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Two-Dimensional Array

A two-dimensional array is equivalent to a matrix in mathematics. (If you're unfamiliar with matrices, don't worry; I'll explain them simply right now.) While two-dimensional arrays aren't commonly used in practical programming, it's important to understand them and the ability to create multi-dimensional arrays. A two-dimensional array is an array with two distinct indices.

To illustrate, let's examine a diagram of a two-dimensional array:

The table above serves as an example of a two-dimensional array or matrix. Let's explore how to retrieve values from this table. For instance, suppose we want to find the element at index [3][2]. The first index indicates the row we will examine, and the second indicates the column. Visualizing two lines mentally can help us arrive at the result:

We draw two lines intersecting at the cell with the number 18. This represents the value at index [3][2].

I hope you now have a clear understanding of how matrices work. Next, let's explore how to declare a two-dimensional array in code, and then we'll demonstrate how to populate it manually. Following that, we will conduct an index-based search to confirm our accuracy.

Main


              1234567891011121314151617
            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[][] twoDimensionalArray = new int[3][3];
        twoDimensionalArray[0][0] = 1;
        twoDimensionalArray[0][1] = 2;
        twoDimensionalArray[0][2] = 3;
        twoDimensionalArray[1][0] = 4;
        twoDimensionalArray[1][1] = 5;
        twoDimensionalArray[1][2] = 6;
        twoDimensionalArray[2][0] = 7;
        twoDimensionalArray[2][1] = 8;
        twoDimensionalArray[2][2] = 9;
        System.out.println(twoDimensionalArray[2][1]);
    }
}

As you can see, we declared a two-dimensional array with dimensions 3 x 3. However, manually filling it proved to be quite time-consuming and challenging. You might already be contemplating how we can utilize a loop to efficiently populate the array or extract all the data from it. We will delve into that topic in the next chapter.

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