public class MovingBox extends JFrame
{
    private Rectangle box = new Rectangle(250,300,90,95);
    private  int UP=0,DOWN=1,LEFT=2,RIGHT=3;
    private int boxDirection;
    public MovingBox(){
        super("Moving Box";
        setSize(400,400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        move m1 = new move();
        m1.move();
    }
     public void paint(Graphics g){
      super.paint(g);
      g.setColor(Color.YELLOW);
      g.fillRect(box.x,box.y,box.width,box.height);
      }
      public class move implements KeyListener{
      public void move(){
          addKeyListener(this);
        }
      public void keyPressed(KeyEvent e){}
      public void keyReleased(KeyEvent e){}
      public void keyTyped(KeyEvent e){
        if(e.getKeyChar()=='a')
     {
     boxDirection = LEFT;
     }
     if(e.getKeyChar()=='s')
     {
     boxDirection = DOWN;
     }
    if(e.getKeyChar()=='d')
    {
    boxDirection = RIGHT;
     }
     
     if(e.getKeyChar()=='w')
     {
       boxDirection = UP;
     
     }
    }
}
}

Shimao:

Though there are issues with the structure of your code

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class MovingBox extends JFrame implements ActionListener
{

private boolean isRight = true;
private JButton MoveLeftButton = new JButton("Moving Box Right";
private JButton MoveRightButton = new JButton("Moving Box Left";

public MovingBox()
{
       
     setTitle("Moving Box";
setLayout(new FlowLayout());
add(MoveLeftButton);
add(MoveRightButton);
setSize(500,200);
setLocation(300,300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
MoveRightButton.addActionListener(this);
MoveLeftButton.addActionListener(this);
getContentPane().setBackground(Color.yellow);
setVisible(true);
    }
   
public void paint(Graphics g)
{
super.paint(g);

if(isRight == true)
{
g.drawRect(100,100,90,90);
g.setColor(Color.blue);
g.fillRect(100,100,90,90);
   

}
else
{
g.drawRect(300,100,90,90);
g.setColor(Color.blue);
g.fillRect(300,100,90,90);;
     

}
}

public void actionPerformed(ActionEvent e)
{
if(e.getSource() == MoveRightButton)
{
isRight = true;
repaint();
}

if(e.getSource() == MoveLeftButton)
{
isRight = false;
repaint();
}
}
}

public class runMovingBox {

public static void main(String[] args) {

new MovingBox();
}
}

public class User
{
private static int identifier = 100;
private String userName;
private int storageCapacity = 1000;
private int availableSpace;
private File f;
private String name;
private String date;
private String type;
private String size;
HashMap hm = new HashMap();
Collection c = hm.values();

public User(String userNameIn){
userName = userNameIn;
identifier--;
}
public void addFile(String nameIn, String dateIn, String typeIn, String sizeIn){
name = nameIn;
date = dateIn;
type = typeIn;
size = sizeIn;
f = new File (name, date, type,size);
hm.put(type,f);

}
public void searchFilesByType(String type){
Set<String> theKeys = hm.keySet();
if(theKeys.equals(type)){
System.out.println(hm.get(type));
}


}
public String getUserName(){
return userName;
}

}

public class User
{
private static int identifier = 100;
private String userName;
private int storageCapacity = 1000;
private int availableSpace;
private FileSys f;
private String name;
private String date;
private String type;
private String size;
private Map<String, FileSys>hm;


public User(String userNameIn){
userName = userNameIn;
hm = new HashMap<String, FileSys>();
identifier--;
}
public void addFile(String nameIn, String dateIn, String typeIn, String sizeIn){
name = nameIn;
date = dateIn;
type = typeIn;
size = sizeIn;
f = new FileSys(name, date, type,size);
hm.put(type,f);

}
public void searchFilesByType(String typeIn){
Iterator<String> i = hm.iterator();
while(i.hasNext()){
if(ee.equals(typeIn)) {
System.out.println(hm.get(type));


}
}
}

public String getUserName(){
return userName;
}

}

public void addFile(String nameIn, String dateIn, String typeIn, int sizeIn){
name = nameIn;
date = dateIn;
type = typeIn;
size = sizeIn;
f = new FileSys(name, date, type,size);
totalSize=totalSize+size;
if(availableSpace>0){
availableSpace= storageCapacity-totalSize;
file.add(f);
}
else if(file.contains(nameIn)){
System.out.println("A file with that name already exists";
}
else{
System.out.println("There is no space";
}
}

public void addFile(String nameIn, String dateIn, String typeIn, int sizeIn){
name = nameIn;
date = dateIn;
type = typeIn;
size = sizeIn;
f = new FileSys(name, date, type,size);
totalSize=totalSize+size;
map.put(nameIn,file);
if(availableSpace>0&&!map.containsKey(nameIn)){
availableSpace= storageCapacity-totalSize;
file.add(f);
}
else if(map.containsKey(nameIn)){
System.out.println("A file with that name already exists";
}
else{
System.out.println("There is no space";
}
}

private ArrayList<FileSys>file=new ArrayList<FileSys>();
private Map<String, Collection<FileSys>> map = new HashMap<String, Collection<FileSys>>();

public void addFile(String nameIn, String dateIn, String typeIn, int sizeIn){
name = nameIn;
date = dateIn;
type = typeIn;
size = sizeIn;
f = new FileSys(name, date, type,size);
totalSize=totalSize+size;
map.put(nameIn,file);
if(availableSpace>0&&!map.containsValue(nameIn)){
availableSpace= storageCapacity-totalSize;
file.add(f);
}
else if(map.containsValue(nameIn)){
System.out.println("A file with that name already exists";
}
else{
System.out.println("There is no space";
}
}