首页 > 代码库 > 关于HashCode对集合的影响之HashSet删除操作
关于HashCode对集合的影响之HashSet删除操作
package com.ArrayHashSet.a; class Person { private String name; private int age; public Person(String name, int age) { super(); this.name = name; this.age = age; } 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; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + age; result = prime * result + ((name == null) ? 0 : name.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; Person other = (Person) obj; if (age != other.age) return false; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } }
public class Test { public static void main(String[] args) { Collection c = new HashSet(); Person p = new Person("a",12); Person p2 = new Person("12",97); Person p3 = new Person("a",12); Person p4 = new Person("g",12); c.add(p4); c.add(p3); c.add(p2); c.add(p); //p2.setAge(2);//因为对p2的成员进行修改,导致hashcode被修改,在删除的时候 //找不到要删除的对象 c.remove(p2); for(Iterator it = c.iterator();it.hasNext();){ System.out.println(it.next().toString()); } } }
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