黑马程序员——集合框架类总结

 1 练习
 2 package blogtest2;
 3 import java.util.*;
 4 public class ArrayListTest {
 5 
 6  /**
 7   * 将自定义对象传入到ArrayList集合中，并去除重复元素
 8   */
 9  public static void main(String[] args) {
10   ArrayList<People> arraylist = new ArrayList<People>();
11   arraylist.add(new People("zhangshan",22));
12   arraylist.add(new People("lishan",24));
13   arraylist.add(new People("wangwu",15));
14   arraylist.add(new People("zhangshan",22));
15   ArrayList<People> singlist = singleName(arraylist);
16   for(People stu : singlist){
17    System.out.println(stu);
18   }
19  }
20 
21 
22 public static ArrayList<People> singleName(ArrayList<People> arraylist){
23  ArrayList<People> list = new ArrayList<People>();
24  Iterator<People> ite = arraylist.iterator();
25  while(ite.hasNext()){
26   People stu = ite.next();
27   if(!list.contains(stu)){
28    list.add(stu);
29   }
30  }
31  return list;
32 }
33 }
34 class People{
35  private String name;
36  private int age;
37  People(String name,int age){
38   this.name = name;
39   this.age = age;
40  }
41  public String getName(){
42   return name;
43  }
44  public int getAge(){
45   return age;
46  }
47  public String toString(){
48   return name +"...."+age;
49  }
50  public boolean equals(Object stu){
51   if(!(stu instanceof People)){
52    return false;
53   }
54   People stucopy = (People)stu;
55   return this.name.equals(stucopy.name) && this.age == stucopy.age;
56  }
57 }

 1 练习
 2 package blogtest2;
 3 import java.util.*;
 4 public class LinkedListTest {
 5 
 6  /**
 7   * 用LinkedList模拟堆栈或者队列结构
 8   */
 9  public static void main(String[] args) {
10   LinkedList<String> linkedlist = new LinkedList<String>();
11   linkedlist.addFirst("java1");
12   linkedlist.addFirst("java2");
13   linkedlist.addFirst("java3");
14   linkedlist.addFirst("java4");
15   System.out.println(linkedlist);
16  
17   LinkedList<String> linkedlist2 = new LinkedList<String>();
18   linkedlist2.addLast("java1");
19   linkedlist2.addLast("java2");
20   linkedlist2.addLast("java3");
21   linkedlist2.addLast("java4");
22   System.out.println(linkedlist2);
23  
24    
25  }
26 
27 }

 1 练习
 2 package blogtest2;
 3 import java.util.HashSet;
 4 public class HashSetTest {
 5 
 6  /**
 7   * 将自定义对象存入HashSet中，同姓名和年龄为重复元素
 8   */
 9  public static void main(String[] args) {
10   HashSet<Student> hashset = new HashSet<Student>();
11   hashset.add(new Student("zhangshan",22));
12   hashset.add(new Student("lishan",24));
13   hashset.add(new Student("wangwu",15));
14   hashset.add(new Student("zhangshan",22));
15   for(Student stu : hashset){
16    System.out.println(stu);
17   }
18 
19  }
20 
21 }
22 class Student implements Comparable<Student>{
23  private String name;
24  private int age;
25  Student(String name,int age){
26   this.name = name;
27   this.age = age;
28  }
29  public String getName(){
30   return name;
31  }
32  public int getAge(){
33   return age;
34  }
35  public String toString(){
36   return name +"...."+age;
37  }
38  public int hashCode(){
39   return this.name.hashCode() + this.age * 30;
40  }
41  public boolean equals(Object stu){
42   if(!(stu instanceof Student)){
43    return false;
44   }
45   Student stucopy = (Student)stu;
46   return this.name.equals(stucopy.name) && this.age == stucopy.age;
47  }
48  public int compareTo(Student stu){
49   int num = new Integer(this.age).compareTo(new Integer(stu.age ));
50   if(num == 0){
51    return this.name.compareTo(stu.name);
52   }
53   return num;
54  }
55 }

 1 练习
 2 package blogtest2;
 3 import java.util.*;
 4 public class TreeSetTest {
 5 
 6  /**
 7   * 往TreeSet中存入自定义对象学生，按学生的年龄排序
 8   */
 9  public static void main(String[] args) {
10   // TODO Auto-generated method stub
11   TreeSet<Student> treeset = new TreeSet<Student>(new MyComparator());
12   treeset.add(new Student("zhangshan",22));
13   treeset.add(new Student("lishan",24));
14   treeset.add(new Student("wangwu",15));
15   treeset.add(new Student("zhangshan",22));
16   for(Student stu : treeset){
17    System.out.println(stu);
18   }
19 
20  }
21 }
22 class MyComparator implements Comparator<Student>{
23  public int compare(Student stu1,Student stu2){
24   int num = stu1.getName().compareTo(stu2.getName());
25   if(num == 0){
26    return new Integer(stu1.getAge()).compareTo(new Integer(stu2.getAge()));
27   }
28   return num;
29  }
30 }
31 class Student implements Comparable<Student>{
32  private String name;
33  private int age;
34  Student(String name,int age){
35   this.name = name;
36   this.age = age;
37  }
38  public String getName(){
39   return name;
40  }
41  public int getAge(){
42   return age;
43  }
44  public String toString(){
45   return name +"...."+age;
46  }
47   Student stucopy = (Student)stu;
48   return this.name.equals(stucopy.name) && this.age == stucopy.age;
49  }
50  public int compareTo(Student stu){
51   int num = new Integer(this.age).compareTo(new Integer(stu.age ));
52   if(num == 0){
53    return this.name.compareTo(stu.name);
54   }
55   return num;
56  }
57 }

 1 练习
 2 package blogtest2;
 3 import java.util.*;
 4 public class HashMapTest {
 5  /**
 6   *演示Map集合两种取出方式
 7   */
 8  public static void main(String[] args) {
 9   Map<String,String> map = new HashMap<String,String>();
10   map.put("zhangshan", "22");
11   map.put("lisi", "33");
12   map.put("wangwu", "44");
13   map.put("xiaoming", "55");
14   //第一种取出方式
15   Set<Map.Entry<String, String>> set = map.entrySet();
16   Iterator<Map.Entry<String, String>> ite = set.iterator();
17   while(ite.hasNext()){
18    Map.Entry<String, String> mapentry = ite.next();
19    String key = mapentry.getKey();
20    String value = mapentry.getValue();
21    System.out.println(key + "=" + value);
22   }
23   //第二种取出方式
24   Set<String> set2 = map.keySet();
25   Iterator<String> ite2 = set2.iterator();
26   while(ite2.hasNext()){
27    String key2 = ite2.next();
28    String value2 = map.get(key2);
29    System.out.println(key2 + "=" + value2);
30   }
31  }
32 }