一：

public class Singleton {
    private Singleton() {
    }

    private static class SingletonHolder {
        public final static Singleton SINGLETON = new Singleton();
    }

    public final static Singleton getSingleton() {
        return SingletonHolder.SINGLETON;
    }
}

Singleton SINGLETON = new Singleton();采用的是

递归写法

二：

匿名类的使用：

BroadcastUtil.registerReceiver(this, new BroadcastUtil.IReceiver() {
            @Override
            public void onReceive(Context ctx, Intent intent) {
                Log.v("-->", "Bingo");
            }
        }, BroadcastFlag);

等价于：

BroadcastUtil.IReceiver iReceiver = new BroadcastUtil.IReceiver() {
            @Override
            public void onReceive(Context ctx, Intent intent) {
                Log.v("-->", "Bingo");
            }
        };
BroadcastUtil.registerReceiver(this, iReceiver, BroadcastFlag);