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Modern Java: From Fundamentals to Advanced Architecture

Common Array Operations

Explore how to handle common array tasks in Java using the java.util.Arrays class. Learn to print arrays clearly, fill them with values, sort data, perform fast searches, compare arrays accurately, and copy or resize arrays. This lesson helps you write cleaner, faster, and more reliable array code without manual loops.

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We normally use for loops to print array elements, find values, or copy data. While this works for learning the mechanics, writing these loops manually for every task is slow, repetitive, and prone to errors.

Professional Java developers rely on the standard java.util.Arrays class. This utility class is a toolbox containing highly optimized static methods that handle these common operations for us. By using this toolkit, we make our code more readable, faster, and less buggy.

The power of java.util.Arrays

One of the first frustrations beginners face is trying to print an array directly. If we pass an array object to System.out.println(), Java prints its memory reference (technically a type signature and hash code) rather than the actual numbers or strings inside.

To fix this, we use Arrays.toString(). This method converts a simple (one-dimensional) array into a nicely formatted string with brackets and commas. However, if we try this on a multi-dimensional array (like a matrix), Arrays.toString() only prints the memory references of the inner arrays. ...

Java 25
import java.util.Arrays;
public class ArrayPrinting {
    public static void main(String[] args) {
        // A simple 1D array
        int[] numbers = {1, 2, 3};
        
        // A 2D array (matrix)
        String[][] matrix = {
            {"A", "B"},
            {"C", "D"}
        };
        // 1. Trying to print directly (Unhelpful output)
        System.out.println("Direct Print: " + numbers);
        // 2. Using Arrays.toString() for 1D arrays
        System.out.println("Arrays.toString: " + Arrays.toString(numbers));
        // 3. Using Arrays.deepToString() for 2D arrays
        System.out.println("Arrays.deepToString: " + Arrays.deepToString(matrix));
    }
}
    ...