Nested for loops exercise

// print following
// 0 1 2
// 0 1 2
// 0 1 2 
for (int a = 0; a < 3; a++) {
  for (int i = 0; i < 3; i++) {
    System.out.print(i + " ");
  } // inner of for
  System.out.println();
} // out of for

// print following
// *
// **
// ***
// ****
for (int a = 1; a < 5; a++) {
  for (int i = 0; i < a; i++) {
    System.out.print("*");
  } // inner of for
  System.out.println();
} // outer of for

// print following
// *
// ***
// *****
// *******
// *********
for (int a = 1; a < 10; a+=2) {
  for (int i = 0; i < a; i++) {
    System.out.print("*");
  } // inner of for
  System.out.println();
} // outer of for

// print following
// ****
// ***
// **
// *
for (int a = 4; a > 0; a--) {
  for (int i = 0; i < a; i++) {
    System.out.print("*");
  } // inner of for
  System.out.println();
} // outer of for