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POCalling methods from other classes java
 

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    <p>I have just started programming some things with Greenfoot, learning java along the way. I have become familiar on how to call certain methods between classes, and also differences between static and non-static.</p> <p>I'm makeing a game where you play the crab and move around to collect worms. There is a lobster that randomly roams around and if comes in contact with the crab, the crab dissapears. Every time you eat a worm, the score goes up by 10.</p> <p>It contains 5 classes named Crab, Lobster, Worm, Counter, and CrabWorld. For your sake, I'll just post the well documented code for you to read. But the important part that I am having trouble with is calling a method from the lobster to the Crab instance created by the CrabWorld. This method would change the lives of the crab. </p> <p>I have tried calling ((CrabWorld) getWorld), but I don't need to access the CrabWorld. I need to access the Crab instance (created in the CrabWorld, if that matters) from from the Lobster Class.</p> <p>Crabworld:</p> <pre><code>import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo) /** * Creates the crab Enviornment with a counter, crab and lobster. Also has methods to * place random worms in the world over time. Also has a method to add the score * To the Counter score * @author Troy Bick * @version 12/20/13 */ public class CrabWorld extends World { private Actor playerCrab = new Crab(); private Counter score = new Counter("Score: "); /** * Constructor for objects of class CrabWorld. * */ public CrabWorld() { super(560, 560, 1); prepare(); } /** * Prepare the world for the start of the program. That is: create the initial * objects and add them to the world. */ private void prepare() { addObject(score, 100, 540); addObject(playerCrab, 280, 280); addObject(new Lobster(), 100, 100); } /** * Randomly places worms at random periods */ public void act() { if(Greenfoot.getRandomNumber(100)&lt;0.5){ addObject(new Worm(), Greenfoot.getRandomNumber(540)+10, Greenfoot.getRandomNumber(540)+10); } } public void eatenWorm() { score.add(10); } public void eatsCrab() { playerCrab.isEaten(); } </code></pre> <p>Crab:</p> <pre><code>import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo) public class Crab extends Actor { private int wormsEaten = 0; private int lives = 3; /** * Act - do whatever the Crab wants to do. This method is called whenever * the 'Act' or 'Run' button gets pressed in the environment. Run calls Act every * frame. */ public void act() { moveAndTurn(); eat(); } /** * Determines the key pressed and moves/turns the crab. */ public void moveAndTurn() { move(3); if(Greenfoot.isKeyDown("a")){ turn(3); } if(Greenfoot.isKeyDown("d")){ turn(-3); } } /** * Detects if the worm is close to the crab, and if so, eats it. */ public void eat() { Actor worm; worm = getOneObjectAtOffset(0,0,Worm.class); World world = getWorld(); if(worm != null) { world.removeObject(worm); Greenfoot.playSound("eating.wav"); wormsEaten++; ((CrabWorld) getWorld()).eatenWorm(); } } /** * Returns the number of worms eaten. */ public int getWormsEaten() { return wormsEaten; } /** * Returns the number the lives the crab has left. */ public int getLivesCount() { return lives; } /** * Subtracts a life from lives. */ public void eaten() { lives--; } } </code></pre> <p>Lobster:</p> <pre><code>import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo) /** * Write a description of class Lobster here. * * @author (your name) * @version (a version number or a date) */ public class Lobster extends Actor { /** * Act - do whatever the Lobster wants to do. This method is called whenever * the 'Act' or 'Run' button gets pressed in the environment. */ public void act() { moveAround(); eat(); } public void eat() { Actor crab; crab = getOneObjectAtOffset(0,0,Crab.class); if(crab != null) { World world = getWorld(); world.removeObject(crab); ((CrabWorld) getWorld()).eatsCrab(); } } public void moveAround() { move(3); //Random Movements if(Greenfoot.getRandomNumber(100) &lt; 10) { turn(Greenfoot.getRandomNumber(40) - 20); } //World Edge Detection if(getX() &lt;= 10 || getX() &gt;= getWorld().getWidth()-10) { turn(10); } if(getY() &lt;= 10 || getY() &gt;= getWorld().getHeight()-10) { turn(10); } } } </code></pre> <p>So when the lobster that has be added to the world eats the crab, I want that crab to lose a life, but when I try to compile, I get an error on the CrabWorld class that it could not find the method mentioned. Why is that?</p> <p>Just very confused... If anyone could help me that would be great. If I'm missing anything, I fix it. </p> <p>Thanks in advanced, Troy</p>
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    1. COWhat's the exact compilation error?
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    2. COLooks like you're missing a `}` at the end of the Crabworld file.
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      1. USirrelephant
    3. COI think this is a **typo** question. Your `Crab` has a method `eaten()`, but you try to call `isEaten()` from the `CrabWorld`. However, you should really post the actual error message if you want help.
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      1. USDaoWen
 

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