got it to work somehow

Java Code:
public class ASDFSA {
	public static void main(String args[]) {
		System.out.print(isInteger("09031"));
	}
	
	
	public static boolean isInteger(String source) {
		
		char c;
		for (int x = 0; x < source.length(); x++) {
			c = source.charAt(x);
			if (c < '0' || c > '9') {
				return false;
			
			}
		}
			
		int length = source.length();
		if (length == 0) {
			return false;
		} else {
			return true;
		}
		
		
		
				
				
				
				
				
	

		
		
	}


}
thanks a lot