java程式語言Set集合方法示範

標籤：黑馬程式員   語言   

java程式語言Set集合方法示範

import java.util.Collection;import java.util.Comparator;import java.util.HashSet;import java.util.Iterator;import java.util.Set;public class HashSetDemos {public static void main(String[] args) {// 建立一個Set類的集合Set   st = new HashSet();st.add("abc1");st.add("abc2");st.add("abc1");st.add("abc2");//輸出結果只會有 abc1  和abc2  不允許元素重複Iterator it = st.iterator();while(it.hasNext()){System.out.println(it.next());}st.removeAll(st);st.add(new Studenti("lisi",23));st.add(new Studenti("lisi",24));st.add(new Studenti("lisan",22));st.add(new Studenti("lisan",20));Iterator its = st.iterator();while(its.hasNext()){Studenti s = (Studenti) its.next();System.out.println(s.getName()+"  "+s.getAge());}}}class Studenti{private String name;private int age;Studenti(String name ,int age){this.name=name;this.age = age;}public int getAge(){return age;}public String getName(){return name;}public String toString(){return "the student name : +name "+"  and  age is : "+ age;}public int hashCode(){return name.hashCode()+age*10;}public boolean equals(Object obj){ if(this == obj)             return true ;//同一個對象放兩次，直接返回true             if(!(obj instanceof Studenti))             throw new ClassCastException("類型錯誤");       Studenti p = (Studenti)obj;       return this .name.equals(p.name) && this.age == p.age;}}

運行程式：

java程式語言Set集合方法示範