Java - 使用抽象類的構造函數

Question

我的任務是爲抽象類MashUpPlayer創建一個子類。 MashUpPlayer有一個構造函數。子類的構造函數必須沒有參數。客戶端代碼將無法進行其他編譯。我不確定如何在不使用給定參數實現構造函數的情況下編譯代碼。

我的代碼：

public class Wizard extends MashUpPlayer { 

    //this shouldn't have any params ?? 
    Wizard (String s, Color c){ 
     super(s,c); 
    } 

    /** 
    * method to set the color of Wizard MashUpPlayer to Gray 
    * @param c is the color 
    */ 
    public void setColor(Color c){ 
     c = Color.GRAY; 
    } 

    /** 
    *method to change the String state to "^\u221e^" 
    *@param s is the string display 
    **/ 
    public void setDisplay (String s){ 
     s= "^\u221e^"; 
    } 

    /**overrides getColor method from MashUpPlayer 
    * @return Color.GRAY 
    */ 
    public Color getColor(){ 
     return Color.GRAY; 
    } 

    /**overrides toString method from MashUpPlayer 
    * @return "^\u221e^" 
    */  
    public String toString(){ 
     return "^\u221e^"; 
    } 

    /** 
    * this method is the actions of the Wizard 
    * It will fight an Other in front of it 
    * @return Action.FIGHT 
    * It will turn right if the neighbor in front is a Wizard or a Wall 
    * @return Action.RIGHT 
    * It will travel around it's domain otherwise 
    * @return move 5 spaces, turn right, repeat 
    */ 
    public Action getMove(MashUpPlayerInfo info){ 

     //checks neighbor and fights if other  
     if(info.getFront() ==Neighbor.OTHER){ 
      return Action.FIGHT; 
     } 

     //turns right at wall or neighbor 
     if((info.getFront()==Neighbor.WALL)||(info.getFront()==Neighbor.SAME)){ 
      return Action.RIGHT; 
     } 

     //moves 5 spaces 
     if (info.getFront()==Neighbor.EMPTY){ 
      for (int i=1;i<=5;i++){ 
       return Action.MOVE; 
      } 
     } 
     //turns right 
     return Action.RIGHT; 
    } 
} 

這是抽象方法：

import java.awt.*; 
    /** 
    * This is the superclass of all of the MashUpPlayer classes. 
    * String representation. Some methods must be overriden. 

    * The class provides several kinds of constants:<p> 
    * type Neighbor : WALL, EMPTY, SAME, OTHER<br> 
    * type Action : HOP, LEFT, RIGHT, FIGHT<br> 
    * type Direction : NORTH, SOUTH, EAST, WEST<br><br> </p> 
    * 
    * Based on work by Stuart Reges and Marty Stepp          
    */ 

    public abstract class MashUpPlayer { 

    private String myDisplay; 
    private Color myColor; 

    /** 
    * Initializes this MashUpPlayer's state 
    * @param s this MashUpPlayer's initial String representation 
    * @param c this MashUpPlayer's starting color 
    */ 
    public MashUpPlayer(String s, Color c){ 
     myDisplay = s; 
     myColor = c; 
    } 

    /** 
    * This method answers this MashUpPlayer's color 
    * @return the current color 
    */ 
    public Color getColor(){ 
     return myColor; 
    } 

    /** 
    * This method answers this MashUpPlayer's String representation 
    * @return the current string 
    */ 
    public String toString(){ 
     return myDisplay; 
    } 

    /** 
    * This method allows subclasses only to change this MashUpPlayer's color 
    * @param c the new color 
    */ 
    protected void setColor(Color c){ 
     myColor = c; 
    } 

    /** 
    * This method allows subclasses only to change this MashUpPlayer's String display 
    * @param s the new display 
    */ 
    protected void setDisplay(String s){ 
     myDisplay = s; 
    } 

    /** 
    * This method answers this MashUpPlayer's Action 
    * MUST BE OVERRIDDEN IN SUBCLASSES 
    * 
    * @param info information about this MashUpPlayer in the simulation 
    * @return the current Action 
    */ 
    public abstract Action getMove(MashUpPlayerInfo info); 

    /** 
    * <div> 
    * WALL: against the wall of the simulation world<br> 
    * EMPTY: the neighboring spot is empty<br> 
    * SAME: an MashUpPlayer of the same species<br> 
    * OTHER: an MashUpPlayer of another species<br></div> 
    */ 
    public static enum Neighbor { 
     WALL, EMPTY, SAME, OTHER 
    }; 

    /** 
    * <div> 
    * MOVE: move one space in the current direction<br> 
    * LEFT: turn left by rotating 90 degrees counter-clockwise<br> 
    * RIGHT: turn right by rotating 90 degrees clockwise<br> 
    * FIGHT: fight the MashUpPlayer in front of you</div> 
    */ 
    public static enum Action { 
     MOVE, LEFT, RIGHT, FIGHT 
    }; 

    /** 
    * <div> 
    * NORTH<br> 
    * SOUTH<br> 
    * EAST<br>} 
    * WEST</div> 
    */ 
    public static enum Direction { 
     NORTH, SOUTH, EAST, WEST 
    }; 

    // This prevents any MashUpPlayer from trying to redefine the definition of 
    // object equality, which is important for the simulator to work properly. 
    public final boolean equals(Object other) { 
     return this == other; 
    } 
} 

Answer 1

Wizard() { 
    super("Some string", Color.Black); // default wizard values 
} 

Answer 2

試試這個。

import java.awt.*; 

public class Wizard extends MashUpPlayer { 

    static final String s = "^\u221e^"; 
    static final Color c = Color.GRAY; 

    Wizard() { 
     super(s, c); 
    } 

    public void setColor(Color c) { 
     super.setColor(c); 
    } 

    public void setDisplay(String s) { 
     super.setDisplay(s); 
    } 

    public Color getColor() { 
     return super.getColor(); 
    } 

    public String toString() { 
     return super.toString(); 
    } 

    ... 

} 

Answer 3

你的類繼承有點時髦。如果你想設置一些特定於兒童的行爲，你應該實現抽象方法並重寫其他的方法。從你發佈的代碼中，你不能直接訪問私有變量，而應該通過你沒有做的公共getter和setter來訪問它們。你甚至不能實例化你嘗試實例化的方式。您的s snd c無法在您的'MashUpPlayer'中訪問。你應該這樣做

MashUpPlayer player = new MashUpPlayer(); 
player.setColor(Color.GRAY);