A nested for loop is a for loop that is contained within another for loop. It allows you to iterate over a set of values multiple times, with the inner loop completing all of its iterations for each iteration of the outer loop.
Here’s an example of a nested for loop in Java:
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 2; j++) {
System.out.println("i is " + i + ", j is " + j);
}
}
In this example, the outer for loop will iterate three times, with the variable i taking on the values 0, 1, and 2. For each iteration of the outer loop, the inner for loop will iterate twice, with the variable j taking on the values 0 and 1. This means that the code inside the inner loop will be executed a total of six times, with the values of i and j being printed to the console each time.
Here’s the output of this code:
i is 0, j is 0
i is 0, j is 1
i is 1, j is 0
i is 1, j is 1
i is 2, j is 0
i is 2, j is 1
You can nest for loops to any depth, but be careful not to create infinite loops or loops that take a long time to complete.
Nested for loops can be useful when you need to iterate over a two-dimensional array or perform a task multiple times with different combinations of input values.