How do i fix "Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException"?

Question

Hello I have a little game I made for practice. I am able to put a JLabel on the screen but, when I run the ActionListener actionPerformed third if statement it stops the game. Also i have no idea what to change for the "Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException" Error. Thanks :) Here's the code:

package me.mikail.movement;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.Timer;

public class Player extends JComponent implements ActionListener, KeyListener{

Timer time = new Timer(10, this);
private int x = 0, xSpeed = 3, y = 0, ySpeed = 4, stickX = 0, stickY = 400;
private JFrame frame;
private int oneup = 0;
private JLabel info;

public static void main(String[] args){
    Player p = new Player();
    JFrame frame = new JFrame("Player Practice");
    JLabel info = new JLabel(" ");
    frame.setSize(500,500);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(p);
    frame.getContentPane().setBackground(Color.BLACK);
    frame.setResizable(false);
    frame.addKeyListener(p);
    info.setOpaque(true);
    info.setBackground(Color.WHITE);
    frame.add(info, BorderLayout.SOUTH);
}

public void paintComponent(Graphics g){
    super.paintComponents(g);
    //Ball
    g.setColor(Color.BLUE);
    g.fillRect(x, y, 30, 30);
    //Stick
    g.setColor(Color.RED);
    g.fillRect(stickX, stickY, 75, 10);
    time.start();
}
public void points(){
    int counter[] = {0,1,2,3,4,5,6,7,8,9,10};
    for(int i = 0; i<=oneup; i++){
        info.setText("You have "+counter[i]+" point(s)");
    }
    frame.add(info, BorderLayout.SOUTH);
}
public void actionPerformed(ActionEvent e) {
    //Y's 0 is on the top
    //X's 0  is on the left
    if(x<0){
        xSpeed = -(xSpeed);
    }
    if(x>=470){
        xSpeed = -(xSpeed);
    }
    //when block hits stick
    if(y==stickY){
        if(x>=(stickX)&&x<=(stickX+75)){
            ySpeed = -(ySpeed);
            oneup = (1+oneup);
            points();
        }else{
        }
    }
    if(y<0){
        ySpeed = -(ySpeed);
    }
    if(y>=450){
        ySpeed = -(ySpeed);
    }
    x = (x + xSpeed);
    y = (y + ySpeed);
    repaint();

}

public void keyPressed(KeyEvent e) {
    int key = e.getKeyCode();
    if(key == KeyEvent.VK_A|| key == KeyEvent.VK_LEFT){
        stickX = (stickX - 50);
    }else if(key == KeyEvent.VK_D|| key ==  KeyEvent.VK_RIGHT){
        stickX = (stickX + 50);
    }else{
        System.out.println("Why did you type that?");
    }
}

public void keyReleased(KeyEvent e) {
}

public void keyTyped(KeyEvent e) {
}
}

Hint: you are never assigning anything to the instance fields `frame` and `info`, instead you only assign things to the (static) method local variables with the same names in `main`. — Mark Rotteveel, Dec 12 '15 at 20:35

score 2 · Answer 1 · answered Dec 12 '15 at 18:03

2

for(int i = 0; i<=i; i++){
    info.setText("You have "+counter[i]+" point(s)");
}

- i<=i is always true, no matter the i's value. This for loop will never end...and while doing this, it will probably never get to actually display the text either.

answered Dec 12 '15 at 18:03

Jiri Tousek

12,211
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I changed the for loop to i<1000 but it still doesn't work? The error I'm guessing happens with the third if statement(It doesn't show were the error comes from) – Mikail Dec 12 '15 at 18:10

How do i fix "Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException"?

1 Answers1