StringCutter

package main;

import java.util.ArrayList;
import java.util.Arrays;

/**
* EM RESPOSTA A http://respostas.guj.com.br/52035-quebrar-string-de-4-em-4-caracteres
*/
public class StringCutter {

    public static String[] cutted(String source, int power){
        //System.out.println("Cortando a String \"" + source + "\" em " + power + " em " + power + " unidade(s)...");

        System.out.println(new StringBuilder("Cortando a String \"").append(source).append("\" em ").append(power).append(" em ").append(power).append(" unidade(s)...").toString());

        ArrayList<String> listaAuxiliar = new ArrayList<>();

        for (int i = 0; i < source.length(); i += power){
            try {
                StringBuilder x = new StringBuilder();
                x.append(source.substring(i, i+power));
                listaAuxiliar.add(x.toString());
            }
            catch (ArrayIndexOutOfBoundsException | StringIndexOutOfBoundsException e){

                StringBuilder y = new StringBuilder();
                for (int j = i; j < source.length(); j++){
                    y.append(source.charAt(j));
                }
                listaAuxiliar.add(y.toString());
            }
        }

        System.out.println("O resultado é:");
        return listaAuxiliar.toArray(new String[listaAuxiliar.size()]);
    }

    public static void main(String[] args) {
        //ALGUNS TESTES...

        System.out.println(Arrays.toString(cutted("1234", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("12345", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("123456", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("12345678", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("123456789", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("123", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("1", 4)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("123", 3)));
        System.out.println();

        System.out.println(Arrays.toString(cutted("1234", 3)));
        System.out.println();

        System.out.println(Arrays.toString(cutted(".", Integer.MAX_VALUE)));
        System.out.println();
    }
}