Set-TreeSet-Comparable and treeset

Set-TreeSet-Comparable and treeset

Student Class: name and age attributes
1 package com. bjpowernode. test01_set2_Comparable; 2/* 3 * T: type 4 */5 public class Student implements Comparable <Student> {6 private String name; 7 private int age; 8 public String getName () {9 return name; 10} 11 public void setName (String name) {12 this. name = name; 13} 14 public int getAge () {15 return age; 16} 17 public void setAge (int age) {18 this. age = age; 19} 20 public Student (String nam E, int age) {21 super (); 22 this. name = name; 23 this. age = age; 24} 25 public Student () {26 super (); 27 // TODO Auto-generated constructor stub28} 29/* @ Override30 public int hashCode () {31 final int prime = 31; 32 int result = 1; 33 result = prime * result + age; 34 result = prime * result + (name = null )? 0: name. hashCode (); 35 return result; 36} 37 @ Override38 public boolean equals (Object obj) {39 if (this = obj) 40 return true; 41 if (obj = null) 42 return false; 43 if (getClass ()! = Obj. getClass () // determines whether the types of the two "objects" are the same. 44 return false; 45 Student other = (Student) obj; // perform a downward transformation of 46 if (age! = Other. age) 47 return false; 48 if (name = null) {// avoid NullPointerException exception 49 if (other. name! = Null) 50 return false; 51} else if (! Name. equals (other. name) 52 return false; 53 return true; 54} */55/* 56 * when the current object and the parameter object are both returned: 057 * when the current object is greater than the parameter object: 1 positive 58 * when the current object is smaller than the parameter object:-1 negative 59 */60 @ Override61 public int compareTo (Student s) {62 // sort by age. if the age is the same, sort by name 63 if (this. age = s. age) {64 // sort by name, call compareTo65 return this of the string. name. compareTo (s. name); 66} 67 return this. age-s. age; 68}69 70}

TreeSet storage, traversal, and sorting output
1 package com. bjpowernode. test01_set2_Comparable; 2 3 import java. util. treeSet; 4/* 5 * elements stored in TreeSet. By default, repeated items are removed in the natural sorting mode, and the natural sorting method is specified in the 6 * String and 8 packaging classes in the sorting mode: java. lang. comparable interface, rewrite the compareTo Method 7 * When the custom class is put into the TreeSet, java is also implemented. lang. comparable interface, override compareTo Method 8 */9 public class StudentTreeSetTest {10 public static void main (String [] args) {11 TreeSet <Student> tree = new TreeSet <> (); 12 Student s = new Student ("Mike", 18); 13 Student s1 = new Student ("Join", 28); 14 Student s3 = new Student ("Join ", 18); 15 Student s4 = new Student ("Smith", 18); 16 tree. add (s); 17 tree. add (s1); 18 tree. add (s3); 19 tree. add (s4); 20 System. out. println (tree. size (); 21 System. out. println ("Name \ t age"); 22 for (Student stu: tree) {23 System. out. println (stu. getName () + "\ t" + stu. getAge (); 24} 25} 26}