sample java interview question

ReverseWordCharsInSentence.java

package com.learning;

import java.util.Arrays;
import java.util.stream.Collectors;

/**
 * Created by sargonbenjamin on 5/3/20.
 */
public class ReverseWordCharsInSentence {

    public static void main(String args[]){
        System.out.println(solveProblem("Hi my name is ABCD"));
        System.out.println(solveProblemByStreams("Hi my name is ABCD"));
    }

    public static String solveProblem(String input){
        if(input == null || input.isEmpty())return input;

        //split or java StringTokenizer is fine
        String[] tokens = input.split(" ");
        StringBuilder sb = new StringBuilder("");
        for(String str : tokens){
            sb.append(reverseString(str) + " ");
        }
        //remove the last space character
        return sb.substring(0,sb.length()-1);
    }

    public static String solveProblemByStreams(String input){
        return Arrays.stream(input.split(" "))
            .map(ReverseWordCharsInSentence::reverseString)
            .collect( Collectors.joining(" ") );
    }

    /**
     * reverse string by only looping through half the characters
     * this optimization is not necessary
     * @param input
     * @return
     */
    public static String reverseString(String input){
        if(input == null || input.isEmpty()) return input;

        char[] charArr = input.toCharArray();
        for(int i = 0; i<charArr.length/2; i++){
            char temp = charArr[i];
            charArr[i] = charArr[charArr.length-1-i];
            charArr[charArr.length-1-i] = temp;
        }

        return new String(charArr);
    }

}