[RESOLVIDO] Combinações

public static void main(String[] args) {

    	final String COMPLEMENTO = "ABCDEFGHIJ";
    	
        String sInput = JOptionPane.showInputDialog("Digite uma palavra", null);
        String sInputTratado = (sInput==null? "": sInput).toUpperCase().concat(COMPLEMENTO).substring(0, 10); 
        
        char arrayChar[] = sInputTratado.toCharArray();
        char par[] = new char[2];

        for (char charPrincipal: arrayChar) {
        	par[0] = charPrincipal;
            for (char charCombinado: arrayChar) {
            	par[1] = charCombinado;
            	System.out.format("%c%c", par[0], par[1]);
            }
        	System.out.print("\n");
        }

   }

package extras01;

import javax.swing.JOptionPane;

public class Ex12_string {

    public static void main(String[] args) {
        String vet[] = {"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"};
        String palavra = JOptionPane.showInputDialog(null, "Digite uma palavra "), combinacoes = "";
        int cont = 0;

        while (palavra.length() < 10) {
            palavra = palavra.concat(vet[cont]).toUpperCase();
            cont++;
        }
        if (palavra.length() > 10) {
            palavra = palavra.substring(0, 10).toUpperCase();
        }

        cont = 0;
        char arrayCaracter[] = palavra.toCharArray();

        while (palavra.length() > cont) {
            for (int i = 0; i < palavra.length(); i++) {
                combinacoes += Character.toString(palavra.charAt(cont)) + (Character.toString(arrayCaracter[i])) + "\n";
            }
            cont++;
        }
        System.out.printf("%s", combinacoes);
    }
}