JAVA中Set集合--HashSet的使用

一、使用HashSet添加一个String类型的值：

public static void hashSet1(){
HashSet hashSet = new HashSet();
hashSet.add("java001");
hashSet.add("java01");
hashSet.add("java011");
hashSet.add("java002");
hashSet.add("java004");

//使用常用迭代器获取输出内容
Iterator iterator = hashSet.iterator();
while (iterator.hasNext()) {
String next = iterator.next();
System.out.println(next);
}
}

二、使用HashSet添加一个对象：

public static void hashSet2(){
HashSet hashSet = new HashSet();
hashSet.add(new Student("zhangsan1", 21));
hashSet.add(new Student("zhangsan1", 21));
hashSet.add(new Student("zhangsan2", 21));
hashSet.add(new Student("zhangsan3", 23));
hashSet.add(new Student("zhangsan4", 24));
//使用常用迭代器获取值
Iterator iterator = hashSet.iterator();
while (iterator.hasNext()) {
Student next = (Student) iterator.next();
System.out.println(next.getName() + " " + next.getAge());
}
}

上面使用到的Student对象类：

class Student {
private String name;
private int age;

public Student(String name, int age) {
this.name = name;
this.age = age;
}

//复写hashCode方法
@Override
public int hashCode() {

return 60;
}

//复写equals方法
@Override
public boolean equals(Object arg0) {
if (!(arg0 instanceof Student)) {
return false;
}
Student studet = (Student) arg0;
return this.name.equals(studet.name) && this.age == studet.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;
}
}

最后使用调用main方法得出结果：

java004
java002
java011
java001
java01
-------------------------
zhangsan1 21
zhangsan2 21
zhangsan3 23
zhangsan4 24