crocodile.java

ssd1 exercise7 以前做的 希望有帮助

import java.util.Vector;
/*
 * Created on Jul 6, 2003
 *
 */

/**
 * Crocodile - to simulate artificial life. Eats small fish.
 * 
 * @author iCarnegie av
 *
 */
public class Crocodile extends LivingBeing {
	
	/**
	 * The crocodile is born "alive". 
	 * Then it dies, becoming a corpse. 
	 */
	private static final String ALIVE = "alive";

	/**
	 * The crocodile is born "alive". 
	 * Then it dies, becoming a "dead" corpse. 
	 */
	private static final String DEAD = "dead";


	/**
	 * Energy expended to wade during a block of time.
	 */
	private static final int ENERGY_TO_WADE = 10;
	
	/**
	 * Energy expended to eat once.
	 */
	private static final int ENERGY_TO_EAT = 10;
		
	/**
	 * Lowest possible energy needed for a baby to survive. 
	 */
	private static final int BABY_MIN_ENERGY = 1000;
	
	/**
	 * Maximum energy that a baby can store. 
	 */
	private static final int BABY_MAX_ENERGY = 2000;

	/**
	 * For each block of time, the min energy grows by a certain amount
	 */
	private static final int MIN_ENERGY_GROWTH_INCREMENT = 5;
	
	/**
	 * For each block of time, the max energy grows by a certain amount
	 */
	private static final int MAX_ENERGY_GROWTH_INCREMENT = 10; 

	// Concept example: final. since it is a constant 
	// Concept example: static. since only one value is needed 
	// 						irrespective of number of object instances 
	/**
	 * String constant - used to indicate the direction crocodile is facing.
	 */
	private static final String RIGHT = "right";

	/**
	 * String constant - used to indicate the direction crocodile is facing.
	 */
	private static final String LEFT = "left";

	/**
	 * String constant - used to indicate the direction crocodile is facing.
	 */
	private static final String UP = "up";

	/**
	 * String constant - used to indicate the direction crocodile is facing.
	 */
	private static final String DOWN = "down";

	/**
	 * Name of species
	 */
	private static final String SPECIES = "Crocodile";

	/**
	 * Row-wise location of the crocodile
	 */
	private int row;

	/**
	 * Column-wise location of the crocodile
	 */
	private int column;

	/**
	 * Is the crocodile dead or alive?
	 */
	private String deadOrAlive;
	
	/**
	 * Amount of energy the crocodile has.
	 */
	private int energy;

	/**
	 * Age expressed as blocks of time lived
	 */
	private int age = 0;

	/**
	 * Name of this crocodile.
	 */
	private final String name;

	/**
	 * The simulation to which this crocodile belongs.
	 * This is needed so the crocodile can send a message 
	 * to simulation and ask
	 * for prey (or predator) in the neighboring locations. 
	 * Prey is food. Food is good!
	 */
	private Simulation simulation;

	/**
	 * Minimum energy level needed to survive.
	 * The minimum could increase as the individual grows.
	 */
	private int minEnergy;
	
	/**
	 * Maximum energy level that the crocodile could carry.
	 * The maximum could change as the individual grows.
	 */
	private int maxEnergy;
	
	/**
	 * Which direction am I facing.
	 */
	private String direction; 

	/**
	 * Number of Crocodiles created so far
	 */
	private static int nCrocodilesCreated = 0;

	/**
	 * Construct and initialize a Crocodile.
	 * 
	 * @param initialRow - the row at which the crocodile is located
	 * @param initialColumn - the column at which the crocodile is located
	 * @param initialSimulation - the simulation that the crocodile belongs to
	 */
	public Crocodile(
		int initialRow,
		int initialColumn,
		Simulation initialSimulation) {

			simulation = initialSimulation;

			deadOrAlive = ALIVE; 

			// Set the Row within bounds
			if (initialRow > initialSimulation.getLastRow()) {
				row = initialSimulation.getLastRow();
			} else if (initialRow < initialSimulation.getFirstRow()) {
				row = initialSimulation.getFirstRow();
			} else {
				row = initialRow;
			}

			// Set the Column within bounds
			if (initialColumn > initialSimulation.getLastColumn()) {
				column = initialSimulation.getLastColumn();
			} else if (initialColumn < initialSimulation.getFirstColumn()) {
				column = initialSimulation.getFirstColumn();
			} else {
				column = initialColumn;
			}

			// Set the minEnergy and maxEnergy
			minEnergy = BABY_MIN_ENERGY;
			maxEnergy = BABY_MAX_ENERGY;

			energy =
				simulation.getRand().nextInt(maxEnergy - minEnergy) + minEnergy;

			age = 0;
			name = SPECIES + nCrocodilesCreated;

			direction = RIGHT; // Start by facing east.

			++nCrocodilesCreated;
	}

	/**
	 * Get the row at which the crocodile is located 
	 * 
	 * @return - the row of the crocodile's location. 
	 */		
	public int getRow() {
		return row;
	}

	/**
	 * Get the column at which the crocodile is located
	 * 
	 * @return - the column of the crocodile's location. 
	 */		
	public int getColumn() {
		return column;
	}

	/**
	 * Get the crocodile's age
	 * 
	 * @return the age of the crocodile expressed in blocks of time
	 */
	public int getAge() {
		return age;
	}

	/**
	 * Color of the crocodile expressed in hex notation.
	 * For example, the "green-est" color is "#00FF00",
	 * "blue-est" is "#0000FF", the "red-est" is "#FF0000".
	 * 
	 * @return the rgb color in hex notation. preceded by a pound character '#'
	 */
	public String getColor() {
		return "#FFFFFF"; // default is white.
	}

	/**
	 * Get the name of this crocodile
	 * 
	 * @return the name of the crocodile.
	 */
	public String getName() {
		return name;
	}

	/**
	 * Get the minimum energy needed to live.
	 * 
	 * @return the minimum energy needed for the crocodile to live.
	 */
	private int getMinEnergy() {
		return minEnergy;
	}
	
	/**
	 * get the maximum energy that the crocodile can carry.
	 * 
	 * @return the maximum energy the crocodile can carry.
	 */
	private int getMaxEnergy() {
		return maxEnergy;
	}
	
	/**
	 * Get the energy currently carried by the crocodile.
	 * 
	 * @return current energy level of the organism
	 */
	public int getEnergy() {
		return energy;
	}

	/**
	 * Sets energy level.
	 * If new energy level is less than minimum energy level, the organism dies.
	 * New energy level is capped at maximum energy level.
	 */
	private void setEnergy(int newEnergy) {
		
		if (newEnergy < getMinEnergy()) {
			energy = newEnergy;
			die();
		} else if (newEnergy > getMaxEnergy()) {
			energy = getMaxEnergy();
		} else {
			energy = newEnergy;
		}
	}

	/**
	 * Die: Change the deadOrAlive to DEAD.
	 */
	private void die() {
		deadOrAlive = DEAD;
	}

	/**
	 * Is the crocodile dead?
	 * 
	 * @return <code>true</code> if dead. <code>false</code>, otherwise.
	 */
	public boolean isDead() {
		return (deadOrAlive == DEAD);
	}

	/**
	 * Get the direction faced by the crocodile.
	 * 
	 * @return the facing direction.
	 */
	private String getDirection() {
		return direction;
	}

	/** 
	 * Is the crocodile hungry?
	 * 
	 * @return True, if hungry. False, otherwise.
	 */
	private boolean isHungry() {
		
		// Hungry, if current energy level is less than twice the 
		// amount needed for survival.
		return (getEnergy() < (2 * getMinEnergy()));
	}

	/**
	 * Move the crocodile to a new row, if new row is within lake bounds.
	 * 
	 * @param newRow - the row to move to.
	 * @return the row moved to. Lake boundary limits movement. -1, if dead.
	 */
	private int moveToRow(int newRow) {
		
		if (isDead()) {
			return -1;
		}

		// Keep the new value within lake boundary.
		if (newRow > simulation.getLastRow()) {
			newRow = simulation.getLastRow();
		} else if (newRow < simulation.getFirstRow()) {
			newRow = simulation.getFirstRow();
		}

		// I might face a new direction.
		if (newRow < row) {
			direction = UP;
		} else if (newRow > row) {
			direction = DOWN;
		}
		row = newRow;

		return row;
	}

	/**
	 * Move the crocodile to a new column, if new column is within lake bounds.
	 * 
	 * @param newColumn - the column to move to.
	 * @return the column moved to. Lake boundary limits movement.
	 */
	private int moveToColumn(int newColumn) {

		if (isDead()) {
			return -1;
		}

		// System.out.println("column = " + column + ", newCOlumn = " + newColumn);
		// System.out.flush();
		// Keep the new value within lake boundary.
		if (newColumn > simulation.getLastColumn()) {
			newColumn = simulation.getLastColumn();
		} else if (newColumn < simulation.getFirstColumn()) {
			newColumn = simulation.getFirstColumn();
		}

		// I might face a new direction.
		if (newColumn < column) {
			direction = LEFT;
		} else if (newColumn > column) {
			direction = RIGHT;
		}

		column = newColumn;

		return column;
	}

	/**
	 * Get the species
	 * 
	 * @return a string indicating the species
	 */
	public String getSpecies() {
		return SPECIES;
	}

	/**
	 * The display mechanism to use to display a crocodile.
	 * 
	 * @return a constant defined in {@link Simulation#IMAGE Simulation} class
	 */
	public String getDisplayMechanism() {
		return Simulation.IMAGE;
	}
	
	/**
	 * Get the filename that contains an image of the Crocodile
	 * 
	 * @return filename of Crocodile image
	 */
	public String getImage() {

		if (getDirection() == RIGHT) {
			return "/Crocodile-right.gif";
		}
		if (getDirection() == LEFT) {
			return "/Crocodile-left.gif";
		}
		if (getDirection() == UP) {
			return "/Crocodile-up.gif";
		}
		if (getDirection() == DOWN) {
			return "/Crocodile-down.gif";
		}

		return "Crocodile-right.gif";
	}

	/** 
	 * Wade to a new location if possible.
	 * Consumes some energy.
	 */
	private void wadeIfPossible() {

		int firstRow; // lake boundary
		int firstColumn; // lake boundary
		int lastRow; // lake boundary
		int lastColumn; // lake boundary
		int newRow; // new location for croc
		int newColumn; // new location for croc
		
		// Consume energy to swim.
		setEnergy(
			getEnergy() - ENERGY_TO_WADE);
		if (isDead()) {
			return;
		}

		// get the lake boundary.
		firstRow = simulation.getFirstRow();
		firstColumn = simulation.getFirstColumn();
		lastRow = simulation.getLastRow();
		lastColumn = simulation.getLastColumn();

		// Wade to a random location in the lake.
		newRow = simulation.getRand().nextInt(lastRow - firstRow + 1);
		newColumn = simulation.getRand().nextInt(lastColumn - firstColumn + 1);
		newRow = newRow + firstRow;
		newColumn = newColumn + firstColumn;

		// Move to the new location.
		moveToRow(newRow);
		moveToColumn(newColumn);

		return;
	}

	/**
	 * Eat if food is available in the current location.
	 */
	private void eatIfPossible() {

		Vector foodMaybe;
		int neighborIndex;

		if (isDead()) {
			return;
		}

		foodMaybe = simulation.getNeighbors(getRow(), getColumn(), 0);
		for (neighborIndex = 0;
			neighborIndex < foodMaybe.size();
			++neighborIndex) {

			if (foodMaybe.get(neighborIndex) instanceof Catfish) {

				Catfish fish = (Catfish) foodMaybe.get(neighborIndex);
				int energyGained = fish.getEnergy();
				fish.die();

				// Gain energy. 
				// And spend ENERGY_TO_EAT, irrespective of amount gained.
				setEnergy(getEnergy() + energyGained - ENERGY_TO_EAT);
			}
		}
	}

	/**
	 * Live for a block of time.
	 */
	public void liveALittle() {

		if (isDead()) {
			return;
		}
		age = age + 1;
		wadeIfPossible();
		eatIfPossible();
		
		// As I am growing bigger, I need to increase my minEnergy 
		// and maxEnergy.
		minEnergy = getMinEnergy() + MIN_ENERGY_GROWTH_INCREMENT;
		maxEnergy = getMaxEnergy() + MAX_ENERGY_GROWTH_INCREMENT; 
	}
}