Map 統計字元串中每個字元出現次數
package com.code.ggsddu;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class CharacterNumberByMap {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Input your string: ");
String str = scanner.nextLine();
Map<Object, Object> map = calculate(str);
for (Object key : map.keySet()) {
System.out.println("key: " + key + ", value: " + map.get(key));
}
}
/**
* 1.containsKey 判斷 map 中是否存在該字元
* 2.若不存在,則設該字元出現次數為 1,并将該字元(K)、重複次數(V) put 到 map
* 3.若字元已存在,獲得該字元出現次數,加 1, 并重新 put 到 map,覆寫更新
*/
public static Map<Object, Object> calculate(String str) {
char[] charArr = str.toCharArray();
Map<Object, Object> map = new HashMap<>();
for (int i = ; i < charArr.length; i++) {
if (!map.containsKey(charArr[i])) {
map.put(charArr[i], );
} else {
int counts = (int) map.get(charArr[i]) + ;
map.put(charArr[i], counts);
}
}
return map;
}
}
控制台列印結果:
Input your string: java
key: a, value:
key: v, value:
key: j, value:
Process finished with exit code