Sheet 01 — Declare & Initialize
Build the block
An array is one contiguous, fixed-length block of same-typed slots. Type your own values below and watch the block get allocated.
int[] arr = new int[]{ ... };
Sheet 02 — Traverse
Walk every index
A for-loop visits index 0 through length−1 in order. Watch the pointer move and the running sum update.
Current index—
Running sum0
for (int i = 0; i < arr.length; i++) {
sum += arr[i];
}
Press "Run traversal" to step through the array.
Sheet 03 — Linear Search
Find a value
No shortcuts — check each cell left to right until the target turns up, or the array runs out.
for (int i = 0; i < arr.length; i++) { if (arr[i] == target) return i; } return -1; // not found
Enter a target and press Search.
Sheet 04 — Bubble Sort
Order the block
Repeatedly compare neighbors and swap out-of-order pairs. Not the fastest sort — but the clearest one to watch.
Comparisons0
Swaps0
Pass—
for (int i = 0; i < n-1; i++) for (int j = 0; j < n-i-1; j++) if (arr[j] > arr[j+1]) { int tmp = arr[j]; arr[j] = arr[j+1]; arr[j+1] = tmp; }
Press "Run sort" to watch bubble sort work.
Sheet 05 — Two Dimensions
An array of arrays
arr2d[row][col] — a grid where each row is itself a full array. Click a cell to see its address.
int[][] grid = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}
};
Click any cell in the grid to inspect it.