添加:
刪除:
修改/替換:
查詢:
判斷:
求長:
<一> 添加+遍歷( keySet+get )
package kyleeo.util01;
import java.util.HashMap;
public class HushMapDemo {
public static void main(String[] args) {
HashMap<String,String> map = new HashMap<String,String>();
map.put("111","AAA");
map.put("222","bbb");
map.put("333","AAA");
for(String i:map.keySet()) {
System.out.println(i+":"+map.get(i));
}
}
}
<二> 刪除( remove )
System.out.println(map.remove("777")); //null
System.out.println(map.remove("333")); //CCC
<三> 替換
System.out.println(map.replace("111","AAAA")); //AAA(舊值)
System.out.println(map.replace("999","AAAA")); //null
System.out.println(map.replace("111", "AAAA", "AAAAA")); //true
System.out.println(map.replace("111", "XXX", "AAAAA")); //false
<四> 統計字符串中各個字符出現的次數
package kyleeo.util01;
import java.util.HashMap;
import java.util.Scanner;
public class HashMapTest {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String s = sc.nextLine();
char[] chs = s.toCharArray();
HashMap<Character,Integer> map = new HashMap<Character,Integer>();
for(Character c:chs) {
Integer i = map.get(c);
if(map.get(c)==null) {
map.put(c,1);
}else {
i++;
map.put(c,i);
}
}
for(Character c:map.keySet()) {
System.out.println(c+":"+map.get(c));
}
sc.close();
}
}