Can someone explain why I'm getting this error and how to solve it? Also try to keep it simple. I'm new to coding. (Also i know the answer to the question exists, but i don't know how to implement it to my code)
It gives NullPointerException error when rows are deleted. Also when the blocks move down, the blocks are still counted as 0 so new blocks go through them. (i guess its only the top row, other rows are working as intended) But the actual error is more important: (but i'd be happy if you help to solve this too)
package application;
import java.util.*;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.scene.*;
import javafx.scene.input.*;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.*;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Tetris extends Application {
public static final int MOVE_AMOUNT = 25;
public static final int SIZE = 25;
public static int XLIMIT = SIZE * 10;
public static int YLIMIT = SIZE * 24;
public static int[][] GRID = new int[XLIMIT/SIZE][YLIMIT/SIZE];
private static Pane group = new Pane();
private static Shape object;
private static Scene scene = new Scene(group, XLIMIT, YLIMIT);
public static void main(String[] args) { launch(args); }
@Override public void start(Stage stage) throws Exception {
for(int[] a: GRID){
Arrays.fill(a, 0);
}
for(int i = 0; i <= XLIMIT; i+= SIZE){
Line a = new Line(i, 0, i, YLIMIT);
group.getChildren().add(a);
}
for(int i = 0; i <= YLIMIT; i+= SIZE){
Line a = new Line(0, i, XLIMIT, i);
group.getChildren().add(a);
}
for(int i = 0; i <= YLIMIT; i+= SIZE){
Text a = new Text("" + i);
a.setY(i);
group.getChildren().add(a);
}
for(int i = SIZE; i < XLIMIT; i+= SIZE){
Text a = new Text("" + i);
a.setY(10);
a.setX(i);
group.getChildren().add(a);
}
Shape a = TetrisHolder.createRect();
group.getChildren().addAll(a.a, a.b, a.c, a.d);
moveOnKeyPress(scene, a.a, a.b, a.c, a.d);
object = a;
stage.setScene(scene);
stage.show();
Timer myTimer=new Timer();
TimerTask task =new TimerTask() {
@Override
public void run() {
Platform.runLater(new Runnable(){
public void run(){
CheckDown(object);
}
});
}
};
myTimer.schedule(task,0,300);
}
private void moveOnKeyPress(Scene scene, Rectangle rect, Rectangle rect2, Rectangle rect3, Rectangle rect4) {
scene.setOnKeyPressed(new EventHandler<KeyEvent>() {
@Override public void handle(KeyEvent event) {
Shape shape = new Shape(rect, rect2, rect3, rect4);
switch (event.getCode()) {
case RIGHT:
TetrisHolder.CheckRight(shape);
break;
case DOWN:
CheckDown(shape);
break;
case LEFT:
TetrisHolder.CheckLeft(shape);
break;
case UP:
//TetrisHolder.CheckTurn(shape);
break;
}
}
});
}
private void CheckTurn(Shape shape){
}
private void DeleteRows(Pane pane){
ArrayList<Node> rects = new ArrayList<Node>();
ArrayList<Integer> lines = new ArrayList<Integer>();
int full = 0;
for(int i = 0; i < GRID[0].length; i++){
for(int j = 0; j < GRID.length; j++){
if(GRID[j][i] == 1)
full++;
}
if(full == GRID.length)
lines.add(i/*+lines.size()*/);
full = 0;
}
for(Node node: pane.getChildren()) {
if(node instanceof Rectangle) {
rects.add(node);
}
}
if(lines.size() > 0)
do{
for(Node node: rects){
Rectangle a = (Rectangle)node;
if(a.getY() == lines.get(0)*SIZE){
GRID[(int)a.getX()/SIZE][(int)a.getY()/SIZE] = 0;
pane.getChildren().remove(node);
}
if(a.getY() < lines.get(0)*SIZE){
GRID[(int)a.getX()/SIZE][(int)a.getY()/SIZE] = 0;
a.setY(a.getY() + SIZE);
GRID[(int)a.getX()/SIZE][(int)a.getY()/SIZE] = 1;
}
}
lines.remove(0);
rects.clear();
for(Node node: pane.getChildren()) {
if(node instanceof Rectangle) {
rects.add(node);
}
}
} while(lines.size() > 0);
}
private void CheckDown(Shape shape){
if((shape.c.getY() == YLIMIT - SIZE) || checkA(shape) || checkB(shape) || checkC(shape) || checkD(shape)){
GRID[(int)shape.a.getX()/SIZE][(int)shape.a.getY()/SIZE] = 1;
GRID[(int)shape.b.getX()/SIZE][(int)shape.b.getY()/SIZE] = 1;
GRID[(int)shape.c.getX()/SIZE][(int)shape.c.getY()/SIZE] = 1;
GRID[(int)shape.d.getX()/SIZE][(int)shape.d.getY()/SIZE] = 1;
DeleteRows(group);
Shape a = TetrisHolder.createRect();
object = a;
group.getChildren().addAll(a.a, a.b, a.c, a.d);
moveOnKeyPress(shape.a.getScene(), a.a, a.b, a.c, a.d);
}
if(shape.c.getY() + MOVE_AMOUNT < YLIMIT){
int checka = GRID[(int)shape.a.getX()/SIZE][((int)shape.a.getY()/SIZE) + 1];
int checkb = GRID[(int)shape.b.getX()/SIZE][((int)shape.b.getY()/SIZE) + 1];
int checkc = GRID[(int)shape.c.getX()/SIZE][((int)shape.c.getY()/SIZE) + 1];
int checkd = GRID[(int)shape.d.getX()/SIZE][((int)shape.d.getY()/SIZE) + 1];
if(checka == 0 && checka == checkb && checkb == checkc && checkc == checkd){
shape.a.setY(shape.a.getY() + MOVE_AMOUNT);
shape.b.setY(shape.b.getY() + MOVE_AMOUNT);
shape.c.setY(shape.c.getY() + MOVE_AMOUNT);
shape.d.setY(shape.d.getY() + MOVE_AMOUNT);
}
}
}
private boolean checkA(Shape shape){
return (GRID[(int)shape.a.getX()/SIZE][((int)shape.a.getY()/SIZE) + 1] == 1);
}
private boolean checkB(Shape shape){
return (GRID[(int)shape.b.getX()/SIZE][((int)shape.b.getY()/SIZE) + 1] == 1);
}
private boolean checkC(Shape shape){
return (GRID[(int)shape.c.getX()/SIZE][((int)shape.c.getY()/SIZE) + 1] == 1);
}
private boolean checkD(Shape shape){
return (GRID[(int)shape.d.getX()/SIZE][((int)shape.d.getY()/SIZE) + 1] == 1);
}
}
The error:
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at application.Tetris.moveOnKeyPress(Tetris.java:70)
at application.Tetris.CheckDown(Tetris.java:147)
at application.Tetris.access$1(Tetris.java:137)
at application.Tetris$1$1.run(Tetris.java:60)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
