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JAVA基础知识之JVM-——集合练习
1.创建一个Set集合,保存用户输入的数据
1 package test; 2 3 import java.io.BufferedReader; 4 import java.io.IOException; 5 import java.io.InputStreamReader; 6 import java.util.ArrayList; 7 import java.util.HashMap; 8 import java.util.HashSet; 9 import java.util.Iterator; 10 import java.util.LinkedHashSet; 11 import java.util.List; 12 import java.util.Map; 13 import java.util.Set; 14 15 class A { 16 public int count; 17 public A(int count) { 18 this.count = count; 19 } 20 21 public boolean equals(Object obj){ 22 if (this == obj) { 23 return true; 24 } 25 if (obj != null && obj.getClass() == A.class) { 26 A r = (A)obj; 27 return r.count == this.count; 28 } 29 return false; 30 } 31 32 public int hashCode() { 33 return this.count; 34 } 35 36 public String toString() { 37 return this.count+""; 38 } 39 40 } 41 public class TestCollection { 42 public static void testSet() throws Exception { 43 //Set set = new LinkedHashSet(); 44 //Set set = new TreeSet(); 45 Set set = new HashSet(); 46 int keyIn; 47 int num = 0; 48 49 while ( num++ < 2) { 50 //Scanner sc = new Scanner(System.in); 51 //keyIn = sc.nextInt(); 52 BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 53 keyIn = Integer.parseInt(br.readLine()); 54 set.add(new A(keyIn)); 55 } 56 System.out.println(set); 57 } 58 59 public static void testList() { 60 List list = new ArrayList(); 61 for (int i=0; i<10; i++) { 62 list.add(new A(i)); 63 } 64 System.out.println(list); 65 } 66 67 public static void testMap() { 68 String[] str = new String[] {"a","b","a","b","c","a","b","c"}; 69 Map<String, Integer> map = new HashMap(); 70 Set<String> set = new LinkedHashSet(); 71 for (int i = 0; i < str.length; i++) { 72 set.add(str[i]); 73 } 74 75 76 String key; 77 Iterator it = set.iterator(); 78 while (it.hasNext()) { 79 int val = 0; 80 key = (String)it.next(); 81 for (int i = 0; i < str.length; i++) { 82 if (str[i] == key) val++; 83 } 84 map.put(key, val); 85 } 86 87 System.out.println(map); 88 } 89 90 public static void main(String[] args) throws Exception { 91 //TestCollection.testSet(); 92 //TestCollection.testList(); 93 TestCollection.testMap(); 94 } 95 }
JAVA基础知识之JVM-——集合练习
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