CODEWITHSUNDEEP
java
junxi
junxi

Reputation: 174

How to change a char in a String - replacing letters java

Simular topics were not able to solve my problem. I need to change the char 'a' to 'x' in an given String str.

Example: "abc" = "xbc". I am only allowed to use substring(), charAt() - no replace() method.

My code so far:

public static String ersetze(String text){
    for(int i = 0; i<text.length(); i++){

        if(text.substring(i, i+1).charAt(i) == 'a'){
            text.substring(i, i+1) = 'x'; 
        }
    }
    //return statement
}

Now the error is text.substring(i, i+1) = 'x';that the left assignment must be a variable - clear. But how to assigne the letter to a variable now? If I declare a char x; how to put that x in the String to replace the letter?

Upvotes: 3

Views: 9583

Answers (4)

Rakib Hasan
Rakib Hasan

Reputation: 315

String can not replace with character. First Need to create character array & then replace.

public static String ersetze(String text){
    char[] result = text.toCharArray();
    for(int i = 0; i < result.length; i++){
        if(result [i] == 'a'){
            result[i] = 'x';
        }
    }
    return String.valueOf(result);
}

Upvotes: 5

Alberto Trindade Tavares
Alberto Trindade Tavares

Reputation: 10356

String is immutable in Java, so you cannot replace a letter of a String. You need to create a new String.

You can convert the String to an array of chars and changing only the needed ones, then create a new String from this array:

public static String ersetze(String text){
    char[] letters = text.toCharArray();

    for (int i = 0; i < letters.length; i++){
        if (letters[i] == 'a') {
            letters[i] = 'x';
        }
    }

    return new String(letters);
}

Upvotes: 5

P.An
P.An

Reputation: 353

If you REALLLLLY need this and you are limited to the methods you mentioned then you can do this each time you find requested char: text = text.substring(0, i) + x + text.substring(i + 1);

Upvotes: 2

ja08prat
ja08prat

Reputation: 154

Convert the string to a character array (included in the java API), iterate through the array and replace all the "a"'s with "x"'s in the char array and then change it back to a string.

Upvotes: 0

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