java - 需要有关我的程序在 String 中查找重复项的效率的输入

Question

我开发了一个 java 程序来检查字符串是否具有所有唯一字符。我列出来了。如果我得到有关该程序效率的输入以及改进该程序所需的任何更正，我将不胜感激。提前致谢。

package com.string.duplicatechars;

import java.util.HashMap;
import java.util.Map;

public class CheckForDuplicateChars {

        /**
         * @param args
         */
        public static void main(String[] args) {
                String sampleString = "abcdabxyz";
                boolean allUniqueCharacters = allUniqueCharacters(sampleString);
                System.out.println("Are all characters unique: "+allUniqueCharacters);
        }

        public static boolean allUniqueCharacters(String sampleString) {
                boolean allUniquCharacters = true;
                char[] charArrForString = sampleString.toCharArray();
                Map<Character, Boolean> resultHashMap = new HashMap<Character, Boolean>();

                for(char ch: charArrForString){
                        Boolean isAlreadyPresent = (Boolean)resultHashMap.put(new Character(ch), new Boolean(true));

                        if(isAlreadyPresent != null){
                                if(isAlreadyPresent.booleanValue() == true) {
                                        System.out.println("Got repeated character: "+ch);
                                        allUniquCharacters = false;
                                }
                        } else {
                                System.out.println("Character "+ch+ " is being iserted first time");
                        }
                }

                return allUniquCharacters;
        }
}

Answer 1

我会使用 Set<Character> 反而。当您尝试 add 一个字符到集合中，它将返回 false如果集合已经包含那个字符。

for(char c: yourCharArray){
    if(!set.add(c)){
        return false;
    }
}