单例模式的饿汉式实现

1、私有化类的构造器

2、创建类的对象

3、提供公共的静态方法，返回类的对象

4、要求此对象也必须声明为静态的

public class bank {

	private bank() {

	}

	private static bank instance = new bank();

	private static bank getInstance() {
		return instance;
	}

	public static void main(String[] args) {
		bank.getInstance();
	}

}

下面是测试代码

public class Bank {

	private Bank() {

	}

	private static Bank instance = new Bank();

	private static Bank getInstance() {
		return instance;
	}

	public static void main(String[] args) {
		Bank bank1 = Bank.getInstance();
		Bank bank2 = Bank.getInstance();
		System.out.println(bank1 == bank2);
	}
}