JavaSE 高级 第02节 Object类

2016-07-24

1,Object类的常用方法介绍

finalize() gc() 这两个方法我们不要试图去控制，他们是由Java虚拟机

控制的，我们只能建议gc()去执行finalize()，但具体是否执行，只有

Java虚拟机才知道，因为这是有Java虚拟机的算法决定的。

package com.java1995;

public class TestClone {

    public static void main(String[] args) {
        Student s1 = new Student();
        s1.setName("老王");
        s1.setAge(29);
        s1.setSex("男");

        System.out.println(s1);

        try {
            Student s2 = s1.clone();
            System.out.println(s2);
            System.out.println(s1 == s2);
        } catch (CloneNotSupportedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

class Student implements Cloneable {

    private String name;
    private String sex;
    private int age;

    public Student clone() throws CloneNotSupportedException {
        return (Student) super.clone();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student [name=" + name + ", sex=" + sex + ", age=" + age + "]";
    }

}

package com.java1995;

public class TestEquals_HashCode {

    public static void main(String[] args) {
        Object o1 = new Object();
        Object o2 = new Object();
        System.out.println(o1.equals(o2));
        System.out.println(o1.hashCode() + "," + o2.hashCode());

    }
}

package com.java1995;

public class TestFinalize {

    private int id;

    public TestFinalize(int id) {
        this.id = id;
    }

    public static void main(String[] args) {
        for (int i = 0; i < 10000; i++) {
            new TestFinalize(i);
            /**
             * 建议虚拟机执行垃圾回收，但是不保证执行， 也不保证回收所有垃圾。
             */
            System.gc();
        }
    }

    @Override
    public void finalize() {
        System.out.println(id + "正在被执行finalize方法");
    }
}

【参考资料】

[1] Java轻松入门经典教程【完整版】