Java多维数组程序问题

Question

I don't understand why i'm getting these errors when i compile my code.

Error: F:\\G\\programA: operator * cannot be applied to int,double[]

Error: F:\\G\\programA: operator - cannot be applied to double,double[]

import java.io.*;

public class programA
{
  public static void main (String [] args) throws IOException
  {
    BufferedReader myInput = new BufferedReader (new InputStreamReader (System.in));

  int points = 100, dimension = 3;

  double [] length;
  length = new double [dimension];

  double [][] loc;
  loc = new double [points][dimension];

   for (int x = 0; x < points; x++){
  for (int y = 0; y < dimension; y++){
   location [x][y]= (Math.random() * (2 *length)) - length;
  }
  }

  }
}

Answer 1

 2 *length 

You're multiplying an array by an int. Not going to happen. The code around that is somewhat unclear, but since you're trying to set a single array element you'll want to get a single element of length , such as by length[0] or length[someIntInRange] .

Also, location [x][y] should be loc[x][y] as there is no field called location.

Answer 2

Since the code isnt clear, I am assuming you need

loc [x][y]= (Math.random() * (2 *length[y])) - length[y];

Math Operations cannot be done between an array and a number.

Answer 3

I don't understand why i'm getting these errors when i compile my code.

Error: F:\\G\\programA: operator * cannot be applied to int,double[]

Error: F:\\G\\programA: operator - cannot be applied to double,double[]

You are trying to multiply an int and later a double against an array of type double . This is not possible. If you want to multiply against all values in the array, you need to iterate over it to do so.

Answer 4

Your problem is an undefined operation here...

double [] length;
length = new double [dimension];
...
(2 *length)

You need to select a value from the length array.