Calculate the median in an array

Question

I am doing an assignment in Java about this: Have the function ArrayChallenge(arr) read the array of numbers stored in arr which will contain a sliding window size, N, as the first element in the array and the rest will be a list of numbers. Your program should return the Moving Median for each element based on the element and its N-1 predecessors, where N is the sliding window size. The final output should be a string with the moving median corresponding to each entry in the original array separated by commas.

this is the code that I wrote:

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.*;
import java.awt.event.*;
import org.apache.commons.math3.*;

public class whileloopq extends Applet implements ActionListener
{

Label label;
TextField input;
int num;
int index;
int[] numArray = new int[20];
int sum;
int total;
double avg;
int median;

public void init()
{
 label = new Label("Enter numbers:");
 input = new TextField(5);
 add(label);
 add(input);
 input.addActionListener(this);
  index = 0;
  }

public void actionPerformed(ActionEvent ev)
  {
  int num = Integer.parseInt(input.getText());
  numArray[index] = num;
  index++;
  if (index == 20)
    input.setEnabled(false);
    input.setText("");
    sum = 0;
    for (int i = 0; i < numArray.length; i++)
    {
      sum += numArray[i];
    }
    total = sum;
    avg = total / index;
    median = numArray[numArray.length/2];

    repaint();
  }

  public void paint(Graphics graf)
  {
    graf.drawString("Total = "+ Integer.toString(total), 25, 85);
    graf.drawString("Average ="+ Double.toString(avg), 25, 100);
    graf.drawString("Median ="+ Integer.toString(median), 25, 115)
  }

}

This is the error that shows up:

/tmp/560075432/main.js:1
import java.applet.Applet;
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at wrapSafe (internal/modules/cjs/loader.js:1072:16)
    at Module._compile (internal/modules/cjs/loader.js:1122:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1178:10)
    at Module.load (internal/modules/cjs/loader.js:1002:32)
    at Function.Module._load (internal/modules/cjs/loader.js:901:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:74:12)
    at internal/main/run_main_module.js:18:47

I don't understand what is the problem with this