利用两种方式分别实现单例模式（懒汉式、饿汉式）

package testsingle;//实现单例的两种方式
public class TestMySingle {public static void main(String[] args) {ClassA ca1 = ClassA.getClassA();ClassA ca2 = ClassA.getClassA();System.out.println(ca1==ca2);ClassB cb1 = ClassB.getClassB();ClassB cb2 = ClassB.getClassB();System.out.println(cb1==cb2);}
}
class ClassA{       //饿汉式private static final ClassA ca = new ClassA();private ClassA(){}public static ClassA getClassA(){return ca;}
}
class ClassB{       //懒汉式private static  ClassB cb ;private ClassB(){}public synchronized static ClassB getClassB(){if(cb==null){cb = new ClassB();}return cb;}
}