How do you mirror the lines on the horizontal axis of symmetry in the body?

[juvenalb]

There's nothing on the Internet, I want to know how to do it. Here's the program with the body itself.

class з4 {
  public static void main (String[] args){
    int[][] a=new int[4][5];
    for (int i=0;i < a.length;i++){
      for (int j=0;j < a[i].length;j++){
        a[i][j]=(int)(Math.random()*10);
      }
    }
    for (int i=0;i < a.length;i++,System.out.println()){
      for (int j=0;j < a[i].length;j++){
        System.out.print(a[i][j]+" ");
      }
    }
  }
}

[Pearlaqua]

Best:

for (int i = 0; i < a.length / 2; ++i)
{
    int tmp[] = a[i];
    a[i] = a[a.length - i - 1];
    a[a.length - i - 1] = tmp;
}

Well, if you want to be harder or you have to save your memory, you can say,

for (int i = 0; i < a.length; ++i)
    for (int j = 0; j < a[i].length; ++j)
    {
         int tmp = a[i][j];
         a[i][j] = a[a.length - i - 1][j];
         a[a.length - i - 1][j] = tmp;
    }

P.S. Actually, I'm not sure the second option would be to save memory. The first version of the compiler could simply re-examine the references.

Update

TC, I'm good tonight. I'll forgive the community... Hold the code:

class Test4 
{
    public static void main (String[] args)
    {
        // Инициализация матрицы.
        int[][] a = new int[4][5];
        for (int i = 0; i < a.length; i++)
           for (int j=0; j < a[i].length; j++)
            a[i][j] = (int)(Math.random()*10);
    // Вывод исходной матрицы
    for (int i=0;i &lt; a.length;i++,System.out.println())
      for (int j=0;j &lt; a[i].length;j++)
        System.out.print(a[i][j]+" ");

    // Трансформация матрицы.
    for (int i = 0; i &lt; a.length / 2; ++i) {
        int tmp[] = a[i];
        a[i] = a[a.length - i - 1];
        a[a.length - i - 1] = tmp;
    }

    // Вывод изменённой матрицы.
    System.out.println();
    for (int i=0;i &lt; a.length;i++,System.out.println())
      for (int j=0;j &lt; a[i].length;j++)
        System.out.print(a[i][j]+" ");
}

}