Thread: Array and Objects trouble

I'm trying to set the method "setArray()" with the values of "dimension" and "points" entered by a user. When I try to print it by calling the "getArray()" method, it prints "[[D@6818c458". Why is this happening?

Main Program:

import java.io.*;
import java.util.Arrays;
 
public class mainClass
{
  public static void main (String [] args) throws IOException
  {
    BufferedReader myInput = new BufferedReader (new InputStreamReader(System.in));//buffered reader
 
    arrayObjects objects;
 
    objects = new arrayObjects();
 
    int points = 0, dimension = 0;
    double lengthA = 0;
 
    PrintWriter fileOut = new PrintWriter (new FileWriter ("arrayPoints.txt"));//writes to arrayPoints.txt file
 
    System.out.println("How many dimensions do you want?");
    String dimensionA = myInput.readLine();
    dimension = Integer.parseInt(dimensionA);
    objects.setDimension(dimension);
 
    System.out.println("How many points do you want?");
    String pointsA = myInput.readLine();
    points = Integer.parseInt(pointsA);
    objects.setNumPoints(points);
 
    System.out.println("Enter a range: ");
    String lengthB = myInput.readLine();
    lengthA = Double.parseDouble(lengthB);
    objects.setRange(lengthA);
 
    objects.setArray(dimension, points);
 
    double[][] dataPoints = objects.getArray();
 
 
    System.out.println(objects.getDimension());
    System.out.println(objects.getRange());
    System.out.println(objects.getNumPoints());
     }
}

Object Class

import java.io.*;
import java.util.Arrays;
 
public class multiDimArrayObjects
{
  private int dimension;
  private double lengthA;
  private int points;
  private double [][] dataPoints;
  private double [] length;
 
 
  public multiDimArrayObjects(){
  }
 
  public multiDimArrayObjects(double[][] datapoints)
  {
   lengthA = 0;
   points = 0;
   dimension = 0;
   dataPoints = new double [points][dimension];
   length = new double [dimension];
  }
  public multiDimArrayObjects(double myLength, int myPoints, int myDimension, double[][] dataPoints, double [] length){
   lengthA = myLength;
   points = myPoints;
   dimension = myDimension;
   dataPoints = new double [points][dimension];
   length = new double [dimension];
  }
  public double[][] getArray(){
    return dataPoints;
  }
  public void setArray(int dimension, int points){
    dataPoints = new double [points][dimension];
   for (int i=0; i < dataPoints.length; i++)
    {
      for (int j =0; j < dataPoints[i].length; j++)
      {
        System.out.println(dataPoints[i][j]);
 
         }
    }
 }
  public int getDimension(){
    return dimension;
  }
  public void setDimension(int myDimension){
    dimension = myDimension;
  }
 
  public int getNumPoints(){
    return points;
  }
 
  public void setNumPoints(int myNumPoints){
  points = myNumPoints;
  }
 
  public double getRange(){
  return lengthA;
  }
 
  public void setRange(double myRange){
  lengthA = myRange;
  }
 
  public void fillArray(double [][] dataPoints, double lengthA, int dimension, int points)throws IOException
  {
   // PrintWriter fileOut = new PrintWriter (new FileWriter ("arrayPoints.txt"));//writes to arrayPoints.txt file
 
    for(int z = 0; z < dimension; z++){//fills the length array with the the set value of lengthA
      length[z] = lengthA;
      }//end for
 
    for(int x = 0; x < points; x++){//runs 1000 times to print 1000 data points
      for (int y = 0; y < dimension; y++){//runs 2 times to print an x and y coordinate
        dataPoints [x][y]= (2 *Math.random() - 1) * length[y];// finds a random number in the range and assigns it to the coordinate array
      }//end for
    }//end for
 
  }
 
  public void readData()throws IOException
  {
  BufferedReader readfile = new BufferedReader(new FileReader("arrayPoints.txt"));//reads data from arrayPoints.txt
    try {//try statement
        StringBuilder file = new StringBuilder();
        String line = readfile.readLine();//assigns line data from file
 
        while (line != null) {//run while line isn't empty
            file.append(line);
            file.append('\n');
            line = readfile.readLine();
        }//end while
        String finalData = file.toString();//converts to a string
       System.out.print(finalData);//prints the coordinate
    } //end try
    finally {//close file when done
        readfile.close();
    }//end finally
  }//end readFile
 
 
  public void writeData(double[][] dataPoints, int points)throws IOException
  {
    PrintWriter fileOut = new PrintWriter (new FileWriter ("arrayPoints.txt"));//writes to arrayPoints.txt file
 
    for (int i = 0; i < points; i++){
      fileOut.println(Arrays.toString(dataPoints[i]));//converts array to string and prints to file
                      }//end for
      fileOut.close();//writes to file
      readData();// calls readFile method
 
  }
  public static void sortArray(double [] dataPoints,int low, int n){
 
    int lo = low;
    int hi = n;
    if (lo >= n) {
      return;
    }
    double mid = dataPoints[(lo + hi) / 2];
    while (lo < hi) {
      while (lo<hi && dataPoints[lo] < mid) {
        lo++;
      }
      while (lo<hi && dataPoints[hi] > mid) {
        hi--;
      }
      if (lo < hi) {
        double T = dataPoints[lo];
        dataPoints[lo] = dataPoints[hi];
        dataPoints[hi] = T;
      }
    }
    if (hi < lo) {
      int T = hi;
      hi = lo;
      lo = T;
    }
    sortArray(dataPoints, low, lo);
    sortArray(dataPoints, lo == low ? lo+1 : lo, n);
  }
}

Originally Posted by GoodbyeWorld

You're better using a for loop

double[][] array = objects.getArray();
 
 
for (int i=0; i < array.length; i++)
{
for (int j =0; j < array[i].length; j++)
{
System.out.println(array[i][j]);
 
 
}
}

I have made changes based on your answer. When ran, it will print the number of points the user asked for, however it only prints zeros. Is there an error happening when I set the array to the values of "points" and "dimension" to cause this to happen? (I have changed the code above to the updated code). Thanks

Originally Posted by GoodbyeWorld

Since you didn't call fillArray(), the data never got inserted into it, hence it was still in java's default initialization.

So would i call the fillArray() before I send "dimension" and "points" into setArray() by adding this,

 
    objects.fillArray(objects.getArray(), objects.getRange(), objects.getDimension(), objects.getNumPoints());
 
    objects.setArray(dimension, points);
 
    double[][] dataPoints = objects.getArray();