从我的arrayList（Java）获取特定的对象

Question

嗨，我的问题是，在我的代码中，我打电话的方法，计算2点之间的差异，然后如果该距离少于7它将调用另一个类的方法，应该改变目标的颜色为红色......我的问题是，在我的数组列表中，我有3个或5个或取决于用户输入目标...所以我如何指定我的数组列表中的对象将要改变颜色> ???这是我的代码

package project1; 

import java.util.*; 
import javax.swing.*; 

/** 
* 
* @author Elvis De Abreu 
*/ 
public class TargetGallery 
{ 
    /**ArrayList of Targets initialize as a private*/ 
    private ArrayList<Target> mytargets = new ArrayList<>(); 
    /**Static object for the Target class*/ 
    static Target tg = new Target(); 
    /**Static object for the RifleSite class*/ 
    static RifleSite rs = new RifleSite(); 
    /**Static object for the TargetGallery class*/ 
    static TargetGallery tgy = new TargetGallery(); 
    /**the number of targets input by the user as private*/ 
    private int number = 0; 
    /**array that store the distance between 2 point for each target*/ 
    private double[] total; 

    /** 
    * Method that build the background of the canvas 
    * with a picture as a environment 
    */ 
    private void buildWorld() 
    { 
     StdDraw.setXscale(0, 250); 
     StdDraw.setYscale(0, 250); 
     StdDraw.picture(75, 130, "bath.jpeg", 450, 285); 
    } 

    /** 
    * Method that draw a weapon in the middle of the 
    * canvas as a shooter weapon 
    */ 
    private void drawShooter() 
    { 
     StdDraw.setXscale(0, 250); 
     StdDraw.setYscale(0, 250); 
     StdDraw.picture(125, 0, "weapon.png", 80, 45); 
    } 

    /** 
    * randomly generates X locations for the targets 
    * add them into the array list 
    */ 
    private void createTargets() 
    { 
     double x = 125; 
     double y = 175; 
     double radius = 7; 

     String input = JOptionPane.showInputDialog("Type a number" + 
       "between 2 and 5"); 

     number = Integer.parseInt(input); 

     for(int i = 0; i < number; i++) 
     { 
      Target targ = new Target(x, y, radius); 
      mytargets.add(targ); 
      Random rand = new Random(); 
      x = rand.nextInt(400) + 10; 

      for (Target e: mytargets) 
      { 
       if ((e.getX() <= (x+10)) || (e.getX() >= (x-10))) 
       { 
        mytargets.clear(); 
        i--; 
        continue; 
       } 
      } 
     } 
    } 

    /** 
    * Method that run different methods which start the program 
    */ 
    public void run() 
    { 

     tgy.buildWorld();   //call the buildWorld method 
     tgy.drawShooter();   //call the drawShooter method 
     tgy.createTargets();  //call the createTarget method 
     tgy.simulate();    //call the simulate method 
    } 

    /** 
    * calculates the distance between the RifleSite and the Targets 
    */ 
    public void calcDistance() 
    { 
     //variable declaration/initialization 
     double distance; 
     double distance1; 
     int i = 0; 

     total = new double[number]; 

     //for each loop to calculate x and y location of RifleSite and Targets 
     for (Target e: mytargets) 
     { 
      distance = Math.pow(e.getX()-rs.getX(), 2.0); 
      distance1 = Math.pow(e.getY()-rs.getY(), 2.0); 
      total[i++] = Math.sqrt(distance + distance1); 
     } 
    } 

    /** 
    * Method that simulates the game 
    */ 
    public void simulate() 
    { 
     //Variable declaration/initialization 
     boolean alive = true; 

     for(Target e: mytargets) 
     { 
      e.drawAlive(); 
     } 

     rs.drawRifleSite(); 

     //loop that will run while there is still targets alive or user press q 
     while(alive == true) 
     { 
      //if user press a key this 
      if (StdDraw.hasNextKeyTyped()) 
      { 
       char ch = StdDraw.nextKeyTyped(); //store the key pressed 
       //if person press Q will quit the program 
       if (ch == 'q') 
       { 
        int done = JOptionPane.showConfirmDialog(null, 
          "The Program will close now bye :)"); 
        System.exit(0); 
       } 

       else if (ch == 'f') 
       { 
        tgy.calcDistance();  //calculates the distance 

        //if statement to check if the distance if less than radius 
        for(int i = 0; i < number; i++) 
        { 
         if (total[i] <= 7) 
         { 
          //THIS IS WHERE MY METHOD SHOULD GO 
          //SHOULD BE SOMETHING LIKE E.drawDead 
         } 

        } 
       } 


      } 
     } 
    } 










    /** 
    * Method for the main of the Program 
    * @param args the command line arguments 
    */ 
    public static void main(String[] args) 
    { 

    } 
} 

Answer 1

像这样：mytargets.get(INDEX GO HERE) 我希望帮助

（索引从0开始）

例如：

Target t=mytargets.get(0); 
if ((t.getX() > 10) && (t.getY() > 10)) 
{ 
    //blablabla 
}