Java 多維數組的完整指南。數組是同質資料多維結構,是具有相似資料類型的元素的集合。它們儲存在連續的記憶體位置中。在陣列中,第一個元素儲存在索引 0 中;第二個元素儲存在索引 1 中,依此類推。數組可以是單維或多維的。在本文檔中,我們將研究 Java 中的多維數組。多維數組是可以容納多個行和列的數組的數組。現在,讓我們在以下部分中了解多維數組的語法和實作。
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data_type[dimension 1][dimension 2][]…[dimension n] array_name= new data_type[size 1][size 2]…[size n]
Java 中最常見的多維數組是:
二維數組通常用於超級瑪利歐等平台電玩遊戲中來表示地形或螢幕。它們也可以用於繪製棋盤、表示電子表格等結構。
代碼:
int[][] array1 = new int[2][2];//Two dimensional Integer Array with 2 rows and 2 columns
範例:
9 10
7 66
這是一個兩行兩列的二維陣列。
三維數組在即時應用程式中並不常用。因此,在程式設計範例中也更傾向於二維數組。
代碼:
int[][][] array2 = new int[12][24][36]; //Three dimensional Array
範例:
6 8 66
66 65 47
46 89 98
如果知道普通數組,就很容易理解 Java 中的多維數組。多維數組可以如下聲明:
首先讓我們來看看二維陣列的宣告:
確保在 Java 程式設計時建立正確的聲明。
代碼:
//Java Program to demonstrate the multidimensional 2D array public class MultidimensionalArray { public static void main(String args[]){ //2D array a is declared and initialized int a[][]={{2,2,3},{8,4,5},{9,4,5}}; //Print the array elements for(int i=0;i<3;i++){ for(int j=0;j<3;j++){ System.out.print(a[i][j]+" "); } System.out.println(); } }}
輸出:
三維數組的聲明可以討論。
這些陣列可以是任何資料型態。以下是一些具有不同資料類型的三維數組。
代碼:
//Java Program to demonstrate the multidimensional array public class MultidimensionalArray { //main method public static void main(String[] args) { //3D array arr int[][][] arr = { { { 1 , -9 , 3 } ,{ 2 , 7 , 4 } } , { { -45 , -5 , 6 , 75 } , { 88 } , { 29 , 30 } } }; // for..each loop to iterate through the elements of the 3d array arr for (int[][] ar: arr) { for (int[] a: ar) { for(int finalarray: a) { System.out.println(finalarray); } } } } }
輸出:
多維數組可以用多種方式初始化:
In a more traditional way, Initializing Array elements can be as follows.
int[][][] a = { { { 11 , 23 , 30 }, { 5 ,65 , 70 } , { 0 , 80 , 10 } ,{ 10 , 12 , 450 } } ,{ { 33 , 2 , 4 } , {11, 66, 6}, {55, 11, 22}, {11, 57, 43} } };
In this case, even though the size of rows and columns are not mentioned, the java compiler is able to identify the size of rows and columns by counting the number of elements.
In the case of storing a large number of elements, Nested For Loop can be used as shown below:
int i, j, k; for(i = 0; i < 2; i++) { for(j = 0; j < 3; j++) { for(k = 0; k < 4; k++) { a[i][j][k] = i + j + k;} } }
int a= new int[3][2][4]; a[0][2][1]= 33; a[0][1][2]= 73; a[0][1][1]= 88;
A three-dimensional array of size 3 levels * 2 rows * 4 columns is created, but values are assigned to some positions only. Since none of the other elements does have any value assigned, default values will be assigned.
Multidimensional Array in Java can perform several operations.
Let Us See the Matrix Addition of Two Arrays.
Code:
import java.util.*; //Java Program to demonstrate the multidimensional array public class MultidimensionalArray { //main method public static void main(String args[]) { int row, col, c, d; //input the number of rows and columns Scanner <u>in</u> = new Scanner(System.in); System.out.println("Enter the number of rows of matrix"); row = in.nextInt(); System.out.println("Enter the number of columns of matrix"); col = in.nextInt(); //initialization of two matrices and sum matrix int firstmat[][] = new int[row][col]; int secondmat[][] = new int[row][col]; int summat[][] = new int[row][col]; //adding elements to first matrix System.out.println("Enter the elements to be added to the first matrix"); for (c = 0; c < row; c++) for (d = 0; d < col; d++) firstmat[c][d] = in.nextInt(); //adding elements to second matrix System.out.println("Enter the elements to be added to the second matrix"); for (c = 0 ; c < row ; c++) for (d = 0 ; d < col ; d++) secondmat[c][d] = in.nextInt(); //sum of the two matrices for (c = 0; c < row; c++) for (d = 0; d < col; d++) summat[c][d] = firstmat[c][d] + secondmat[c][d]; System.out.println("Sum of the two given matrices is:"); //printing the sum matrix for (c = 0; c < row; c++) { for (d = 0; d < col; d++) System.out.print(summat[c][d]+"\t"); System.out.println(); } } }
Output:
If subtraction needs to be performed, replace ‘+’ with ‘-‘ in the code.
Let us see how Matrix Multiplication Works.
Code:
import java.util.*; //Java Program to perform matrix multiplication public class MultidimensionalArray { //main method static int N = 4; // multiply matrices a and b, and then stores the result in c static void mul(int a[][], int b[][], int c[][]) { int i, j, k; for (i = 0; i < N; i++) { for (j = 0; j < N; j++) { c[i][j] = 0; for (k = 0; k < N; k++) c[i][j] += a[i][k] * b[k][j]; //multiply a and b matrices } } } //main method public static void main (String[] args) { int a[][] = { {9, 7, 2, 3}, {9, 7, 2, 3}, {4, 13, 32, 2}, {9, 7, 2, 3}}; int b[][] = {{ 9, 7, 2, 3}, {9, 7, 2, 3}, {9, 7, 2, 3}, {4, 13, 32, 2}}; // Store the result in c int c[][] = new int[N][N] ; int i, j; mul(a, b, c); //calling the mul method System.out.println("Multiplication result matrix" + " is "); for (i = 0; i < N; i++) { for (j = 0; j < N; j++) System.out.print( c[i][j] + " "); System.out.println(); } } }
Output:
Arrays are homogenous data structures that can store similar types of elements. It can be of single-dimensional or multidimensional. In this document, multidimensional arrays are discussed with explaining the syntax structure, initialization, etc.
This is a guide to Multidimensional Array in Java. Here we discuss 2 types of the multidimensional array in java, how to declare, how to initialize and operation in it. You can also go through our other related articles to learn more –
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