HashSet和TreeSet

src/chapter6/Example08.java

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+package chapter6;
+
+import java.util.HashSet;
+import java.util.Iterator;
+
+class Student implements Comparable<Student> {
+    String id;
+    String name;
+    int height;
+
+    public Student(String id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public void setHeight(int height) {
+        this.height = height;
+    }
+
+    public String toString() {
+        return id + ":" + name;
+    }
+
+    public int hashCode() {
+        return id.hashCode();
+    }
+
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!(obj instanceof Student)) {
+            return false;
+        }
+
+        Student other = (Student) obj;
+        return this.id.equals(other.id);
+    }
+
+    public int compareTo(Student other) {
+        if (this.height > other.height) {
+            return 1; // 返回正数：表示"我"比"你"大
+        } else if (this.height < other.height) {
+            return -1;  // 返回负数：表示"我"比"你"小
+        } else {
+            return 0; // 返回0：表示"我"和"你"一样大
+        }
+    }
+}
+
+public class Example08 {
+    public static void main(String[] args) {
+        HashSet<Student> students = new HashSet<>();
+
+        Student s1 = new Student("1", "张三");
+        Student s2 = new Student("2", "李四");
+        Student s3 = new Student("2", "李四");
+        Student s4 = new Student("3", "王五");
+
+        students.add(s3);
+        students.add(s4);
+        students.add(s1);
+        students.add(s2);
+
+        Iterator<Student> iterator = students.iterator();
+        while (iterator.hasNext()) {
+            Student student = iterator.next();
+            System.out.println(student);
+        }
+
+    }
+}

src/chapter6/Example12.java

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+package chapter6;
+
+import java.util.TreeSet;
+
+public class Example12 {
+    public static void main(String[] args) {
+        Student s1 = new Student("1", "张三");
+        s1.setHeight(175);
+        Student s2 = new Student("2", "李四");
+        s2.setHeight(170);
+        Student s4 = new Student("3", "王五");
+        s4.setHeight(180);
+
+        TreeSet<Student> students = new TreeSet<>();
+        students.add(s1);
+        students.add(s2);
+        students.add(s4);
+
+        System.out.println(students);
+    }
+}

src/chapter6/Example14.java

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+package chapter6;
+
+public class Example14 {
+}

src/chapter6/Example15.java

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+package chapter6;
+
+public class Example15 {
+}

src/chapter6/Example19.java

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+package chapter6;
+
+public class Example19 {
+}

src/chapter6/Example21.java

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+package chapter6;
+
+public class Example21 {
+}

src/chapter6/Example22.java

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+package chapter6;
+
+public class Example22 {
+}

src/chapter6/Example23.java

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+package chapter6;
+
+public class Example23 {
+}

src/chapter6/Example24.java

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+package chapter6;
+
+public class Example24 {
+}

src/chapter6/Example25.java

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+package chapter6;
+
+public class Example25 {
+}