String.replace result is ignored?

Question

So i'm using IntelliJ and the replace buzzword is highlighted. Most of the tips are over my head so i ignore them, but what i got for this one was that the result of string.replace is ignored. Why?

would i need something like ( string = string.replace(string.charAt(i));)?

import java.util.Scanner;

public class PhoneNumberDecipher {
    public static String phoneNumber;
    public static String Decipher(String string) {
        string = phoneNumber;
        for(int i =0; i<=phoneNumber.length(); i++) {
            if(string.equalsIgnoreCase("A")
               ||string.equalsIgnoreCase("B")
               ||string.equalsIgnoreCase("C")) {
                string.replace(string.charAt(i),'2')
            }
            else if(string.equalsIgnoreCase("D")
                    ||string.equalsIgnoreCase("E")
                    ||string.equalsIgnoreCase("F")) {
                string.replace(string.charAt(i),'3');
            }
            else if(string.equalsIgnoreCase("G")
                    ||string.equalsIgnoreCase("H")
                    ||string.equalsIgnoreCase("I")) {
                string.replace(string.charAt(i),'4');
            }
            else if(string.equalsIgnoreCase("J")
                    ||string.equalsIgnoreCase("K")
                    ||string.equalsIgnoreCase("L")) {
                string.replace(string.charAt(i),'5');
            }
            else if(string.equalsIgnoreCase("M")
                    ||string.equalsIgnoreCase("N")
                    ||string.equalsIgnoreCase("O")) {
                string.replace(string.charAt(i),'6');
            }
            else if(string.equalsIgnoreCase("P")
                    ||string.equalsIgnoreCase("Q")
                    ||string.equalsIgnoreCase("R")
                    || string.equalsIgnoreCase("S")) {
                string.replace(string.charAt(i),'7');
            }
            else if(string.equalsIgnoreCase("T")
                    ||string.equalsIgnoreCase("U")
                    ||string.equalsIgnoreCase("V")) {
                string.replace(string.charAt(i),'8');
            }
            else if(string.equalsIgnoreCase("W")
                    ||string.equalsIgnoreCase("X")
                    ||string.equalsIgnoreCase("Y")
                    ||string.equalsIgnoreCase("Z")) {
                string.replace(string.charAt(i),'9');
            }
        }

        return string;
    }

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.println("Please Enter a Phone Number you Wish to Decipher...");
        phoneNumber = input.nextLine();

        System.out.print(Decipher(phoneNumber));
    }
}

score 7 · Answer 1 · edited Jun 20 '20 at 09:12

7

String objects are immutable.

From the docs:

public String replace(char oldChar,char newChar)

Returns a string resulting from replacing all occurrences of oldChar in this string with newChar.

Hope this helps.

edited Jun 20 '20 at 09:12

Community

1
1

answered Mar 16 '16 at 00:35

Imposter

253
1
10

score 4 · Answer 2 · answered Mar 16 '16 at 00:43

IntelliJ is complaining that you're calling a method whose only effect is to return a value (String.replace) but you're ignoring that value. The program isn't doing anything at the moment because you're throwing away all the work it does.

You need to use the return value.

There are other bugs in there too. You might be able to progress a little further if you use some of this code:

StringBuilder convertedPhoneNumber = new StringBuilder();
// Your loop begins here
char curCharacter = phoneNumber.charAt(i);
if (curCharacter == 'a') {
  convertedPhoneNumber.append("2");
}
// More conditional logic and rest of loop goes here.

return convertedPhoneNumber.toString();

score 3 · Answer 3 · edited Jul 13 '19 at 16:24

3

I had the same problem, but i did it like this:

String newWord = oldWord.replace(oldChar,newChar);

edited Jul 13 '19 at 16:24

Watercayman

7,970
10
31
49

answered Jul 13 '19 at 15:55

Israel Galvan

31
1

score 2 · Answer 4 · edited Jan 21 '19 at 07:58

2

use that statement string = string.replace(string.charAt(i));

Why? String is an immutable object. Look at this thread to get a complete explanation. This a fundemental part of Java, so make sure you learn it well.

edited Jan 21 '19 at 07:58

Gergely Bacso

14,243
2
44
64

answered Jan 21 '19 at 03:17

icgoogo

401
5
7

score 0 · Answer 5 · edited Dec 15 '21 at 07:45

0

string = string.replace(string.charAt(i), '<The char to replace>') will work.

Refer to this article you might understand better: https://alvinalexander.com/blog/post/java/faq-why-isnt-replace-replaceall-replacefirst-not-working/

Since string is immutable, you have to reassign the a string with the string.replace() string.

edited Dec 15 '21 at 07:45

Procrastinator

2,526
30
27
36

answered Dec 15 '21 at 07:14

Vanessa Wong

1
1

String.replace result is ignored?

5 Answers5

Linked

Related