Question

我尝试使用两种方法将程序写入文件。它编译时没有错误，但是当它写入的文件打开时，只打印带有（0,0）的坐标。它应该从数组中打印10000随机协调。为什么它只打印出（0,0）坐标？我也把退货声明放在正确的位置吗？

import java.io.*;

public class program
{
  public static void main (String [] args) throws IOException
  {

    int points = 10000, dimension = 2, lengthA = 100;//int variables are declared and initialized

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

    double length [] = new double [dimension];//array for length is declared
    double coordinate [][] = new double [points][dimension];//coordinate array is declared

    for (int i = 0; i < points; i++){
      fileOut.println(java.util.Arrays.toString(coordinate[i]));
                      }
      fileOut.close();//writes to file

  }//end main method

    public static double writeTofile (double length[], double coordinate[][], int points, int dimension, int lengthA)
    {
      int x = 0, y = 0;
      for(int z = 0; z < dimension; z++){//fills the length array with the the set value of lengthA
      length[z] = lengthA;
      }

    for(x = 0; x < points; x++){//runs 1000 times to print 1000 data points
      for (y = 0; y < dimension; y++){//runs 2 times to print an x and y coordinate
        coordinate [x][y]= (2 *Math.random() - 1) * length[y];// finds a random number in the range and assiigns it to the coordinate array
      }//end for
    }//end for
    return coordinate[x][y];
  }//main method
}//program

我已经更改了我的代码并进行了编译。但是当你看到它打印到的文件时，会看到随机字母（[D @ 76f1fad1 [D @ 889ec59 ...]）。为什么会这样？

import java.io.*;

public class program
{
  public static void main (String [] args) throws IOException
  {

    int points = 10000, dimension = 2, lengthA = 100;//int variables are declared and initialized

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

    double length [] = new double [dimension];//array for length is declared
    double coordinate [][] = new double [points][dimension];//coordinate array is declared

    writeTofile(length, coordinate, points, dimension, lengthA);

    for (int i = 0; i < points; i++){
      fileOut.println(Arrays.toString(coordinate[i]));
                      }
      fileOut.close();//writes to file

  }//end main method

    public static void writeTofile (double length[], double coordinate[][], int points, int dimension, int lengthA)
    {
      int x = 0, y = 0;
      for(int z = 0; z < dimension; z++){//fills the length array with the the set value of lengthA
      length[z] = lengthA;
      }

    for(x = 0; x < points; x++){//runs 1000 times to print 1000 data points
      for (y = 0; y < dimension; y++){//runs 2 times to print an x and y coordinate
        coordinate [x][y]= (2 *Math.random() - 1) * length[y];// finds a random number in the range and assiigns it to the coordinate array
      }//end for
    }//end for
  }//main method
}//program

Answer 1

您没有使用main方法中的值调用填充坐标数组的方法。

您可以将其命名为：

...
double coordinate [][] = new double [points][dimension];//coordinate array is declared

writeTofile(length, coordinate, points, dimension, lengthA)

for (int i = 0; i < points; i++){
    ...

至于return语句，它位于正确的位置，但它将抛出ArrayIndexOutOfBoundsException，因为它正在访问数组中不存在的偏移量。您想要一个返回值，您对它有什么用处？

Java - 使用数组创建不同的方法

1 个答案: