该程序将找出String中的重复字符并显示它们的计数。
import java.util.HashMap;import java.util.Map;import java.util.Set;public class Details { public void countDupChars(String str){ //Create a HashMap Map<Character, Integer> map = new HashMap<Character, Integer>(); //Convert the String to char array char[] chars = str.toCharArray(); /* logic: char are inserted as keys and their count * as values. If map contains the char already then * increase the value by 1 */ for(Character ch:chars){ if(map.containsKey(ch)){ map.put(ch, map.get(ch)+1); } else { map.put(ch, 1); } } //Obtaining set of keys Set<Character> keys = map.keySet(); /* Display count of chars if it is * greater than 1\. All duplicate chars would be * having value greater than 1. */ for(Character ch:keys){ if(map.get(ch) > 1){ System.out.println("Char "+ch+" "+map.get(ch)); } } } public static void main(String a[]){ Details obj = new Details(); System.out.println("String: BeginnersBook.com"); System.out.println("-------------------------"); obj.countDupChars("BeginnersBook.com"); System.out.println("\nString: ChaitanyaSingh"); System.out.println("-------------------------"); obj.countDupChars("ChaitanyaSingh"); System.out.println("\nString: #@[email protected]!#%!!%@"); System.out.println("-------------------------"); obj.countDupChars("#@[email protected]!#%!!%@"); }}
输出：
String: BeginnersBook.com-------------------------Char e 2Char B 2Char n 2Char o 3String: ChaitanyaSingh-------------------------Char a 3Char n 2Char h 2Char i 2String: #@[email protected]!#%!!%@-------------------------Char # 2Char ! 3Char @ 3Char 2Char % 2 
