java子类继承父类重写tostring和重写equals方法

以你之姓@ 2023-05-21 10:26 9阅读 0赞

用学生的输出为例子，子类继承父类，然后在子类中新定义一个属性并可以给父类属性赋值，以及重写tostring和重写equals方法。  
![在这里插入图片描述][20200420203510322.png]  
demo测试

package Student;
    
    public class demo {
        
    
        public static void main(String[] args) {
        
    	// TODO Auto-generated method stub
    
    	Undergraduate s1 = new Undergraduate("张三", 30, "专科");
    
    	Undergraduate s2 = new Undergraduate("张三", 30, "本科");
    	Undergraduate s3 = new Undergraduate("张三", 30, "本科");
    	System.out.println(s1.equals(s2));
    	System.out.println(s3.equals(s2));
    	System.out.println(s1);
    	System.out.println(s2);
    	System.out.println(s3);
    
        }
    
    }

父类定义属性

package Student;
    
    public class Student {
        
        public String name;
        public int age;
    
        public Student() {
        
    	// TODO Auto-generated constructor stub
        }
    
        public Student(String name, int age) {
        
    	this.name = name;
    	this.age = age;
        }
    
        public void show() {
        
    	System.out.println(name + "," + age);
    
        }
    
    }

子类定义新属性，重写函数

package Student;
    
    public class Undergraduate extends Student {
        
        public String degrre;
    
        public Undergraduate(String name, int age, String degrre) {
        
    	super(name, age);
    	this.degrre = degrre;
        }
    
        @Override
        public int hashCode() {
        
    	final int prime = 31;
    	int result = 1;
    	result = prime * result + ((degrre == null) ? 0 : degrre.hashCode());
    	return result;
        }
    
        @Override
        public boolean equals(Object obj) {
        
    	if (this == obj)
    	    return true;
    	if (obj == null)
    	    return false;
    	if (getClass() != obj.getClass())
    	    return false;
    	Undergraduate other = (Undergraduate) obj;
    	if (degrre == null) {
        
    	    if (other.degrre != null)
    		return false;
    	} else if (!degrre.equals(other.degrre))
    	    return false;
    	return true;
        }
    
        @Override
        public String toString() {
        
    	return "degrre=" + degrre + ", name=" + name + ", age=" + age + "";
        }
    
        public void show() {
        
    	System.out.println(name + "," + degrre + "," + age);
    
        }
    }

运行结果展示  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5neXVud2VpX0Jsb2c_size_16_color_FFFFFF_t_70]

[20200420203510322.png]: /images/20230521/c7391b62d73e476d9d4aecbedc38f676.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5neXVud2VpX0Jsb2c_size_16_color_FFFFFF_t_70]: /images/20230521/d65e1a07573a4efe9548c426e62f3e7b.png