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Revolucion for Monica
Asked: 2020-05-01 06:37:15 +0800 CST 2020-05-01 06:37:15 +0800 CST

Can't change a character with .charAt()?

  • 772

I want to make a java program to replace spaces with % 20. I was thinking of making a loop and when I find a " "replacement the character with the three characters. However I have a problem with .charAt(). Indeed it seems that you can not change a character. Here is the error:

replaceSpaces.java:8: error: unexpected type
                s.charAt(i)="%20";
                        ^
  required: variable
  found:    value

Here is the entire program:

public class replaceSpaces{
    String s = "Hello Antoine";
    public static void replaceSpaces(String s){
        for(int i = 0;i<s.length();i++){
            if(s.charAt(i)==' '){
                s.charAt(i)="%20";
            }
        }
    System.out.println(s);
    }
}
java

3 Answers

  1. Best Answer

    string.charAtreturns a new instance of the character that is in the indicated position so you can't edit that character in the string.

    Try using the method string.replace()to replace all characters equal to the first parameter:

    public static void replaceSpaces(String s){
       s = s.replace(" ", "%20");
       System.out.println(s);
}
replaceSpaces("Hello Antoine"); // imprime Hello%20Antoine

    Note that it Stringis immutable so it will always return a new instance, so you will have to return the result instead of assigning it to the variable sif you want to get the string with the spaces replaced:

     public static string replaceSpaces(String s){
     return s.replace(" ", "%20");
 }
 String texto = replaceSpaces("Hello Antonie");
 System.out.println(texto);// Hello%20Antonie
    • 10

  2. You should do it with the method of the String object:

    replaceAll("a", "b")

    In this case it replaces the matches of "a" with "b".

    In your case it would be:

    public static void replaceSpaces(String s){
    String s = "Hello Antoine";
    String res = ""; 
    res = s.replaceAll(" ", "%20"); // remplaza espacios por %20
    System.out.println(res); // "Hello%20Antoine"
}
    • 2

  3. The method you are looking for is replace, which searches a string for the letter and replaces it with another. Your code would look like this:

    String s = "Hello Antoine";
System.out.println(s);
//Primer parámetro letra a buscar y segundo parámetro letra a reemplazar
String replace = s.replaceAll(" ", "%20");
System.out.println(replace);

    Departure:

    Hello Antoine
Hello%20Antoine

    For more information the official documentation here:

    https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replaceAll(java.lang.String,%20java.lang.String)

    • 2