程序编译但未正确写入文件

Question

The program compiles but when it writes to a file this is what comes up:

[[D@92ca580, [D@52257b34, [D@1abbbd0e, [D@1b78efd8..... and it keeps going on

Whats wrong with my code? Did I structure it properly? Also when calling the writefile method in the main method, did I do it correctly?

UPDATE** I fixed it up and now this what comes up on the file:

[[0.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0]...

I think the problem is that i didnt directly call the writefile method.. is that why? and how can i fix it?

 import java.io.*;

public class j4 {
  public static void main (String [] args) throws IOException
  {
    int numpoints = 100, dimension = 2, length = 100;//numpoints is set to 100, dimension is set to 2, length is set to 100

    //arrays are initializewd and declared
    double [] lengthscale = new double [dimension];
    double [][] locations = new double [numpoints][dimension];

    PrintWriter fileOut = new PrintWriter (new FileWriter ("arrayNumPoints.txt"));

    for(int m=0; m <length; m++){//for loop
      fileOut.println(java.util.Arrays.toString(locations) + ", ");//writes to file
    }
    fileOut.close ();//close file

  }//end main

  public static Double writefile(Double locations[][], Double lengthscale[], int dimension, int numpoints, Double length)throws IOException
  {

    for (int a = 0; a < dimension; a++){//for loop runs while a is less than dimension
      lengthscale[a] = length;//stores array
    }//end for loop

    for (int x=0; x < numpoints; x++){//for loop runs while x is less than numpoints
      for (int y=0; y < dimension; y++){//nested for loop runs while y is less than dimension
        locations [x][y]= (2 * Math.random() - 1) * lengthscale[y];//creates the range and choses random point within 
          return locations[x][y];

      }//end nested for loop
    }//end for loop

    //if program doesnt run through loop.. alternative return statement (but
     double b= 1;    
     return b;
  }//end writefile methos
}//end class

Answer 1

Arrays.toString() does only create a string for your first array. locations is a multi dimensional array (the array values contain another array).

You should try Arrays.deepToString() instead:

Returns a string representation of the "deep contents" of the specified array. If the array contains other arrays as elements, the string representation contains their contents and so on. This method is designed for converting multidimensional arrays to strings.

Answer 2

Try using Arrays.deepToString instead, which

Returns a string representation of the "deep contents" of the specified array. If the array contains other arrays as elements, the string representation contains their contents and so on. This method is designed for converting multidimensional arrays to strings .

The assumption, however, is that you don't want the numbers printed in a specific format. In that case you are probably left with the choice of looping over the elements and printing them with desired formatting.

In my opinion the above method is rather useful for logging/debugging operations.