Section 10.8 Worked Example: Arrays - Initializer List and Reverse Traverse
Subgoals for Evaluating Arrays.
- Set up array from 0 to size-1
- Evaluate data type of statements against array
-
Trace statements, updating slots as you go
- Remember assignment subgoals
Subsection 10.8.1
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Problem: Evaluate these statements and determine their output
int [] alpha = {15, 24, 7, 6, -4, 0, 13};
System.out.println(alpha.length);
for (int i = alpha.length-1; i >= 0; i--)
alpha[i] = alpha[i] + 1;
for (int i = alpha.length-1; i >= 0; i--)
System.out.print(alpha[i]+ " ");
Subsection 10.8.2 SG1: Set up array from 0 to size-1
int [] alpha = {15, 24, 7, 6, -4, 0, 13};

- alpha is declared as an array of ints
- This statement allocates 7 slots for integers because there are 7 literal values given in the initialization list.
Subsection 10.8.3 SG2: Evaluate data type of statements against array
The statement
System.out.println(alpha.length);
will print an output String. Then,for (int i = alpha.length-1; i >= 0; i--)
alpha[i] = alpha[i] + 1;
- This loop has index i go from 6 to 0 by decrements of 1.
- All of the array indexes are within the bounds of the array (6 – 0) and the value of 1 is added to the current value at position i in the array.
- All values being assigned are valid integers and can be stored in an integer array.
The final for-loop will also print output strings.
Subsection 10.8.4 SG3: Trace statements, updating slots as you go
The statement
System.out.println(alpha.length);
will print the value 7 and then a newline return, so that the next output will begin on a new line. Then, the first for-loop will update the array values (without printing them quite yet!)for (int i = alpha.length-1; i >= 0; i--)
alpha[i] = alpha[i] + 1;
The resulting array is:

The final for-loop will print: 14 1 -3 7 8 25 16
Subsection 10.8.5 Practice Pages
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