(namespace: T, prefix: U | null) =>
    <V extends string>(...constants: V[]) => Record<V, string>;

/**
 * function for creating namespaced constants
 * @param {String} namespace the namespace for the constant to create
 * @param {String} prefix the prefix for the constant to create
 * @returns {Object} namespaced constants for a module/feature
 * 
 *    // Common approach
 *    export const NAMESPACE = 'manual';
 *    export const SIDEBAR_TOGGLE = `${NAMESPACE}/SIDEBAR_TOGGLE`;
 *    export const SIDEBAR_OPEN = `${NAMESPACE}/SIDEBAR_OPEN`;
 *    export const SIDEBAR_CLOSE = `${NAMESPACE}/SIDEBAR_CLOSE`;
 *
 *    // Usage of this utility
 *    export const NAMESPACE = 'manual';
 *    export const SIDEBAR = createConstants(NAMESPACE, 'sidebar')('TOGGLE', 'OPEN', 'CLOSE');
 *
 *    // which will generate:
 *    SIDEBAR = {
 *      TOGGLE: 'manual/SIDEBAR_TOGGLE',
 *      OPEN: 'manual/SIDEBAR_OPEN',
 *      CLOSE: 'manual/SIDEBAR_CLOSE',
 *    }
 * 
 */
export const createConstants: createConstantsType =
  <T extends string, U extends string>(namespace: T, prefix: U | null = null) =>
    <V extends string>(...constants: V[]): Record<V, string> => (
    constants.reduce((result: Record<V, string>, constant: string): Record<V, string>  => ({
      [constant.toUpperCase()]:
        `${namespace}/${(prefix) ? `${prefix.toUpperCase()}_` : ''}${constant.toUpperCase()}`,
      ...result,
    }), {} as Record<V, string>)
  );

Answer 3

如果你想在你的应用程序calss中显示Toast而不是必须有一个上下文来显示Toast，那么你可以在构造函数中传递Context或获取活动实例

我没有尝试过这段代码，但你应该试试这个：

private static ApplicationContext instance;
/**
 * Your Constructor
 */
public MyApplication() {
    instance = this;
}

/**
 * Gets the application context.
 * @return the application context
 */
public static Context getContext() {
    if (instance == null) {
        instance = new ApplicationContext();
    }
    return instance;
}

       public static void showToast(String data) {
        Toast.makeText(getContext(), data,
                Toast.LENGTH_SHORT).show();
    }

显示UncaughtExceptionHandler中的Toast消息

3 个答案: