java ⼦类继承⽗类重写tostring 和重写equals ⽅法
⽤学⽣的输出为例⼦，⼦⽗类，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。demo测试
⽗类定义属性
⼦类定义新属性，重写函数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);    }}
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java的tostring方法11
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21package  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 );    }}
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运⾏结果展⽰package  Student ;public  class  Undergraduate extends  Student {    public  String degr
re ;    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 );    }}
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