import java.util.Arrays;
 
class Diamante {
 
  private static final String[] ALFABETO = {"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"};
 
  public static void montar(String escolhida) {
    int maximo = Arrays.binarySearch(ALFABETO, escolhida); // Encontra a posição da letra passada como parâmetro
    boolean par = (maximo % 2) == 0; // Verifica se o número é par ou impar para cálculo da posição
    int metade = Math.floorDiv(maximo, 2); // Encontra a posição onde ficará o meio do diamante
    String espacos = "               ".substring(0, metade); //Corta o número de espaços para realizar o espelhamento
    int posicao = 0; // Inicia o contador de posição
 
    for (int indice = 0; indice <= maximo; indice++) {
      String letra = ALFABETO[indice];
      StringBuilder construtor = new StringBuilder(espacos); // Monta um StringBuilder para substituição das letras
      String texto;
 
      // Se for a primeira posição ou a última não espelha o texto
      if (posicao == 0) {
        texto = espacos + letra + espacos;
      } else {
        construtor.setCharAt(posicao - 1, letra.charAt(0)); // Coloca a letra na posição correta dentro da String de espaços
        texto = construtor.toString();
        texto = inverter(texto) + " " + texto; // Inverte o texto obtido criando espelhamento
      }
 
      System.out.println(texto); // Imprime na tela
 
      if (indice < metade) { // Caso ainda não tenha passado da metade, coloca mais espaços
        posicao++;
      } else if (par || indice > metade) { // Caso tenha passado da metade ou seja par e esteja na metade começa a remover espaços
        posicao--;
      }
    }
  }
 
  public static String inverter(String texto) {
    StringBuilder construtor = new StringBuilder(texto);
 
    return construtor.reverse().toString();
  }
 
  public static void main(String[] args) {
    montar("H");
  }
}
 

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