Validator for Inputs from User

Valid.java

import java.util.ArrayList;
import java.util.Vector;
public class Valid {
	/*
	 * This user-defined class is made by James Carlo Luchavez.
	 * This class is composed of the following Data Validating Methods:
	 * (a) "isDuplicate" returns the index of the given data from the array - Vector, ArrayList, Normal Array
	 * (b) "removeExcessSpace" returns a lowercase string with only one space from each word or element
	 * (c) "firstLetterUp" returns a string with first letters of each word capitalized (for names)
	 * (d) "toInteger" converts a string value to integer
	 * (e) "toDouble" converts a string value to double
	 * (f) ""
	 */
	
	//	Vector Array isDuplicate
	static int isDuplicate(String s, Vector<String> arr) { // String Array
		for(String x: arr) {
			if(x.equalsIgnoreCase(s)) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(int s, Vector<Integer> arr) { // Integer Array
		for(int x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(double s, Vector<Double> arr) { // Double Array
		for(double x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(char s, Vector<Character> arr) { // Character Array
		for(char x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	//	ArrayList isDuplicate
	static int isDuplicate(String s, ArrayList<String> arr) { // String Array
		for(String x: arr) {
			if(x.equalsIgnoreCase(s)) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(int s, ArrayList<Integer> arr) { // Integer Array
		for(int x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(double s, ArrayList<Double> arr) { // Double Array
		for(double x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	static int isDuplicate(char s, ArrayList<Character> arr) { // Character Array
		for(char x: arr) {
			if(x == s) {
				return arr.indexOf(s);
			}
		}
		return -1;
	}
	//	Normal Array isDuplicate
	static int isDuplicate(String s, String arr[]) { // String Array
		for (int i = 0; i < arr.length; i++) {
			if(arr[i].equals(s))
				return i;
		}
		return -1;
	}
	static int isDuplicate(int s, int arr[]) { // Integer Array
		for (int i = 0; i < arr.length; i++) {
			if(arr[i] == s)
				return i;
		}
		return -1;
	}
	static int isDuplicate(double s, double arr[]) { // Double Array
		for (int i = 0; i < arr.length; i++) {
			if(arr[i] == s)
				return i;
		}
		return -1;
	}
	static int isDuplicate(char s, char arr[]) { // Character Array
		for (int i = 0; i < arr.length; i++) {
			if(arr[i] == s)
				return i;
		}
		return -1;
	}
	
	//	Excess Whitespace Remover
	static String removeExcessSpace(String s){
		if(s.equals("")) return s;
		if(allSpace(s)) return "";
		String hold = "";
		char c;
		for (int i = 0; i < s.length(); i++) { // REMOVES INAPPROPRIATE WHITESPACES
			c = s.charAt(i);
			if(Character.isLetter(c)) {
				hold+=c;
			}
			else if(Character.isWhitespace(c) && hold.length() > 0 && !Character.isWhitespace(hold.charAt(hold.length()-1))) {
				hold+=" ";
			}
		}
		return hold;
	}
	
	//	First Letter to Uppercase
	static String firstLetterUp(String s) {
		s = removeExcessSpace(s);
		if(s.equals("")) return s;
		String hold = "";
		String[] arr = s.split(" ");
		for (int i = 0; i < arr.length; i++) { // CONVERTS FIRST LETTER FOR EACH WORD
			arr[i] = arr[i].toUpperCase().charAt(0)+arr[i].toLowerCase().substring(1);
			hold+=arr[i];
			if(i != arr.length-1) {
				hold+=" ";
			}
		}
		return hold;
	}
	
	//	String to Integer
	static int toInteger(String s) {
		if(s == null) return -1;
		String hold = "";
		char c;
		for(int i = 0; i < s.length(); i++) {
			c = s.charAt(i);
			if(Character.isDigit(c)) {
				hold+=c;
			}
			if(c == '-' && hold.equals("")){
				hold+=c;
			}
		}
		if(hold.equals("")) return 0;
		else return Integer.parseInt(hold);
	}
  
  	//	String to Double
	static Double toDouble(String s) {
		if(s == null) return (double) -1;
		String hold = "";
		int ctr = 0;
		char c;
		for(int i = 0; i < s.length(); i++) {
			c = s.charAt(i);
			if(Character.isDigit(c)) {
				hold+=c;
			}
			else if(c == '-' && hold.equals("")) {
				hold+=c;
			}
			else if(c == '.' && ctr != 1) {
				hold+=c;
				ctr++;
			}
		}
		if(hold.equals("")) return 0.0;
		else return Double.parseDouble(hold);
	}
  
  	//	Checks if a string contains only whitespaces
	static boolean allSpace(String s) {
		if(s == null) return true;
		char c;
		for(int i = 0; i < s.length(); i++) {
			c = s.charAt(i);
			if(!Character.isWhitespace(c)) {
				return false;
			}
		}
		return true;
	}
}