說明:一個標準類包含各種get,set方法,還要包括響應的各種構造函數
一Student類爲例,它包括姓名和年齡等屬性和方法,我們認爲當姓名和年齡相同是是同一個人,在使用HashMap存儲鍵和值的時候,以Student爲鍵,學生地址爲值,不能存入同一個人,所以需要重寫hashCode(),equals()方法。
package com.
public class Student{
private String name;
private int age;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Student student = (Student) o;
return age == student.age &&
name.equals(student.name);
}
@Override
public int hashCode() {
return name.hashCode()+ age*(30);
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}