编写 Java 辅助方法

Question

我有 4 个 classes，火箭、三角形、正方形和圆形。

火箭是主要的 class，它允许在动画屏幕中创建火箭的表示。火箭由 3 种形状组成，三角形是机头，正方形是 body，圆形是喷气机。火箭以垂直编队定向。其他 3 个 class 定义形状的特征。

我需要编写一个辅助方法 'getBodyXPos()' 所以它 returns 一个合适的值，相对于鼻子的位置。鼻子的位置已经定义，所以我需要在代码中使用现有值，这样如果鼻子移动，body 将随之移动它的位置，即不是硬编码值。

这是我的第一个 post，很抱歉代码转储。我很确定这有一个非常简单的解决方案，但我是 Java 的新手，而且我一辈子都找不到一种方法来获得我需要的值。任何帮助将不胜感激，谢谢！

火箭Class

import ou.*;
public class Rocket
{   
   private Triangle nose;      // represents the rocket's nose cone
   private Square body;        // represents the rocket's body
   private Circle jet;         // represents the blast from the rocket's engine

   /**
    * Constructor for objects of class Rocket
    */
   public Rocket(Triangle t, Square s, Circle c)
   {
      //references to the  shape objects
      this.nose = t;
      this.body = s; 
      this.jet = c;    

      //sets the initial positions of the nose.
      //The other parts need to be set relative to these positions.
      this.nose.setXPos(50);
      this.nose.setYPos(300);

      //sets the body relative to the nose, using the helper methods
      this.body.setXPos(getBodyXPos());
      this.body.setYPos(getBodyYPos());      

      this.jet.setColour(OUColour.WHITE); 
      this.jet.setDiameter(10);           

      this.jet.setXPos(getJetXPos()); 
      this.jet.setYPos(getJetYPos()); 
   }

   private int getBodyXPos()
   {
     //SOLUTION HERE
     return 0;
   }

   private int getBodyYPos()
   {
          
     return 0;
   }
}

三角形Class

import ou.*;

public class Triangle extends OUAnimatedObject
{
/* Instance variables */

   private OUColour colour;
   private int xPos;
   private int yPos;
   private int width;
   private int height;
   
   /**
    * Constructor for objects of class Triangle with the default characteristics.
    */
   public Triangle()
   {
      this.colour = OUColour.RED;
      this.xPos = 0;
      this.yPos = 0;
      this.width = 20;
      this.height = 20;
   }

/* Instance methods */     
     
   /**
    * Sets the colour of the receiver to the value of the argument aColour.
    */
   public void setColour (OUColour aColour)
   {
      this.colour = aColour;
      this.update();
   }
   
   /**
    * Returns the colour of the receiver.
    */
   public OUColour getColour ()
   {
      return this.colour;
   }
   
   /**
    * Sets the horizontal position of the receiver to the value of the argument x.
    */
   public void setXPos(int x)
   {
      this.xPos = x;
      this.update();
   }
   
   /**
    * Returns the horizontal position of the receiver.
    */
   public int getXPos()
   {
      return this.xPos;
   }
   
   /**
    * Sets the vertical position of the receiver to the value of the argument y.
    */
   public void setYPos(int y)
   {
      this.yPos = y;
      this.update();
   }
   
   /**
    * Returns the vertical position of the receiver.
    */
   public int getYPos()
   {
      return this.yPos;
   }
   
   /**
    * Sets the width of the receiver to the value of the argument aWidth.
    */
   public void setWidth(int aWidth)
   {
      this.width = aWidth;
      this.update();
   }
   
   /**
    * Returns the width of the receiver.
    */
   public int getWidth()
   {
      return this.width;
   }
   
   /**
    * Sets the height of the receiver to the value of the argument aHeight.
    */
   public void setHeight(int aHeight)
   {
      this.height = aHeight;
      this.update();
   }
   
   /**
    * Returns the height of the receiver.
    */
   public int getHeight()
   {
      return this.height;
   }
   
   /**
    * Returns a string representation of the receiver.
    */
   public String toString()
   {
      return "An instance of class "+ this.getClass().getName() 
             + ": position (" + this.getXPos() + ", " + this.getYPos()
             + "), width " + this.getWidth() + ", height " + this.getHeight()
             + ", colour " + this.getColour();
   }
}

广场Class

import ou.*;
 
public class Square extends OUAnimatedObject
{
/* Instance variables */

   private int length;
   private OUColour colour;
   private int xPos;
   private int yPos;
   
   /**
    * Constructor for objects of class Square with the default characteristics.
    */
   public Square()
   {
      this.length = 20;
      this.colour = OUColour.BLUE;
      this.xPos = 0;
      this.yPos = 0;
   }

/* Instance methods */    
    
   /**
    * Sets the length of the receiver to the value of the argument aLength.
    */
   public void setLength(int aLength)
   {
      this.length = aLength;
      this.update();
   }
   
   /**
    * Returns the length of the receiver.
    */
   public int getLength()
   {
      return this.length;
   }
   
   /**
    * Sets the colour of the receiver to the value of the argument aColour.
    */
   public void setColour (OUColour aColour)
   {
      this.colour = aColour;
      this.update();
   }
   
   /**
    * Returns the colour of the receiver.
    */
   public OUColour getColour ()
   {
      return this.colour;
   }
   
   /**
    * Sets the horizontal position of the receiver to the value of the argument x.
    */
   public void setXPos(int x)
   {
      this.xPos = x;
      this.update();
   }
   
   /**
    * Returns the horizontal position of the receiver.
    */
   public int getXPos()
   {
      return this.xPos;
   }
   
   /**
    * Sets the vertical position of the receiver to the value of the argument y.
    */
   public void setYPos(int y)
   {
      this.yPos = y;
      this.update();
   }
   
   /**
    * Returns the vertical position of the receiver.
    */
   public int getYPos()
   {
      return this.yPos;
   }
   
   /**
    * Returns a string representation of the receiver.
    */
   public String toString()
   {
      return "An instance of class "+ this.getClass().getName() 
             + ": position (" + this.getXPos() + ", " + this.getYPos() 
             + "), length " + this.getLength() + ", colour " + this.getColour();
   }
   
}

Answer 1

希望 Body 开始位置总是与 Nose 开始一些东西对齐

  /\
 /  \ 
 ----
 |__|

在这种情况下，Nose 的 X 将是 Body 的 X 和 bodyY = noseY + noseHeight

private int getBodyXPos(){
    return nose.getXpos();
}

private int getBodyYPos(){
    return nose.getYpos() + nose.getheight();
}

编写 Java 辅助方法

Writing Java helper method

java

helper

getter