java.lang.NullPointerException

**peterhabe** · 08-27-2010, 08:19 PM

Here is the long error message I get when I run the program:

Java Code:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at projectileProgram.DrawingGraphsThread.<init>(DrawingGraphsThread.java:19)
	at projectileProgram.ControlPanelJPanel.actionPerformed(ControlPanelJPanel.java:318)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

Im out of ideas of that is causing the error so can someone help?

Here are the classes with the errors. I've clearly marked where the error occur.

Java Code:

package projectileProgram;

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

public class ControlPanelJPanel extends JPanel implements ChangeListener, ActionListener, ItemListener{
	//variables
	double milliseconds, horizontalVelocity, verticalVelocity, timePassed;
	long wholeNumber;
	//Class Objects
	ProjectileAnimationJPanel projectileAnimationJPanel;
	TimeSpeedGraphJPanel timeSpeedGraphJPanel;
	HorizontalVelocityGraphJPanel horizontalVelocityGraphJPanel;
	VerticalVelocityGraphJPanel verticalVelocityGraphJPanel;
	ControlPanelJPanel controlPanelJPanel;
	//setting JSliders
	JSlider height = new JSlider(0,50,50);
    JSlider angle = new JSlider(0,90,0);
    JSlider speed = new JSlider(0,50,50);
    JButton start, reset;
    JCheckBox timeSpeedGraph, verticalVelocityGraph, horozontalVelocityGraph;
    JLabel heightValues, angleValues, speedValues, time;
    //setting variables elevation, projectionAngle and projectionSpeed
    String heightValue = String.valueOf(height.getValue());
    String angleValue = String.valueOf(angle.getValue());
    String speedValue = String.valueOf(speed.getValue());
    String timePassedString = "0.000";
    //setting JSlider values
    float elevation = Float.parseFloat(heightValue);
	float projectionAngle = Float.parseFloat(angleValue);
	float projectionSpeed = Float.parseFloat(speedValue);
    //constructor
	public ControlPanelJPanel(){
		//height JSlider
		height.setMajorTickSpacing(10);
		height.setMinorTickSpacing(1);
		height.setPaintTicks(true);
		height.setPaintLabels(true);
		height.setOpaque(false);
		height.addChangeListener(this);
		
		//Angle JSlider 
		angle.setMajorTickSpacing(10);
		angle.setMinorTickSpacing(1);
		angle.setPaintTicks(true);
		angle.setPaintLabels(true);
		angle.setOpaque(false);
		angle.addChangeListener(this);
		
		//Speed JSlider 
		speed.setMajorTickSpacing(10);
		speed.setMinorTickSpacing(1);
		speed.setPaintTicks(true);
		speed.setPaintLabels(true);
		speed.setOpaque(false);
		speed.addChangeListener(this);
		
		//setting time JLabel
		time = new JLabel("Time/s: "+timePassedString);
		
		//creating labels for Sliders	
		JLabel heightLabel = new JLabel	("Height: ");
        JLabel angleLabel = new JLabel ("Angle: ");
        JLabel speedLabel = new JLabel ("Speed: ");
        
        //creating labels for value of sliders
        heightValues = new JLabel("Height Value: "+heightValue);
        angleValues = new JLabel ("Angle Value: "+angleValue);
        speedValues = new JLabel ("Speed Value: "+speedValue);
        
        //start button
        start = new JButton("start");
        start.setPreferredSize(new Dimension(75,25));
        start.addActionListener(this);
        
        //reset button
        reset = new JButton("reset");
        reset.setPreferredSize(new Dimension(75,25));
        reset.addActionListener(this);
        
        
        //setting JCheckBoxes
        JCheckBox timeSpeedGraph = new JCheckBox("Time Speed Graph");
        timeSpeedGraph.setOpaque(false);
        timeSpeedGraph.addItemListener(this);
        
        JCheckBox verticalVelocityGraph = new JCheckBox("Vertical Velocity Graph");
        verticalVelocityGraph.setOpaque(false);
        verticalVelocityGraph.addItemListener(this);
        
        JCheckBox horozontalVelocityGraph = new JCheckBox("Horozontal Velocity Graph");
        horozontalVelocityGraph.setOpaque(false);
        horozontalVelocityGraph.addItemListener(this);
        
        //setting layout
        this.setLayout(new GridBagLayout());
        GridBagConstraints gc = new GridBagConstraints(); 
        
        //column 0
        gc.weightx = 25;
		gc.weighty = 100;
        //adding start to screen 
		gc.gridx = 0;
		gc.gridy = 1;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.NONE;
		add(start, gc);
		
		//adding reset to screen 
		gc.gridx = 0;
		gc.gridy = 2;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.NONE;
		add(reset, gc);
		
		//adding timePassed
		gc.gridx = 0;
		gc.gridy = 6;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.NONE;
		add(time, gc);
        
		//column 1
		gc.weightx = 25;
		gc.weighty = 100;
		//adding heightLabel to screen 
		gc.gridx = 1;
		gc.gridy = 1;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.EAST;
		gc.fill = GridBagConstraints.NONE;
		add(heightLabel, gc);
		
		//column 2
		gc.weightx = 100;
		gc.weighty = 100;
		//adding height to screen
		gc.gridx = 2;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(height, gc);
		
		//adding heightValues to screen
		gc.gridx = 2;
		gc.gridy = 3;
		gc.gridwidth = 2;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(heightValues, gc);
		
		//column 3
		gc.weightx = 25;
		gc.weighty = 100;
		//adding angleLabel to screen
		gc.gridx = 3;
		gc.gridy = 1;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.EAST;
		gc.fill = GridBagConstraints.NONE;
		add(angleLabel, gc);
		
		//column 4
		gc.weightx = 100;
		gc.weighty = 100;
		//adding speed angle to screen
		gc.gridx = 4;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(angle, gc);
		
		//adding angleValues to screen
		gc.gridx = 4;
		gc.gridy = 3;
		gc.gridwidth = 2;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(angleValues, gc);
		
		//column 5
		gc.weightx = 25;
		gc.weighty = 100;
		//adding speedLabel to screen
		gc.gridx = 5;
		gc.gridy = 1;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.EAST;
		gc.fill = GridBagConstraints.NONE;
		add(speedLabel, gc);
		
		//column 6
		gc.weightx = 100;
		gc.weighty = 100;
		//adding speed to screen
		gc.gridx = 6;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(speed, gc);
		
		//adding speedValues to screen
		gc.gridx = 6;
		gc.gridy = 3;
		gc.gridwidth = 2;
		gc.gridheight = 3;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(speedValues, gc);
		
		//column 7
		gc.weightx = 100;
		gc.weighty = 100;
		//adding timeSpeedGraph to screen
		gc.gridx = 7;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 2;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(timeSpeedGraph, gc);
		
		//adding horozontalVelocityGraph to screen
		gc.gridx = 7;
		gc.gridy = 2;
		gc.gridwidth = 1;
		gc.gridheight = 2;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(horozontalVelocityGraph, gc);
		
		
		//adding verticalVelocityGraph to screen
		gc.gridx = 7;
		gc.gridy = 4;
		gc.gridwidth = 1;
		gc.gridheight = 2;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		add(verticalVelocityGraph, gc);
	}
	//paint method
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.GREEN);
	}
	//returning elevation method
	public float getElevation(){
		return elevation;
	}
	public float getAngle(){
		return projectionAngle;
	}
	public float getProjectionSpeed(){
		return projectionSpeed;
	}
	//state listener
	public void stateChanged(ChangeEvent event) {
		JSlider source = (JSlider) event.getSource();
		
		//setting elevation/projectionAngle or projectionSpeed value to new JSlider Value
		if(source.getValueIsAdjusting() != true){
			if(event.getSource() == height){
				heightValue = String.valueOf(height.getValue());
				elevation = Float.parseFloat(heightValue);
				heightValues.setText("Height Value: "+heightValue);
			}else if(event.getSource() == angle){
				angleValue = String.valueOf(angle.getValue());
				projectionAngle = Float.parseFloat(angleValue);
				angleValues.setText("Angle Value: "+angleValue);
			}else if(event.getSource() == speed){
				speedValue = String.valueOf(speed.getValue());
			 	projectionSpeed = Float.parseFloat(speedValue);
			 	speedValues.setText("Speed Value: "+speedValue);
			 }
		}
	}
	//action listener
	public void actionPerformed(ActionEvent event){
		if(event.getSource().equals(start)){
			Thread animationThread = new Thread(new AnimationThread(projectileAnimationJPanel, controlPanelJPanel, projectileAnimationJPanel.getElevation(), getAngle(), getProjectionSpeed(), projectileAnimationJPanel.getWidth(), projectileAnimationJPanel.getHeight(), projectileAnimationJPanel.getSizeOfMeter()));
			animationThread.start();

/////////////////////////////////////////////////////at projectileProgram.ControlPanelJPanel.actionPerformed(ControlPanelJPanel.java:318)//////////////////////////////////////////////////
			Thread drawingGraphsThread = new Thread(new DrawingGraphsThread(timeSpeedGraphJPanel, horizontalVelocityGraphJPanel, verticalVelocityGraphJPanel, controlPanelJPanel, getAngle(), getProjectionSpeed()));
			drawingGraphsThread.start();
			timeSpeedGraphJPanel.settingBooleanRunning(true);
		}else if(event.getSource().equals(reset)){
			timePassedString = "0.000";
			projectileAnimationJPanel.settingXAndYStartingPosition();
			time.setText("Time/s: "+timePassedString);
		}
	}
	//item listener
	public void itemStateChanged(ItemEvent event){
		
	}
	//setting values from ProjectileAnimationJPanel
	public void settingValues(ProjectileAnimationJPanel p, TimeSpeedGraphJPanel t, HorizontalVelocityGraphJPanel hv, VerticalVelocityGraphJPanel vv, ControlPanelJPanel c){
		projectileAnimationJPanel = p;
		timeSpeedGraphJPanel = t;
		horizontalVelocityGraphJPanel = hv;
		verticalVelocityGraphJPanel = vv;
		controlPanelJPanel = c;
	}
	//setting JLabel time
	public void settingJLabelTime(double t, double hv, double vv){
		//setting variables
		milliseconds = t/1000;
		horizontalVelocity = hv;
		verticalVelocity = vv;
		timePassed = t;
		
		//setting whole number
		if(milliseconds<1)
			wholeNumber = 0;
		else
			wholeNumber = Math.round(Math.floor(milliseconds));
		
		timePassedString = String.format("%s.%03d", wholeNumber, Math.round(t)-wholeNumber*1000);
		time.setText("Time/s: "+timePassedString);
	}
	//return time passed since beginning of animation loop
	public double getTimePassed(){
		return timePassed;
	}
	//return horizontal velocity
	public double getHoriontalVelocity(){
		return horizontalVelocity;
	}
	//return vertical velocity
	public double getVerticalVelocity(){
		return verticalVelocity;
	}
}

Java Code:

package projectileProgram;

public class DrawingGraphsThread implements Runnable{
	//variables
	TimeSpeedGraphJPanel timeSpeedGraphJPanel;
	HorizontalVelocityGraphJPanel horizontalVelocityGraphJPanel;
	VerticalVelocityGraphJPanel verticalVelocityGraphJPanel;
	ControlPanelJPanel controlPanelJPanel;
	double horizontalVelocity[], verticalVelocity[], timePassed[], speed[], angle;
	int loopCounter;
	//constructor
	public DrawingGraphsThread(TimeSpeedGraphJPanel t, HorizontalVelocityGraphJPanel h, VerticalVelocityGraphJPanel v, ControlPanelJPanel c,float a, float s){
		//setting variables
		timeSpeedGraphJPanel = t;
		horizontalVelocityGraphJPanel = h;
		verticalVelocityGraphJPanel = v;
		controlPanelJPanel = c;
		angle = Double.parseDouble(String.valueOf(a));

////////////////////////////////////////////at projectileProgram.DrawingGraphsThread.<init>(DrawingGraphsThread.java:19)///////////////////////////////////////////////////
		speed[0] = Double.parseDouble(String.valueOf(s));
		horizontalVelocity[0] = s*Math.abs(Math.cos(Math.toRadians(angle)));
		verticalVelocity[0] = s*Math.sin(Math.toRadians(angle));
		timePassed[0] = 0;
		loopCounter = 1;
	}
	//run method
	public void run(){
		//loop
		do{
			try{
				Thread.sleep(10);
			}catch(Exception e){};
			
			horizontalVelocity[loopCounter] = controlPanelJPanel.getHoriontalVelocity();
			verticalVelocity[loopCounter] = controlPanelJPanel.getVerticalVelocity();
			speed[loopCounter] = horizontalVelocity[loopCounter]/Math.abs(Math.cos(Math.toRadians(angle)));
			timePassed[loopCounter] = controlPanelJPanel.getTimePassed();
			
			//setting values in classes
			timeSpeedGraphJPanel.settingTime(timePassed[loopCounter]);
			
			
			//incrementing loopCounter
			loopCounter++;
		}while(timePassed[loopCounter]!=timePassed[loopCounter-1]);
		timeSpeedGraphJPanel.settingBooleanRunning(false);
	}
}

And here are the rest of the many classes of this program:

Java Code:

package projectileProgram;

import javax.swing.JFrame;

public class Run {
	public static void main(String args[]){
		ProjectileProgramFixedSize runProgram = new ProjectileProgramFixedSize();

		runProgram.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		//setting frame
		runProgram.setSize(1920,1080);
		runProgram.setResizable(false);
		runProgram.setVisible(true);
	}
}

Java Code:

package projectileProgram;

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

public class ProjectileProgramFixedSize extends JFrame{
	//class objects
	ProjectileAnimationJPanel projectileAnimationJPanel = new ProjectileAnimationJPanel();
	ControlPanelJPanel controlPanelJPanel = new ControlPanelJPanel();
	TimeSpeedGraphJPanel timeSpeedGraphJPanel = new TimeSpeedGraphJPanel(controlPanelJPanel);
	HorizontalVelocityGraphJPanel horizontalVelocityGraphJPanel = new HorizontalVelocityGraphJPanel();
	VerticalVelocityGraphJPanel verticalVelocityGraphJPanel = new VerticalVelocityGraphJPanel();
	//variables
	JScrollPane timeSpeedGraphJScrollPane = new JScrollPane(timeSpeedGraphJPanel);
	JScrollPane horizontalVelocityGraphJScrollPane = new JScrollPane(horizontalVelocityGraphJPanel);
	JScrollPane verticalVelocityGraphJScrollPane = new JScrollPane(verticalVelocityGraphJPanel);
	
	//constructor
	public ProjectileProgramFixedSize(){
		super("Projectile Program");
		setLayout(new GridBagLayout());
		
		//setting layout
		GridBagConstraints gc = new GridBagConstraints();
		gc.gridx = 0;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 3;
		gc.weightx = 100;
		gc.weighty = 100;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		this.add(projectileAnimationJPanel, gc);
		
		gc.gridx = 1;
		gc.gridy = 0;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.weightx = 50;
		gc.weighty = 50;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		this.add(timeSpeedGraphJScrollPane, gc);
		
		gc.gridx = 1;
		gc.gridy = 1;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		this.add(horizontalVelocityGraphJScrollPane, gc);

		gc.gridx = 1;
		gc.gridy = 2;
		gc.gridwidth = 1;
		gc.gridheight = 1;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		this.add(verticalVelocityGraphJScrollPane, gc);
		
		gc.gridx = 0;
		gc.gridy = 3;
		gc.gridwidth = 2;
		gc.gridheight = 1;
		gc.weighty = 5;
		gc.insets = new Insets(5,5,5,5);
		gc.anchor = GridBagConstraints.CENTER;
		gc.fill = GridBagConstraints.BOTH;
		this.add(controlPanelJPanel, gc);
		
		settingVariablesForOtherClasses();
	}
	public void settingVariablesForOtherClasses(){
		//creating thread to set elevation
		Thread settingElevationThread = new Thread(new SettingElevationThread(controlPanelJPanel, projectileAnimationJPanel));
		settingElevationThread.start();
		
		//setting x and y positions in ProjectileAnimationJPanel class on first run
		projectileAnimationJPanel.settingXAndYPosisions(projectileAnimationJPanel.getWidth()/20-projectileAnimationJPanel.getHeight()/40, projectileAnimationJPanel.getHeight()-controlPanelJPanel.getElevation()-projectileAnimationJPanel.getHeight()/8-projectileAnimationJPanel.getHeight()/20);
		
		//giving actionPerformed() in ControlPanelJPanel class the variables needed to start and run threads
		controlPanelJPanel.settingValues(projectileAnimationJPanel, timeSpeedGraphJPanel, horizontalVelocityGraphJPanel, verticalVelocityGraphJPanel, controlPanelJPanel);
		
		//starting repaint thread
		Thread repaintThread = new Thread(new RepaintThread(projectileAnimationJPanel, timeSpeedGraphJPanel, horizontalVelocityGraphJPanel, verticalVelocityGraphJPanel, controlPanelJPanel));
		repaintThread.start();
	}
}

Java Code:

package projectileProgram;

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

public class ProjectileAnimationJPanel extends JPanel{
	//variables
	float elevationDP, meter;
	int elevation, previousElevation, xPosition, yPosition;
	int i = 0;
	boolean run = false;
	//paint method
	public void paintComponent(Graphics g){
		Graphics2D g2 = (Graphics2D)g;
		super.paintComponent(g2);
		this.setBackground(Color.BLUE);
		
		//adding anti-aliasing
		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		
		//drawing elevation
		g2.setColor(Color.GREEN);
		g2.fillRect(0, getHeight()-elevation-(this.getHeight()/8),this.getWidth()/20 , elevation);
		
		//drawing ground
		g2.setColor(Color.GREEN);
		g2.fillRect(0, 7*getHeight()/8, getWidth(), getHeight()/8+1);
		
		//drawing ball
		g2.setColor(Color.RED);
		g2.fillOval(xPosition, yPosition, getHeight()/20, getHeight()/20);
				
		//drawing black lines
		g2.setColor(Color.BLACK);
		//drawing on ground
		g2.drawLine(getWidth()/20, 7*getHeight()/8, getWidth(), 7*getHeight()/8);
		//drawing line on top of elevation
		g2.drawLine(0, 7*getHeight()/8-elevation, getWidth()/20, 7*getHeight()/8-elevation);
		//drawing line at side of elevation
		g2.drawLine(getWidth()/20, 7*getHeight()/8-elevation, getWidth()/20, 7*getHeight()/8);
	}
	public void setElevation(float e){
		elevationDP = (getWidth()*(e/50))/8;
		elevation = Math.round(elevationDP);
		
		//testing for change in elevation
		if(previousElevation != elevation){
			//setting height ball to new elevation
			settingXAndYStartingPosition();
			
			//setting previousElevation to new elevation
			previousElevation = elevation;
		}
	}
	public float getSizeOfMeter(){
		meter = Float.parseFloat(String.valueOf((getWidth())));
		return meter/400;
	}
	public float getElevation(){
		return elevation;
	}
	public void settingXAndYPosisions(double x, double y){
		xPosition = Math.round(Float.parseFloat(String.valueOf(x)));
		yPosition = Math.round(Float.parseFloat(String.valueOf(y)));
	}
	public void settingXAndYStartingPosition(){
		xPosition = getWidth()/20-getHeight()/40;
		yPosition = 7*getHeight()/8-elevation-getHeight()/20;
	}
}

Java Code:

package projectileProgram;

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

public class TimeSpeedGraphJPanel extends JPanel{
	//variables 
	int[] speed, time;
	int counter = 0;
	boolean running = false;
	ControlPanelJPanel controlPanelJPanel;
	//constructor
	public TimeSpeedGraphJPanel(ControlPanelJPanel c){
		controlPanelJPanel = c;
	}
	//paint method
	public void paintComponent(Graphics g){
		//housekeeping
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
		Graphics2D g2 = (Graphics2D)g;
		//variables
		int counterVScale = 10;
		int counterHScale = 5;
		
		g2.setColor(Color.LIGHT_GRAY);

		//vertical lines
		for(int i = 30;i < getWidth(); i += 10){
			g2.drawLine(i, 0, i, getHeight()-25);
			
			//x axis values
			if(counterVScale == 10){
				g2.drawString(String.valueOf(i/100), i-3, getHeight()-12);
				counterVScale = 0;
			}
			counterVScale++;
		}
		//horizontal lines
		for(int i = 25;i < getHeight(); i += 10){
			g2.drawLine(30, getHeight()-i, getWidth(), getHeight()-i);
			
			//y axis values
			if(counterHScale == 5){
				g2.drawString(String.valueOf(i/5-5), 15, getHeight()-i+5);
				counterHScale = 0;
			}
			counterHScale++;
		}
		
		//drawing x axis label
		g2.drawString("Time/s", getWidth()/2-15, getHeight()-1);
		//drawing y axis label
		g2.rotate(Math.toRadians(90), 1, getHeight()/2);
		g2.drawString("Speed m/s", -25, getHeight()/2);	
		
		//drawing line graph
		if(running == true){
			for(int c = 0; c<= time.length; c++){
				g.drawLine(time[counter-1], speed[counter-1], time[counter], speed[counter]);
			};
		}
	}
	public void settingTime(double t){
		time[counter] = Math.round(Float.parseFloat(String.valueOf(t)));
	}
	public void settingSpeed(double s){
		speed[counter] = Math.round(Float.parseFloat(String.valueOf(s)));
	}
	public void settingBooleanRunning(boolean r){
		running = r;
	}
}

Java Code:

package projectileProgram;

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

public class HorizontalVelocityGraphJPanel extends JPanel{
	//paint method
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
		Graphics2D g2 = (Graphics2D)g;
		//variables
		int counterVScale = 10;
		int counterHScale = 5;
		
		g2.setColor(Color.LIGHT_GRAY);

		//vertical lines
		for(int i = 30;i < getWidth(); i += 10){
			g2.drawLine(i, 0, i, getHeight()-25);
			
			//x axis values
			if(counterVScale == 10){
				g2.drawString(String.valueOf(i/100), i-3, getHeight()-12);
				counterVScale = 0;
			}
			counterVScale++;
		}
		//horizontal lines
		for(int i = 25;i < getHeight(); i += 10){
			g2.drawLine(30, getHeight()-i, getWidth(), getHeight()-i);
			
			//y axis values
			if(counterHScale == 5){
				g2.drawString(String.valueOf(i/5-5), 15, getHeight()-i+5);
				counterHScale = 0;
			}
			counterHScale++;
		}
		
		//drawing x axis label
		g2.drawString("Time/s", getWidth()/2-15, getHeight()-1);
		//drawing y axis label
		g2.rotate(Math.toRadians(90), 1, getHeight()/2);
		g2.drawString("Horizontal Speed m/s", -60, getHeight()/2);
	}
}

Java Code:

package projectileProgram;

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

public class VerticalVelocityGraphJPanel extends JPanel{
	//paint method
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
		Graphics2D g2 = (Graphics2D)g;
		//variables
		int counterVScale = 10;
		int counterHScale = 5;
		
		g2.setColor(Color.LIGHT_GRAY);

		//vertical lines
		for(int i = 30;i < getWidth(); i += 10){
			g2.drawLine(i, 0, i, getHeight()-25);
			
			//x axis values
			if(counterVScale == 10){
				g2.drawString(String.valueOf(i/100), i-3, getHeight()-12);
				counterVScale = 0;
			}
			counterVScale++;
		}
		//horizontal lines
		for(int i = 25;i < getHeight(); i += 10){
			g2.drawLine(30, getHeight()-i, getWidth(), getHeight()-i);
			
			//y axis values
			if(counterHScale == 5){
				g2.drawString(String.valueOf(i/5-5), 15, getHeight()-i+5);
				counterHScale = 0;
			}
			counterHScale++;
		}
		
		//drawing x axis label
		g2.drawString("Time/s", getWidth()/2-15, getHeight()-1);
		//drawing y axis label
		g2.rotate(Math.toRadians(90), 1, getHeight()/2);
		g2.drawString("Vertical Speed m/s", -50, getHeight()/2);	
	}
	public void setPointsMethod(double x, double y, int c){
		
	}
}

Java Code:

package projectileProgram;

import javax.swing.JPanel;

public class AnimationThread implements Runnable{
	//variables
	ProjectileAnimationJPanel projectileAnimationJPanel;
	ControlPanelJPanel controlPanelJPanel;
	JPanel panel = new JPanel();
	double elevation, projectionAngle, projectionSpeed,  xVelocity, yVelocity, xPosition, yPosition, height, width, startTime, timeOfLastRun, timeBetweenRuns, meter;
	double timePassed = 0;
	//constructor 
	public AnimationThread(ProjectileAnimationJPanel p, ControlPanelJPanel c, float e, float a, float s, int w, int h, float m){	
		projectileAnimationJPanel = p;
		controlPanelJPanel = c;
		
		//converting numbers to strings then to doubles
		meter = Double.parseDouble(String.valueOf(m));
		elevation = Double.parseDouble(String.valueOf(e));
		projectionAngle = Double.parseDouble(String.valueOf(a));
		projectionSpeed = Double.parseDouble(String.valueOf(s))*meter;
		width = Double.parseDouble(String.valueOf(w));
		height = Double.parseDouble(String.valueOf(h));
		
		//finding horizontal and vertical velocities
		xVelocity = projectionSpeed*Math.abs(Math.cos(Math.toRadians(projectionAngle)));
		yVelocity = -projectionSpeed*Math.sin(Math.toRadians(projectionAngle));
		
		//setting starting positions
		xPosition = width/20-height/40;
		yPosition = 7*height/8-elevation-height/20;
	}
	public void run(){
		//setting startTime
		startTime = System.currentTimeMillis();	
		
		//loop
		do{
			//making thread sleep
			try{
				Thread.sleep(1);
			}catch(Exception e){}
			
			//setting time
			timeOfLastRun = timePassed;
			timePassed = System.currentTimeMillis()- startTime;
			timeBetweenRuns = timePassed - timeOfLastRun;
			
			//changing position
			xPosition += xVelocity*timeBetweenRuns/1000;
			yVelocity += 9.8*meter*timeBetweenRuns/1000;
			yPosition += yVelocity*timeBetweenRuns/1000;
			
			//setting x and y positions in ProjectileAnimationJPanel class
			projectileAnimationJPanel.settingXAndYPosisions(xPosition, yPosition);
			//setting time JLabel in controlPanel class
			controlPanelJPanel.settingJLabelTime(timePassed, xVelocity, yVelocity);
		}while(yPosition<7*height/8-height/20);
	}
}

Java Code:

package projectileProgram;

public class RepaintThread implements Runnable{
	//variables
	ProjectileAnimationJPanel projectileAnimationJPanel;
	TimeSpeedGraphJPanel timeSpeedGraphJPanel;
	HorizontalVelocityGraphJPanel horizontalVelocityGraphJPanel;
	VerticalVelocityGraphJPanel verticalVelocityGraphJPanel;
	ControlPanelJPanel controlPanelJPanel;
	//constructor
	public RepaintThread(ProjectileAnimationJPanel p, TimeSpeedGraphJPanel t, HorizontalVelocityGraphJPanel h, VerticalVelocityGraphJPanel v, ControlPanelJPanel c){
		projectileAnimationJPanel = p;
		timeSpeedGraphJPanel = t;
		horizontalVelocityGraphJPanel = h;
		verticalVelocityGraphJPanel = v;
		controlPanelJPanel = c;
	}
	//run method
	public void run(){
		for(int i = 0;i >= 0; i++){
			//making thread sleep
			try{
				Thread.sleep(10);
			}catch(Exception e){}
			
			//calling repaint methods
			projectileAnimationJPanel.repaint();
			timeSpeedGraphJPanel.repaint();
			horizontalVelocityGraphJPanel.repaint();
			verticalVelocityGraphJPanel.repaint();
		}
	}
}

**Norm** · 08-27-2010, 08:27 PM

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at projectileProgram.DrawingGraphsThread.<init>(Drawi ngGraphsThread.java:19)

Look at line 19 in DrawingGraphsThread.
What variable on that line is null? Then track back thru your code to see why it is null.

**JosAH** · 08-27-2010, 08:32 PM

Originally Posted by Norm

Look at line 19 in DrawingGraphsThread.
What variable on that line is null? Then track back thru your code to see why it is null.

My guess: the speed[] array is null. (and there are more things not initialized).

kind regards,

Jos

**peterhabe** · 08-27-2010, 08:32 PM

I've tried but if I put

Java Code:

System.out.println(Double.parseDouble(String.valueOf(s)));

, which is what the value on line 19 been set to, on the line before it comes out with a value.

**peterhabe** · 08-27-2010, 08:39 PM

JosAH looks like you guessed right.:p cheers

**JosAH** · 08-27-2010, 08:43 PM

Originally Posted by peterhabe

JosAH looks like you guessed right.:p cheers

1) I'm always right.
2) unless I'm wrong but then rule 1) applies.

kind regards,

Jos ;-)

Thread: java.lang.NullPointerException

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