Question

I want to count the spaces in a string:

public class SongApp {
    public static void main(String[] args) {
        String word = "a b c";

        int i =0,spaceCount=0;

        while(i<word.length()){

            char temp = word.charAt(i);         
            System.out.println(temp);
            if(" ".equals(temp)){
                spaceCount++;
            }
            i++;            
        }
        System.out.println("Spaces in string: "+spaceCount);
    }
}

When I replace the if statement with if(temp.equals(" ")), I get a “cannot invoke(String) on the primitive type char.

I don’t understand why this won’t work.

Answer 1

It won’t work because you are calling a method of Class String (equals()) on a value which is of primitive type ‘char’. You are trying to compare a ‘char’ with a ‘String’.

You must compare between ‘char’s and since it’s a primitive value you need to use ‘==’ boolean compare operator like:

public class SongApp {

    public static void main(String[] args) {

      String word = "a b c";
      int i = 0,
      spaceCount = 0;

      while( i < word.length() ){
        if( word.charAt(i) == ' ' ) {
            spaceCount++;
        }
        i++;
      }

      System.out.println("Spaces in string: "+spaceCount);
    }
}