Checking to see if a string is letters + spaces ONLY?

Question

I want to write a static method that is passed a string and that checks to see if the string is made up of just letters and spaces. I can use String's methods length() and charAt(i) as needed..

I was thinking something like the following: (Sorry about the pseudocode)

public static boolean onlyLettersSpaces(String s){
for(i=0;i<s.length();i++){
if (s.charAt(i) != a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z) {
return false;
break;
}else {
return true;
}
}

I know there is probably an error in my coding, and there is probably a much easier way to do it, but please let me know your suggestions!

Solution 1

use a regex. This one only matches if it starts with, contains, and ends with only letters and spaces.

^[ A-Za-z]+$

In Java, initialize this as a pattern and check if it matches your strings.

Pattern p = Pattern.compile("^[ A-Za-z]+$");
Matcher m = p.matcher("aaaaab");
boolean b = m.matches();

Solution 2

That isn't how you test character equality, one easy fix would be

public static boolean onlyLettersSpaces(String s){
  for(i=0;i<s.length();i++){
    char ch = s.charAt(i);
    if (Character.isLetter(ch) || ch == ' ') {
      continue;
    }
    return false;
  }
  return true;
}

Comments

[user3735218]

What is "ch"?*******************

[Elliott Frisch]

@user3735218 Sorry, edited. That was a copy paste error. char ch = s.charAt(i);

[user3735218]

If I put a return statement inside a loop, will the loop cancel? Hoping it does

[Durandal]

@user3735218 Yes it will. Try to solve it in real code, you will see that a return followed by break gives a compiler error, since the return makes it impossible to ever reach the break.

[Durandal]

Character.isLetter() returns true for much more than just A-z. Its probably not what the OP needs (I suspect it to be a homework assignment and that the task is to solve both the character ok/bad decision as well as the string loop logic).