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POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
 

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  1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
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    <p>I have got this exercise working perfectly:</p> <pre><code>import acm.program.*; import acm.graphics.*; import java.awt.event.*; public class ProgramHierarchy extends GraphicsProgram { public void run() { Paddle = new GRect(0,getHeight() - 30,100,20); add(Paddle); addMouseListeners(); } public void mouseMoved(MouseEvent e) { if(e.getX() - Paddle.getWidth()&gt;0) { Paddle.move(e.getX()-Paddle.getX()-Paddle.getWidth(), 0); } } private GRect Paddle; } </code></pre> <p>But when I use the <strong>exact same code</strong> in a larger project, my eclipse throws null pointer exceptions and even hard-crashes eclipse altogether and I hit my desk and say bad things I would not like my family to hear. Is my copy of eclipse corrupt? What could be going on?</p> <p>Here's my larger hard-crashing project.</p> <pre><code>import acm.graphics.*; import acm.program.*; import acm.util.*; import java.applet.*; import java.awt.*; import java.awt.event.*; public class Breakout extends GraphicsProgram { public static final int APPLICATION_WIDTH = 400; public static final int APPLICATION_HEIGHT = 600; private static final int WIDTH = APPLICATION_WIDTH; private static final int HEIGHT = APPLICATION_HEIGHT; private static final int PADDLE_WIDTH = 60; private static final int PADDLE_HEIGHT = 10; private static final int PADDLE_Y_OFFSET = 30; private static final int NBRICKS_PER_ROW = 10; private static final int NBRICK_ROWS = 10; private static final int BRICK_SEP = 3; private static final int BRICK_WIDTH = (WIDTH - (NBRICKS_PER_ROW - 1) * BRICK_SEP) / NBRICKS_PER_ROW; private static final int BRICK_HEIGHT = 8; private static final int BALL_RADIUS = 10; private static final int BRICK_Y_OFFSET = 70; private static final int NTURNS = 3; private static final int DELAY = 30; public void run() { setup(); GRect Paddle = new GRect(0,HEIGHT - PADDLE_HEIGHT - PADDLE_Y_OFFSET,PADDLE_WIDTH,PADDLE_HEIGHT); add(Paddle); addMouseListeners(); } private void setup() { int xStart = (WIDTH - ((NBRICKS_PER_ROW * BRICK_WIDTH) + ((NBRICKS_PER_ROW -1) * BRICK_SEP)))/2; int y = BRICK_Y_OFFSET; for (int i = 0; i&lt; NBRICK_ROWS; i++) { int x = xStart; for (int j = 0; j &lt; NBRICKS_PER_ROW; j++) { GRect block = new GRect(x, y, BRICK_WIDTH, BRICK_HEIGHT); if (i&lt;2) { block.setColor(Color.RED); block.setFilled(true); block.setFillColor(Color.red); } if (i==2||i==3) { block.setColor(Color.orange); block.setFilled(true); block.setFillColor(Color.orange); } if (i==4||i==5) { block.setColor(Color.yellow); block.setFilled(true); block.setFillColor(Color.yellow); } if (i==6||i==7) { block.setColor(Color.green); block.setFilled(true); block.setFillColor(Color.green); } if (i==8||i==9) { block.setColor(Color.cyan); block.setFilled(true); block.setFillColor(Color.cyan); } add (block); x=x+BRICK_WIDTH + BRICK_SEP; } y=y+BRICK_HEIGHT+BRICK_SEP; } } public void mouseMoved(MouseEvent PadX) { if(PadX.getX() - Paddle.getWidth()&gt;0) { Paddle.move(PadX.getX()-Paddle.getX()-Paddle.getWidth(), 0); } } private GRect Paddle; } </code></pre>
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    1. USAndrew Thompson
    1. USdwilbank
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    1. PO
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      1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
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      1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
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    1. COIs this [tag:homework]? If so, it is advantageous to tag it as such.
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      1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
      1. USAndrew Thompson
    2. COwithout stacktraces this is a waste of time and it will be closed quickly
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      1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
      1. USfeeling unwelcome
    3. COAlso, whenever you see a NullPointerException (NPE) you should carefully inspect the line that causes the exception to be thrown, for on that line is a variable that is null and that you're trying to use. What line causes your current NPE to be thrown? I also agree that you should post your entire stack-trace (the entire error message).
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      1. POmouseMoved giving null exception pointer - completely baffled (more Stanford CS106 pain)
      1. USHovercraft Full Of Eels
 

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