无法使用for循环在java中初始化二维数组

Question

I can not initialize a two dimensional array using for loop

import java.util.Scanner;

   public class Quater{
      public static void main(String[] args){
        //declare an array
        double product[][]=new double[3][2];

        //declare a Scanner object
        Scanner userInput=new Scanner(System.in);

        //ask the user for input

        System.out.println("Please enter your data");
        for(int i=0;i<=1;i++)
        {
          for(int j=0;j<=2;j++){
          System.out.println(" enter your data");

          product[i][j]=userInput.nextDouble();
        } 
      }
    }
  }

The problem is when I try to enter the third number, This shut down and not working, however, if I make it new double[100][100], this can work and allow me to enter 6 number.

Answer 1

外循环遍历行和内部遍历列，因此您需要具有double[2][3]精度数组double[2][3] ，而不是您使用的double[3][2] 。

Answer 2

If you make your array new double[3][2] , then you can access product[i][j] where i goes up to 3-1=2, and j goes up to 2-1=1. That is, the bounds of the indexes in the same order in which they appear in the new . But you're trying to access product[i][j] where j is 2.

Answer 3

Corrected code. Look on this. Condition of two fors was fixed. You should do it using length and better is using '<' not '<='. That prevent you from many ArrayIndexOutOfBoundsException .

public static void main(String[] args){
            //declare an array
            double product[][]=new double[3][2];

            //declare a Scanner object
            Scanner userInput=new Scanner(System.in);

            //ask the user for input

            System.out.println("Please enter your data");
            for(int i=0;i<product.length;i++)
            {
                for(int j=0;j<product[i].length;j++){
                    System.out.println(" enter your data");

                    product[i][j]=userInput.nextDouble();

                }
            }
        }

to see the efect you can simply paste down that code.

for (double[] doubles : product) {
                for (double aDouble : doubles) {
                    System.out.println(aDouble);
                }
            }