构造函数创建多个变量，如何通过其他方法返回？

Question

public class Game {

    public Game(
        boolean createstage, //For sorting purposes
        int slength, 
        int sheight, 
        boolean createplayer, 
        int plength, 
        int pheight, 
        boolean playersprite,
        BufferedImage psprite, 
        boolean defaultcontrols,
        String pcontrols, 
        boolean test
        ) {
    if(test == true) { //if test is true, test
        new Test();
    }else{ //otherwise create a stage is createstage is true and
        if(createstage == true) {
            StageObj gamestage = new StageObj(slength, sheight);
        }
        if(createplayer==true) {
            PlayerObj player = new PlayerObj(plength, pheight, psprite, pcontrols);
        }
    }
}

public Game() {
    new StageObj(100, 100);
    new PlayerObj(10, 10);
}

public StageObj givestageobj() {
    return gamestage;
}

public PlayerObj giveplayerobj() {
    return player;
}

}

我的构造函数的代码和设计用于返回构造函数中创建的变量的两个变量也是如此。问题是方法 giveplayerobj 和 givestageobj 都没有找到变量 gamestage 和 player。这是有道理的，但是我如何在构造函数中创建变量，然后以某种方式将它们传递给 giveplayerobj() 和 givestageobj() 变量，这样理论上有人可以去 Game.giveplayerobj() 返回构造函数中创建的 playerobj？

谢谢

-JXP

Answer 1

您需要将它们声明为类属性，而不是在构造函数中才能使其工作。因此，您的代码应该如下所示。

变化：

1. 我添加了两个类变量 StageObj 和PlayerObj，因为您已经为它们准备好了吸气剂。
2. 从构造函数中删除了这两个变量的声明。

3. 为覆盖的默认构造函数添加了赋值。 （可能是您尝试使用默认构造函数实现的目标）

   public class Game {
   
   private StageObj gamestage = null;
   private PlayerObj player = null;
   
   public Game(
       boolean createstage, //For sorting purposes
       int slength, 
       int sheight, 
       boolean createplayer, 
       int plength, 
       int pheight, 
       boolean playersprite,
       BufferedImage psprite, 
       boolean defaultcontrols,
       String pcontrols, 
       boolean test
       ) {
   if(test == true) { //if test is true, test
       new Test();
   }else{ //otherwise create a stage is createstage is true and
       if(createstage == true) {
           gamestage = new StageObj(slength, sheight);
       }
       if(createplayer==true) {
           player = new PlayerObj(plength, pheight, psprite, pcontrols);
       }
   }
   }
   
   public Game() {
       gamestage = new StageObj(100, 100);
       player = new PlayerObj(10, 10);
   }
   
   public StageObj givestageobj() {
       return gamestage;
   }
   
   public PlayerObj giveplayerobj() {
       return player;
   }
   
   }
   

Answer 2

变量gamestage 和player 都需要是实例变量：

public class Game {
     private StageObj gamestage;
     private PlayerObj player;

(...) - and in the constructor :

        if(createstage == true) {
            gamestage = new StageObj(slength, sheight);
        }
        if(createplayer==true) {
            player = new PlayerObj(plength, pheight, psprite, pcontrols);
        }

(...)

}

Answer 3

我认为你想要的是一个实例变量，即

public class Game {
  private StageObj gamestage;
  ...
  public Game(...) { ... }      

  public StageObj givestageobj() {
    return gamestage;
  }
}

Answer 4

你需要在构造函数之前设置你的数据字段，并像这样使用 getter en setter 方法：

public class Game {

private StageObj gamestage = null;
private PlayerObj player = null;

public Game(
    boolean createstage, //For sorting purposes
    int slength, 
    int sheight, 
    boolean createplayer, 
    int plength, 
    int pheight, 
    boolean playersprite,
    BufferedImage psprite, 
    boolean defaultcontrols,
    String pcontrols, 
    boolean test
    ) {
if(test == true) { //if test is true, test
    new Test();
}else{ //otherwise create a stage is createstage is true and
    if(createstage == true) {
        gamestage = new StageObj(slength, sheight);
    }
    if(createplayer==true) {
        player = new PlayerObj(plength, pheight, psprite, pcontrols);
    }
}
}

public Game() {
    gamestage = new StageObj(100, 100);
    player = new PlayerObj(10, 10);
}

public StageObj givestageobj() {
    return gamestage;
}

public PlayerObj giveplayerobj() {
    return player;
}

}


public Game() {
new StageObj(100, 100);
new PlayerObj(10, 10);
}

public StageObj givestageobj() {
return gamestage;
}

public PlayerObj giveplayerobj() {
return player;
}

public int getSlenght(){
return slenght;
}

public void setSlenght(int slenght){
this.slenght = slenght;
}

}

等等当然你需要添加其他类，而不是在一个类中做所有事情。您需要一个 Player 和 Stage 类 ;-) 还可以查看 Oracle 的 Java 课程http://docs.oracle.com/javase/tutorial/java/javaOO/