How to Create a 2D Boolean Array with All Values Set to True Using Java Streams?

How can I construct a Java stream expression that creates a 2D boolean array with all values set to true?

This guide demonstrates how to efficiently create a 2D boolean array filled with 'true' values using Java Streams. By leveraging the Streams API, you can create arrays dynamically based on specified dimensions.

int rows = 5;  // number of rows
int cols = 4;  // number of columns
boolean[][] result = java.util.stream.IntStream.range(0, rows)
        .mapToObj(i -> java.util.stream.IntStream.range(0, cols)
        .mapToObj(j -> true)
        .toArray(Boolean[]::new))
        .toArray(boolean[][]::new);

Causes

• Not using the appropriate stream methods for array initialization.
• Mistaking the dimensionality of the boolean array.

Solutions

• Use the Stream.generate() method to generate boolean arrays initialized to true.
• Utilize IntStream to create the rows and columns of the boolean array.

Mistake: Trying to initialize the array directly without streams.

Solution: Use the stream-based approach to fill each row with true values.

Mistake: Forgetting to map to Boolean arrays instead of primitive types.

Solution: Ensure mapping to Boolean arrays using the appropriate Stream methods.