Java 鋸齒狀陣列

Mehvish Ashiq 2022年4月26日
Java 鋸齒狀陣列

本教程介紹了 Java 鋸齒狀陣列。我們將通過不同的程式碼示例瞭解它的記憶體表示和實現。

Java 鋸齒狀陣列

要理解鋸齒狀陣列,你必須對陣列有一個很好的理解。鋸齒狀陣列,也稱為不規則陣列,是一個陣列,其中每個成員陣列的大小都不同。

這裡,陣列陣列是指二維陣列;它可以是 2D 或 3D 或更多維度。請參閱以下視覺演示以瞭解鋸齒狀陣列。

java 鋸齒狀陣列——視覺化演示

我們可以看到每個成員陣列的大小互不相同。這就是我們所說的鋸齒狀或鋸齒狀陣列。

Java 中鋸齒狀陣列的宣告與初始化

有多種方式來宣告和初始化鋸齒狀陣列;我們將在下面使用從視覺解釋中提取的 int 型別陣列來檢視它們中的每一個。

使用第一種方法,我們首先通過指定大小來宣告基本陣列。然後,我們為每個成員陣列寫入不同的大小。

在這裡,我們將宣告和初始化過程分開。請參閱以下程式碼段。

宣告鋸齒狀陣列:

//declare base array of size 4 (it would be an array of arrays)
int arr[][] = new int[4][];

//declare member arrays
arr[0] = new int[3]; //here the 3 shows the no of columns in row-1
arr[1] = new int[4]; //here the 4 shows the no of columns in row-2
arr[2] = new int[1]; //here the 1 shows the no of columns in row-3
arr[3] = new int[2]; //here the 2 shows the no of columns in row-4

接下來,靜態初始化鋸齒狀陣列。

arr[0] = new int[]{1,2,3};
arr[1] = new int[]{1,2,3,4};
arr[2] = new int[]{4};
arr[3] = new int[]{4,5};

或者,我們可以動態初始化鋸齒狀陣列,這意味著我們從使用者那裡獲取輸入並在執行時初始化陣列。

Scanner sc = new Scanner(System.in);

for (int base = 0; base < arr.length; base++) {
     for (int member = 0; member < arr[base].length; member++) {
          arr[base][member] = sc.nextInt();
     }
}

在第二種方法中,我們可以一步宣告和初始化鋸齒狀陣列。我們可以用各種方式編寫這一步。

請參閱下面給出的程式碼片段。

int arr[][] = new int[][]{
              new int[] {1, 2, 3},
              new int[] {1, 2, 3, 4},
              new int[] {4},
    		  new int[] {4, 5}
            };

                              OR

int[][] arr = {
              new int[] {1, 2, 3},
              new int[] {1, 2, 3, 4},
              new int[] {4},
    		  new int[] {4, 5}
             };

                              OR

int[][] arr = {
              	{1, 2, 3},
                {1, 2, 3, 4},
                {4},
                {4, 5}
 			};

讓我們深入瞭解鋸齒狀陣列的更詳細實現,我們將在其中靜態和動態地分配值。

Java 中的鋸齒狀陣列實現示例

示例程式碼(鋸齒狀陣列是靜態初始化的):

public class jagggedArrayTest {
    public static void main(String args[]) {

        int arr[][] = new int[][]{
            new int[] {1, 2, 3},
            new int[] {1, 2, 3, 4},
            new int[] {4},
            new int[] {4, 5}
          };

        for (int base = 0; base < arr.length; base++) {
            System.out.print("arr["+base+"] ======> {");
            for (int member = 0; member < arr[base].length; member++) {
                if(member < arr[base].length - 1)
                    System.out.print(arr[base][member] + ", ");
                else
                    System.out.print(arr[base][member]);
            }
            System.out.print("}");
            System.out.println();
        }
    }
}

輸出:

arr[0] ======> {1, 2, 3}
arr[1] ======> {1, 2, 3, 4}
arr[2] ======> {4}
arr[3] ======> {4, 5}

我們首先在 main 函式中宣告並初始化鋸齒狀陣列。然後,我們使用巢狀的 for 迴圈來列印鋸齒狀陣列,其中外迴圈用於迭代基本陣列(行),而內迴圈用於迭代成員陣列(列)。

示例程式碼(動態填充鋸齒狀陣列):

import java.util.Scanner;

public class jaggedArrayTest {

    /*
    this function prints the populated jagged array
    */
    static void printJaggedArray(int[][] arr){

        System.out.println("The populated array looks like as follows:");

        for (int base = 0; base < arr.length; base++) {
            System.out.print("arr["+base+"] ======> {");

            for (int member = 0; member < arr[base].length; member++) {
                if(member < arr[base].length - 1)
                    System.out.print(arr[base][member] + ", ");
                else
                    System.out.print(arr[base][member]);
            }

            System.out.print("}");
            System.out.println();
        }
    }
    /*
    this function populates the jagged array by
    taking input from the user
    */
    static void populateJaggedArray(int[][] arr){
        Scanner sc = new Scanner(System.in);

        for (int base = 0; base < arr.length; base++) {
            System.out.println("Enter the member array at index " + base);

            for (int member = 0; member < arr[base].length; member++) {
          		arr[base][member] = sc.nextInt();
     		}
		}
        //print jagged array
        printJaggedArray(arr);
    }

    public static void main(String args[]) {

        //declare base array of size 4 (it would be an array of arrays)
		int arr[][] = new int[4][];

		//declare member arrays
		arr[0] = new int[3]; //here the 3 shows the no of columns in row-1
		arr[1] = new int[4]; //here the 4 shows the no of columns in row-2
		arr[2] = new int[1]; //here the 1 shows the no of columns in row-3
		arr[3] = new int[2];  //here the 2 shows the no of columns in row-4

        //populate jagged array
        populateJaggedArray(arr);
    }
}

輸出:

Enter the member array at index 0
1 2 3
Enter the member array at index 1
1 2 3 4
Enter the member array at index 2
4
Enter the member array at index 3
4 5
The populated array looks like as follows:
arr[0] ======> {1, 2, 3}
arr[1] ======> {1, 2, 3, 4}
arr[2] ======> {4}
arr[3] ======> {4, 5}

在這裡,我們在 jaggedArrayTest 類中擁有三個名為 main()populateJaggedArray()printJaggedArray() 的方法。main() 方法宣告並初始化鋸齒狀陣列,該陣列被傳遞給 populateJaggedArray() 函式以進行填充。

此外,它呼叫 printJaggedArray() 來列印填充的鋸齒狀陣列。請記住,我們只是動態地填充鋸齒狀陣列,但你也可以使用使用者的輸入值來獲取基本陣列和成員陣列的大小。

Mehvish Ashiq avatar Mehvish Ashiq avatar

Mehvish Ashiq is a former Java Programmer and a Data Science enthusiast who leverages her expertise to help others to learn and grow by creating interesting, useful, and reader-friendly content in Computer Programming, Data Science, and Technology.

LinkedIn GitHub Facebook

相關文章 - Java Array