第六篇 集合与容器(六)
set
package com.zzp.demo; import java.util.HashSet; import java.util.Set; /** * * 测试set * @author java * */ public class TestSet { public static void main(String[] args) { Set<String> set1 = new HashSet<>(); set1.add("aa"); set1.add("bb"); set1.add("cc"); System.out.println(set1); set1.add("aa"); System.out.println(set1); Set<String> set2 = new HashSet<>(); set2.add("张三"); set2.add("李四"); set2.addAll(set1); System.out.println(set2); } }
手动实现HashSet
package com.zzp.demo.myCollection; import java.util.HashMap; /** * * 手动实现一个HashSet * @author java * */ public class HashSet01 { HashMap map; private static final Object p = new HashMap(); public HashSet01() { map = new HashMap(); } public int size(){ return map.size(); } public void add(Object o){ map.put(o, p); } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("["); for(Object key : map.keySet()){ sb.append(key +","); } sb.setCharAt(sb.length()-1, ']'); return sb.toString(); } public static void main(String[] args) { HashSet01 hashMap01 = new HashSet01(); hashMap01.add(12); hashMap01.add(13); hashMap01.add(14); System.out.println(hashMap01.size()); System.out.println(hashMap01.toString()); } }
TreeSet的使用
package com.zzp.demo; import java.util.Set; import java.util.TreeSet; /** * * 测试TreeSet的使用 * @author java * */ public class TestTreeSet { public static void main(String[] args) { Set<Integer> set = new TreeSet<>(); set.add(100); set.add(50); set.add(10); set.add(200); System.out.println(set); } }