Recitation 7 Code

1. I don't remember what this was for, but here it is!

     FillWithSevens.java 

  1  public class FillWithSevens {
  2      public static void main(String[] args) {
  3          int[] x = new int[3];
  4  
  5          for (int i=0; i<3; i++) {
  6              x[i] = 7;
  7          }
  8      }
  9  }

2. Modifying an array:

     ModifyArray.java 

  1  class ModifyArray {
  2      public static void main(String[] args) {
  3          int[] x = { 1, 1 };
  4          int[] y = x;
  5  
  6          y[0] = 3;
  7  
  8          System.out.println(x[0]);
  9      }
 10  }

3

3. Reverse an array in a new array:

     ReverseNewArray.java 

  1  public class ReverseNewArray {
  2      public static void main(String[] args) {
  3          int[] x = { 1, 2, 3 };
  4  
  5          int[] y = new int[x.length];
  6  
  7          int len = x.length;
  8          int j = 0;
  9          for (int i=len-1; i>=0; i--) {
 10              y[j] = x[i];
 11              System.out.println(java.util.Arrays.toString(y));
 12              j++;
 13          }
 14          System.out.println(java.util.Arrays.toString(x));
 15      }
 16  }

[3, 0, 0]
[3, 2, 0]
[3, 2, 1]
[1, 2, 3]

4. Reverse an array in place:

     ReverseInPlace.java 

  1  public class ReverseInPlace {
  2      public static void main(String[] args) {
  3          int[] x = { 1, 2, 3, 4, 5, 6, 7, 8 };
  4  
  5          int j = x.length-1;
  6          for (int i=0; i<x.length/2; i++) {
  7              int f = x[i];
  8              x[i] = x[j];
  9              x[j] = f;
 10              System.out.println(java.util.Arrays.toString(x));
 11              j--;
 12          }
 13      }
 14  }

[8, 2, 3, 4, 5, 6, 7, 1]
[8, 7, 3, 4, 5, 6, 2, 1]
[8, 7, 6, 4, 5, 3, 2, 1]
[8, 7, 6, 5, 4, 3, 2, 1]