改變點的方向

Question

我想創建一個模擬機器人功能的代碼。轉動和移動等。我感覺好像我以各種錯誤的方式來處理這個問題......當我寫這篇文章時，我認爲我理解了它的要旨，如果構造函數中的方向是這樣的，那麼如果它轉向新的方向就是這樣。我測試了這一點，當然，我最終得到了一些真正不正確的結果。我絕對相信我實際上並沒有爲我的對象使用這些函數。我可以得到關於如何使用這種代碼的提示嗎？

import java.awt.Point; 
public class Robot 
{ 
private int x; 
private int y; 
private int d; 
private int p; 
public static final int NORTH = 0; 
public static final int SOUTH = 1; 
public static final int EAST = 2; 
public static final int WEST = 3; 

/** 
* Constructor for objects of class Robot 
* @param theX the x coordinate 
* @param theY the y coordinate 
* @param theDirection the direction the robot is facing 
*/ 
public Robot(int theX, int theY, int theDirection) 
{ 
    x = theX; 
    y = theY; 
    d = theDirection; 
} 

public void turnLeft() 
{ 
    if(d == NORTH) { 
     d = WEST; 
    } 
    if(d == WEST) { 
     d = SOUTH; 
    } 
    if(d == SOUTH) { 
     d = EAST; 
    } 
    if(d == EAST) { 
     d = NORTH; 
    } 
} 



public String getDirection() 
{ 
    if(d == NORTH) { 
     return "N"; 
    } 
    if(d == SOUTH) { 
     return "S"; 
    } 
    if(d == WEST) { 
     return "W"; 
    } 
    if(d == EAST) { 
     return "E"; 
    } 
    return ""; 
} 
} 

測試

Robot rob = new Robot(20, 20, Robot.SOUTH); 
rob.turnLeft; 
System.out.println(rob.getDirection); 

這回當我想起它實際上應該返回E.

Answer 1

什麼是p VAR您使用？ 您當前的方向是存儲在d

... 
d = theDirection; 
... 

你應該與這一個嘗試：

public void turnLeft() 
{ 
    if(d == NORTH) { 
     d = WEST; 
    } 
    if(d == WEST) { 
     d = SOUTH; 
    } 
    if(d == SOUTH) { 
     d = EAST; 
    } 
    if(d == EAST) { 
     d = NORTH; 
    } 
} 

編輯： 只是爲了澄清。

你寫的東西像

if(p == SOUTH) { 
     d = EAST; 
    } 

所以你檢查是否p是南部和不d。

你沒有在任何地方使用p所以它永遠不會是南方，這就是爲什麼你的turnLeft()方法絕對沒有什麼！

Answer 2

你需要別的如果。當您左轉時，您爲d指定一個新值，它與以下if語句的條件相匹配。

Answer 3

您的turnLeft方法不太正確。
下面的代碼使用if：

public void turnLeft() { 
    if (d == NORTH) { 
     d = WEST; 
    } else if (d == WEST) { 
     d = SOUTH; 
    } else if (d == SOUTH) { 
     d = EAST; 
    } else if (d == EAST) { 
     d = NORTH; 
    } 
} 

這裏的使用switch..case

public void turnLeft() { 

    switch (d) { 
    case NORTH: d = WEST; break; 
    case WEST: d = SOUTH; break; 
    case SOUTH: d = EAST; break; 
    case EAST: d = NORTH; break; 
    } 
} 

Answer 4

1的代碼）你真的應該清理您的p和d的東西;）我建議叫d「方向「

2nd）你應該重新排列你的int常量順時針順序的方向。所以你可以將你的turnLeft()方法減少爲一行代碼。測試你應該使用JUnit

public static final int NORTH = 0; 
public static final int EAST = 1; 
public static final int SOUTH = 2; 
public static final int WEST = 3; 

3）：

@Test 
public void turnLeft() { 
    Robot rob = new Robot(20, 20, Robot.SOUTH); 
    rob.turnLeft; 
    assertEquals("E", rob.getDirection); 
    rob.turnLeft; 
    assertEquals("N", rob.getDirection); 
    rob.turnLeft; 
    assertEquals("W", rob.getDirection); 
    rob.turnLeft; 
    assertEquals("S", rob.getDirection); 
} 

Answer 5

public void turnLeft() 
{ 
    if(d == NORTH) { 
     d = WEST; 
    } 
    else if(d == WEST) { 
     d = SOUTH; 
    } 
    else if(d == SOUTH) { 
     d = EAST; 
    } 
    else if(d == EAST) { 
     d = NORTH; 
    } 
} 

因爲如果d == NORTH，然後d將成爲WEST你可以命令他們這樣。

而且在未來，如果，d的確會d==WEST，並將成爲SOUTH。

，並在一天結束時，d將再次NORTH。

Answer 6

枚舉

public enum Direction { 
    private String name; 
    private String indicator; 

    public Direction(String name, String indicator) { 
     this.name = name; 
     this.indicator= indicator; 
    } 

    // getters 

    NORTH("North", "N"), 
    EAST("East", "E"), 
    SOUTH("South", "S"), 
    WEST("West", "W"); 
} 

接下來，你可以很容易地做到這一點：

turnLeft() { 
    switch (d) { 
     case Direction.NORTH: return Direction.WEST; 
     case Direction.WEST: return Direction.SOUTH; 
     case Direction.SOUTH: return Direction.EAST; 
     case Direction.EAST: return Direction.NORTH; 
    } 
} 

getDirection() { 
    return d.getIndicator(); 
} 

這樣你就可以擺脫四個靜態的int（NORTH，WEST，EAST，SOUTH）和變化int d分成Direction d。我真的會推薦使用這個enum。只是爲了安全。