java - 我如何在这段代码中使随机对象移动？

Question

事情是这样的，基本上我必须有一个代码，其中有一个桶可以接住掉落的水果，每次接住它时，你都会得到一个新水果掉落的分数。

所以我知道如何让桶移动，以及如何让水果到达底部后再次移动。但是，我不知道如何让它真正落下。到目前为止，我有一个开关，但不知道该怎么用它。我在随机的地方突然出现了水果，这是一个开始。无论如何，这是我的代码。感谢所有帮助。再说一遍，一旦其中一个到达底部，我需要随机掉落一个水果。

import java.awt.Color;
import java.awt.event.KeyEvent;

import acm.graphics.GOval;
import acm.graphics.GPolygon;
import acm.graphics.GRect;
import acm.program.GraphicsProgram;
import acm.util.RandomGenerator;

import java.awt.event.*;

public class FruitCatcher extends GraphicsProgram {
	private static final int APPLET_WIDTH = 500;
	private static final int APPLET_HEIGHT = 500;
	private static final int BUCKET_X = 250;
	private static final int BUCKET_Y = 500;
	private static final int BUCKET_SPEED = 10;
	private static final int BUCKET_SPEED2 = -10;

	private GPolygon Bucket;

	public void init() {
		setSize(APPLET_WIDTH, APPLET_HEIGHT);
		addKeyListeners();
	}

	public void run() {
		RandomGenerator random = new RandomGenerator();

		makeBucket();
		for (int i = 1; i <= 3; i++) {

			int randomX = random.nextInt(0, 300 - 20);

			addFruit(i, randomX, 0);
		}
		while (true)
			;

	}

	public void makeBucket() {
		Bucket = new GPolygon(BUCKET_X, BUCKET_Y);
		Bucket.addVertex(-60, 0);
		Bucket.addVertex(-70, -85);
		Bucket.addVertex(10, -85);
		Bucket.addVertex(0, 0);

		add(Bucket);
		Bucket.setFilled(true);
		Bucket.setFillColor(Color.GRAY);
	}

	public void addFruit(int a, int x, int y) {

		switch (a) {
		case 1:
			GRect Banana = new GRect(x, y, 10, 60);
			Banana.setColor(Color.YELLOW);
			Banana.setFilled(true);
			add(Banana);
			break;
		case 2:
			GOval lime = new GOval(x, y, 20, 20);
			lime.setColor(Color.GREEN);
			lime.setFilled(true);
			add(lime);
			break;
		case 3:
			GOval Orange = new GOval(x, y, 30, 30);
			Orange.setColor(Color.ORANGE);
			Orange.setFilled(true);
			add(Orange);
		}

	}

	public void keyPressed(KeyEvent event) {
		int keyCode = event.getKeyCode();
		switch (keyCode) {
		case KeyEvent.VK_LEFT:
			if (Bucket.getX() > 0) {
				Bucket.move(-BUCKET_SPEED, 0);
			}
			break;
		case KeyEvent.VK_RIGHT:
			if (Bucket.getX() < APPLET_WIDTH) {
				Bucket.move(BUCKET_SPEED, 0);
			}
			break;
		}
	}
}

在我的代码中，您可以看到一段时间(正确)我只是假设那是我要编写它的地方。然而，我有点不知所措。

Answer 1

• 您需要保留所有水果的引用列表，以便以后可以操作它们
• 游戏循环的每次迭代，将每个水果向下移动

• 你可能想实现一些定时机制，以便水果速度不依赖于 CPU 速度。

  package jsyn;
  
  import java.awt.Color;
  import java.awt.Component;
  import java.awt.event.KeyEvent;
  import java.util.ArrayList;
  import java.util.List;
  
  import acm.graphics.GOval;
  import acm.graphics.GPolygon;
  import acm.graphics.GRect;
  import acm.program.GraphicsProgram;
  import acm.util.RandomGenerator;
  
  import java.awt.event.*;
  
  public class FruitCatcher extends GraphicsProgram {
  private static final int APPLET_WIDTH = 500;
  private static final int APPLET_HEIGHT = 500;
  private static final int BUCKET_X = 250;
  private static final int BUCKET_Y = 500;
  private static final int BUCKET_SPEED = 10;
  private static final int BUCKET_SPEED2 = -10;
  
  //Speed of fruit falling
  private static final int FRUIT_PX_PER_MS = 10;
  
  private GPolygon Bucket;
  
  public void init() {
      setSize(APPLET_WIDTH, APPLET_HEIGHT);
      addKeyListeners();
      fruits = new ArrayList<Component>();
  }
  
  // Keep list of fruits
  List<GObject> fruits;
  
  public void run() {
      RandomGenerator random = new RandomGenerator();
  
      makeBucket();
      for (int i = 1; i <= 3; i++) {
  
          int randomX = random.nextInt(0, 300 - 20);
  
          addFruit(i, randomX, 0);
      }
  
      long last = System.currentTimeMillis();
      while (true) {
          long current = System.currentTimeMillis();
          update(current - last);
          last = current;
      }
  }
  
  void update(long delta) {
      for (GObject fruit : fruits) {
          //this code may not work, replace with code that moves fruit down
          fruit.setLocation(fruit.getX(), fruit.getY() + delta * FRUIT_PX_PER_MS);
      }
  }
  
  public void makeBucket() {
      Bucket = new GPolygon(BUCKET_X, BUCKET_Y);
      Bucket.addVertex(-60, 0);
      Bucket.addVertex(-70, -85);
      Bucket.addVertex(10, -85);
      Bucket.addVertex(0, 0);
  
      add(Bucket);
      Bucket.setFilled(true);
      Bucket.setFillColor(Color.GRAY);
  }
  
  public void addFruit(int a, int x, int y) {
  
      switch (a) {
      case 1:
          GRect Banana = new GRect(x, y, 10, 60);
          Banana.setColor(Color.YELLOW);
          Banana.setFilled(true);
          add(Banana);
          fruits.add(Banana);
          break;
      case 2:
          GOval lime = new GOval(x, y, 20, 20);
          lime.setColor(Color.GREEN);
          lime.setFilled(true);
          add(lime);
          fruits.add(lime);
          break;
      case 3:
          GOval Orange = new GOval(x, y, 30, 30);
          Orange.setColor(Color.ORANGE);
          Orange.setFilled(true);
          add(Orange);
          fruits.add(Orange);
      }
  
  }
  
  public void keyPressed(KeyEvent event) {
      int keyCode = event.getKeyCode();
      switch (keyCode) {
      case KeyEvent.VK_LEFT:
          if (Bucket.getX() > 0) {
              Bucket.move(-BUCKET_SPEED, 0);
          }
          break;
      case KeyEvent.VK_RIGHT:
          if (Bucket.getX() < APPLET_WIDTH) {
              Bucket.move(BUCKET_SPEED, 0);
          }
          break;
      }
  }
  }