1.需要传递参数：

public class Singleton{    private volatile static Singleton instance = null;    private int value = 0;    private Singleton(){        value = 1024;    }    public static Singleton getInstance(Context context){        if (instance == null){            synchronized (Singleton.class){                if (instance == null){                    instance = new Singleton(context.getApplicationContext());                }            }        }    }}

2.不需要传递参数

public class Singleton{    private Singleton(){}    public static Singleton getInstance(){         return SingletonHolder.instance;    }        private static class SingletonHolder{        private static final Singleton instance = new Singleton();    }