@Test    public void test02() {        StringBuffer sb = new StringBuffer();        sb.append('a');        sb.append(11);        System.out.println(sb.toString());        System.out.println("======字符串的引用==========");        String s1 = new String();        s1="123";        String s2 = new String();        s2="123";        System.out.println(s1);        System.out.println(s2);        System.out.println(s1==s2);        System.out.println(s1=s2);        System.out.println("======引用对象类型==========");        Person p = new Person();        p.id = 1;        p.name = "zhangsan";        Person p2 = new Person();        p2.id = 1;        p2.name = "zhangsan";        System.out.println(p);        System.out.println(p2);        System.out.println(p==p2);        System.out.println(p.equals(p2));        System.out.println(p.equals(p));        System.out.println(p.name.equals(p2.name));        System.out.println(p=p2);    }    class Person{            private int id;            private String name;        @Override        public String toString() {            return "Person{" +                    "id=" + id +                    ", name='" + name + '\'' +                    '}';        }    }

　　都是很基础的东西

今天是无聊了，这些基础的东西跑跑也是好的。

 造成这些的原因，是与JVM内存机制有关系。

String 常量池

引用对象类型存在于栈Stack中