不能使用另一個類的方法？

Question

我知道有一些有類似標題的其他線程，但我已經做了在那些線程提出的一切。

我試圖做一個恐龍的賽車遊戲稱爲化石燃料，現在我創造了障礙從需要避免頂灑落在一般的遊戲。

我知道Python和最近纔開始學習Java，所以這個問題可能聽起來很愚蠢，但在這裏不用。

import javax.swing.JFrame; 
import javax.swing.ImageIcon; 
import javax.swing.JLabel; 

import java.lang.System; 
import java.util.ArrayList; 
import java.lang.Math; 
public class MainLoop 
{ 
    public static void main(String [] args) 
    { 
     boolean mloop = true; 
     int obsMoveIncrease = 1; 
     ArrayList obsList = new ArrayList(); 
     final String[] validObsTypes = {"tree", "rock", "bush"}; 
     long moveFrequency = 750; 
     long beginningTime = System.currentTimeMillis(); 
     long obsInterval = 3000; //how often a new object is created in milliseconds 
     long timeOfLastMove = System.currentTimeMillis(); 
     JFrame frame = new JFrame(); 
     ImageIcon background = new ImageIcon("background.jpg"); //background is 700 by 1500 px 
     JLabel bgLabel = new JLabel(background); 
     frame.add(bgLabel); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.pack(); 
     frame.setVisible(true); 
     while (mloop) 
     { 
      int freshObsTypeNum = (int) Math.random() * 3; 
      String freshObsType = validObsTypes[freshObsTypeNum]; //chooses a pseudo-random valid obstacle type 
      if (System.currentTimeMillis() >= beginningTime + obsInterval) 
      { //checks if sufficient time has passed since last obstacle was created 
       Obstacle obs = new Obstacle(freshObsType, 0); 
       obsList.add(0, obs); 
       beginningTime = System.currentTimeMillis(); //resets "clock" 
      } 


      if (System.currentTimeMillis() >= timeOfLastMove + moveFrequency) //checks if it is time to move obstacles 
      { 
       timeOfLastMove = System.currentTimeMillis(); 
       for (int i = 0; i < obsList.size(); i++) 
       { 
        obsList.get(i).moveObs(obsMoveIncrease); //moves obstacles ERROR OCCURS ON moveObs 
        if (obsList.get(i).getObsY() > 1500) 
        { 
         obsList.remove(i); 
        } 

       } 
      } 
     } 
    } 
} 

這裏是我的障礙類：

import java.util.Arrays; 
import javax.swing.ImageIcon; 
import javax.swing.JLabel; 
public class Obstacle 
{ 
    private String obstacleType; 
    private int obstacleXPos; 
    public final int[] obsXlist = {0, 175, 350, 525}; //list of starting positions (4 slots along the x axis) 
    int obstacleYPos = 0; 
    public Obstacle(String type, int startPos) 
    { 
     obstacleType = type; 
     obstacleXPos = obsXlist[startPos]; 
    } 

    public int getObsX() 
    {return obstacleXPos;} 

    public int getObsY() 
    {return obstacleYPos;} 

    public void moveObs(int increase) 
    {obstacleYPos += increase;} 

    ImageIcon obstacleImg; 
    public JLabel getObsImg() //gets image (on a label) for keyword given to constructor 
    { 
     if (obstacleType.equals("tree")) 
      obstacleImg = new ImageIcon("treeObs.jpg"); 
     else if (obstacleType.equals("rock")) 
      obstacleImg = new ImageIcon("rockObs.jpg"); 
     else if (obstacleType.equals("bush")) 
      obstacleImg = new ImageIcon("bushObs.jpg"); 
     else 
      System.out.println(obstacleType + " is not a valid obstacle type"); 

     JLabel obsLabel = new JLabel(obstacleImg); 
     return obsLabel; 
    } 
} 

它告訴我，當我打電話從主方法中moveObs（INT）符號無法找到。我不知道爲什麼我會無法訪問的故障等級

Answer 1

obsList我的公開方法沒有一個類型。 您正嘗試在'Object'上調用moveObs（），而不是在'Obstacle'上。

要改變，你需要做obsList類型化的列表如下：

ArrayList<Obstacle> obsList = new ArrayList<>();