Question

(Checkerboard Pattern of Asterisks) Write an application that uses only the output statements System.out.print( \(" \pm \cdots)\) System.out.print( " " ) ; System.out.println(): to display the checkerboard pattern that follows. A System.out.println method call with no arguments causes the program to output a single newline character. [Hint: Repetition statements are required.

Short answer

Use nested for loops to print an 8x8 grid. The outer loop iterates over rows, and the inner loop alternates between printing spaces and asterisks based on the evenness of the sum of the current row and column indices.

Step-by-step solution

Understand the task and output format

The objective is to create a checkerboard pattern using the specified Java output statements. The pattern should alternate between spaces and asterisks(*) in an 8x8 grid to resemble a checkerboard.

Define the loop structure

Decide on using nested loops; an outer loop to iterate over the rows and an inner loop for the columns. Each row will have 8 characters, alternating between spaces and asterisks.

Implement the outer loop

The outer loop runs 8 times, once for each row of the checkerboard. Use a for loop with a variable, for instance 'row', ranging from 0 to 7.

Implement the inner loop for asterisks and spaces

Within each iteration of the outer loop, implement another for loop that iterates 8 times for the columns. In each iteration check the sum of the row and column index to determine whether to print a space or an asterisk. If the sum is even, print an asterisk; otherwise, print a space.

Insert a line break after each row

After the inner loop completes (which means one row has been printed), use System.out.println() to start a new line before the next iteration of the outer loop begins.

Compile and run the code

After implementing the nested loops, compile the code and fix any syntax errors. Then, execute the code to check if the checkerboard pattern prints out as intended.

Key concepts

Java nested loops

Creating a checkerboard pattern in Java is an excellent exercise for understanding Java nested loops, a fundamental concept in programming. Nested loops consist of an inner loop running inside an outer loop. Each time the outer loop executes once, the inner loop goes through its complete iteration.

To craft a checkerboard, we utilize two for loops; the outer loop creates the rows, while the inner loop creates the columns. The power of the nested loop setup lies in its ability to systematically cover a two-dimensional range, in this case, the 8x8 grid of our checkerboard. The inner loop's execution depends on the state of the outer loop, forming a grid pattern just like a real checkerboard.

Improving the exercise involves ensuring a clear distinction between rows. To do so, one could initiate the inner loop with a conditional check that alternates the starting character (either a space or an asterisk). This reproduces the effect of ‘offset’ rows seen in a checkerboard, ensuring that the pattern generated mimics the alternating squares correctly.

Java output statements

Effective use of Java output statements is crucial for displaying the checkerboard pattern correctly. The System.out.print() and System.out.println() are two primary methods to control the output in Java. The former is used to print text without a newline character, thus continuing on the same line, while the latter prints text followed by a newline character, thus moving to the next line.

In our checkerboard pattern, System.out.print() is used to print either a space or an asterisk without moving to a new line, allowing us to create the sequence of characters that forms the checkerboard on each row. Following the completion of a row's character sequence, System.out.println() is invoked without arguments to simply advance to the next line, preparing for the next row of the pattern to be printed.

To make the code more versatile and easier to adjust, you might employ output statements within a method designed to print either a space or an asterisk. Not only does this make the code cleaner and more readable, but it also makes modifications more manageable, such as changing the pattern size or the characters used.

Control structures in Java

Control structures in Java are pivotal for directing the flow of execution based on conditions, such as in a checkerboard pattern where we decide whether to print a space or an asterisk. Conditional statements such as if-else are used within the loops to control what is outputted on each iteration.

Within our inner loop, we use an if-else structure to check if the current combination of row and column numbers results in an even or odd sum. If the sum is even, an asterisk is printed; otherwise, a space is printed. This condition creates the alternating pattern required for the checkerboard.

Notably, the introduction of more flexible control structures can further enhance this exercise. For example, one might add parameters to the loops, allowing for dynamic generation of different-sized checkerboards. Furthermore, encapsulating the printing logic within a method would simplify the loop's control structure and enhance readability and maintainability of the code.