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Java
import java.util.HashSet;
import java.util.Iterator;

public class Example07 {
    public static void main(String[] args) {
        HashSet set = new HashSet(); // 創(chuàng)建HashSet集合
        set.add("張三"); // 向該Set集合中添加字符串
        set.add("李四");
        set.add("王五");
        set.add("李四"); // 向該Set集合中添加重復(fù)元素
        Iterator it = set.iterator(); // 獲取Iterator對(duì)象
        while (it.hasNext()) { // 通過(guò)while循環(huán)，判斷集合中是否有元素
            Object obj = it.next(); // 如果有元素，就通過(guò)迭代器的next()方法獲取元素
            System.out.println(obj);
        }
    }
}

Java
import java.util.HashSet;

class Student {
    String id;
    String name;

          // 創(chuàng)建構(gòu)造方法
    public Student(String id, String name) {
        this.id = id;
        this.name = name;
    }

          // 重寫(xiě)toString()方法
    @Override
    public String toString() {
        return id + ":" + name;
    }
}
public class Example08 {
    public static void main(String[] args) {
        HashSet hs = new HashSet(); // 創(chuàng)建HashSet集合
        Student stu1 = new Student("1", "張三"); // 創(chuàng)建Student對(duì)象
        Student stu2 = new Student("2", "李四");
        Student stu3 = new Student("2", "李四");
        hs.add(stu1);
        hs.add(stu2);
        hs.add(stu3);
        System.out.println(hs);
    }
}

Java
import java.util.HashSet;
import java.util.Objects;

class Student {
    String id;
    String name;

    // 創(chuàng)建構(gòu)造方法
    public Student(String id, String name) {
        this.id = id;
        this.name = name;
    }

    // 重寫(xiě)toString()方法
    @Override
    public String toString() {
        return id + ":" + name;
    }

    // 重寫(xiě)hashCode方法
    @Override
    public int hashCode() {
        return id.hashCode(); // 返回id屬性的哈希值
    }

    // 重寫(xiě)equals方法
    @Override
    public boolean equals(Object o) {
        // 判斷是否是同一個(gè)對(duì)象，如果是，直接返回true
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        // 判斷對(duì)象是否為Student類型
        if (!(o instanceof Student)) return false;
        // 將對(duì)象強(qiáng)轉(zhuǎn)為Student類型
        Student student = (Student) o;
        // return (id == student.id) || (id != null && id.equals(student.id));
        return Objects.equals(id, student.id);
    }
}

public class Example09 {
    public static void main(String[] args) {
        HashSet hs = new HashSet(); // 創(chuàng)建HashSet集合
        Student stu1 = new Student("1", "張三"); // 創(chuàng)建Student對(duì)象
        Student stu2 = new Student("2", "李四");
        Student stu3 = new Student("2", "李四");
        hs.add(stu1);
        hs.add(stu2);
        hs.add(stu3);
        System.out.println(hs);
    }
}

Java
import java.util.Iterator;
import java.util.LinkedHashSet;

public class Example10 {
    public static void main(String[] args) {
        LinkedHashSet set = new LinkedHashSet();
        set.add("張三"); // 向該Set集合中添加字符串
        set.add("李四");
        set.add("王五");
        Iterator it = set.iterator(); // 獲取Iterator對(duì)象
        while (it.hasNext()) { // 通過(guò)while循環(huán)，判斷集合中是否有元素
            Object obj = it.next();
            System.out.println(obj);
        }
    }
}