Question

4x6的简单2d数组

public class arraytest {

public static void main(String[] args) {
int array[][] = new int[4][6];
int row = array.length;
int col = array[0].length;

System.out.println("Row length " + row);
for (int i = 0; i < row; i++)
    for (int j = 0; j < col; j++) {
    array[1][1] = 5;
    System.out.println("Array elements " + array[i][j]);
    }
}

}

array [1] [1] = 5函数如何：输出如下：

Row length 4
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 5
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0
Array elements 0

怎么来＆＃34;数组元素5＆＃34;在第8位，我无法理解逻辑。＆gt;任何人都可以解释这个逻辑。

Answer 1

使用数组时，您必须知道第一个元素始终存储在0索引中。我假设通过键入array [1] [1]，您希望将值5存储在第一行第一列中。然而，由于上述原因，[1] [1]实际上是指第二行第二列。

因此你的数组看起来像这样：

0 0 0 0 0 0
0 5 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0

最后，因为你的for循环将列作为最里面的循环，所以它会在移动到第二行之前打印出第一行中的每一列。因此，在您最终达到设置为第八个输出的值之前，第一行输出六个0，第二行输出另一个0。

Answer 2

array [1] [1]表示第二行和第二列的交集。因此，循环首先打印第一行（有6个元素），在第二行打印数组[1] [0]和数组[1] [1]。因此，数组[1] [1]位于第8位。

Answer 3

您正在将元素1,1设置为5 ......其余元素将保持相同的值...

Row length 4 
Array elements 0 
Array elements 0 
Array elements 0 
Array elements 0 
Array elements 0 
Array elements 0 
Array elements 0
Array elements 5  <--- here is he!!
Array elements 0 
Array elements ...

Answer 4

我认为您忘记了数组索引从 0 开始！

这意味着一个4乘6的多维数组看起来像这样：

[0] [0] [0] [1] [0] [2] [0] [3] [0] [4] [0] [5] [1] [0] [1] [1] [1] [2] [1] [3] [1] [4] [1] [5] [2] [0] [2] [1] [2] [2] [2] [3] [2] [4] [2] [5] [3] [0] [3] [1] [3] [2] [3] [3] [3] [4] [3] [5]

正如你所看到的那样[1] [1]位于8位。

当你声明一个像这个数组[4] [6]这样的多维数组时，它会从0到3以及从0到5的那些行，因为数组索引从0开始而不是1。

Answer 5

如果您是Java新手，数组将以索引0开头;就像String的第一个char是0.考虑长度，或者数组或String的最终索引为n-1。这个0索引逻辑也将应用于2D数组的列/行。

Answer 6

请参阅此示例的输出，您的疑问将会明确：

public class arraytest {

public static void main(String[] args) {
int array[][] = new int[4][6];
int row = array.length;
int col = array[0].length;

System.out.println("Row length " + row);
System.out.println("Col length " + col);
for (int i = 0; i < row; i++)
    for (int j = 0; j < col; j++) {
    array[1][1] = 5;
    System.out.println("Array elements at row "+i+" and column "+j+" is "+ array[i][j]);
    }
}

}

<强>输出：

Row length 4                                                                                                                                                                    
Col length 6                                                                                                                                                                    
Array elements at row 0 and column 0 is 0                                                                                                                                       
Array elements at row 0 and column 1 is 0                                                                                                                                       
Array elements at row 0 and column 2 is 0                                                                                                                                       
Array elements at row 0 and column 3 is 0                                                                                                                                       
Array elements at row 0 and column 4 is 0                                                                                                                                       
Array elements at row 0 and column 5 is 0                                                                                                                                       
Array elements at row 1 and column 0 is 0                                                                                                                                       
Array elements at row 1 and column 1 is 5                                                                                                                                       
Array elements at row 1 and column 2 is 0                                                                                                                                       
Array elements at row 1 and column 3 is 0                                                                                                                                       
Array elements at row 1 and column 4 is 0                                                                                                                                       
Array elements at row 1 and column 5 is 0                                                                                                                                       
Array elements at row 2 and column 0 is 0                                                                                                                                       
Array elements at row 2 and column 1 is 0                                                                                                                                       
Array elements at row 2 and column 2 is 0                                                                                                                                       
Array elements at row 2 and column 3 is 0                                                                                                                                       
Array elements at row 2 and column 4 is 0                                                                                                                                       
Array elements at row 2 and column 5 is 0                                                                                                                                       
Array elements at row 3 and column 0 is 0                                                                                                                                       
Array elements at row 3 and column 1 is 0                                                                                                                                       
Array elements at row 3 and column 2 is 0                                                                                                                                       
Array elements at row 3 and column 3 is 0                                                                                                                                       
Array elements at row 3 and column 4 is 0                                                                                                                                       
Array elements at row 3 and column 5 is 0

显示2d数组的元素

6 个答案: