Using an Expression as an Index

Using an expression for an array index is a very powerful tool. You often solve a problem by organizing the data into arrays, and then processing that data in a systematic way using variables as indexes. Here is a further example:

class ArrayEg2
{
  public static void main ( String[] args )
  {
    double[] val = new double[4];  // an array of double 
                                   // cells initialized to 0.0
    val[0] = 0.12;
    val[1] = 1.43;
    val[2] = 2.98;

    int j = 3;
    System.out.println( "cell 3: " + val[ j   ] );
    System.out.println( "cell 2: " + val[ j-1 ] );

    j = j-2;
    System.out.println( "cell 1: " + val[ j   ] );
   }
}

You can, of course, copy this program to your editor, save it and run it. Arrays can get confusing. Playing around with a simple program now will pay off later.