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重拾android路(十一) 设计模式

admin 11月 11, 2020 0

设计模式在Android中的应用

饿汉模式

public class {
    private (){}
    private static App app = new App();
    public static App getApp(){
        return app;
    }
}

懒汉模式

public class {
    private (){}
    private static App app = null;
    public static synchronized App getApp(){
        if(app == null){
            app = new App();
        }
        return app;
    }
}

另外一种

public class {
    private App(){}
    private volatile static App app;
    public static App getApp(){
        if(app ==  null){
            synchronized(App.class){
                if(app == null){
                    app = new App();
                }
            }
        }
        return app;
    }
}

静态内部类

public class App{
    private static class GetAppInstance{
        public static App mApp = new App();
    }
    private App(){}
    public static App getApp(){
        return GetAppInstance.mApp;
    }
}