如何使用toString方法將我的座標轉換爲向左下方

Question

我希望toString()返回[up, down, right,left]而不是整數。例如，

new Direction(-1,1).toString() should give "<up right>". 
new Direction(1,-1).toString() should give "<down left>" 
new Direction(1,0).toString() should give "<down>" 
new Direction(0,-1).toString() should give "<left>" 

Answer 1

既然你要重寫你的方向類的toString（）方法，也爲你的問題的緣故，讓Direction.x和Direction.y是你的方向類中的一些變量（你的問題陳述從未指定），你可以去這樣

@Override 
public String toString() 
{ 
    // Testing for (-1 , 1) 
    if(this.x < 0 && this.y > 0) 
    { 
     return "<up right>"; 
    } 
    // Testing for (1 , -1) 
    else if(this.x > 0 && this.y < 0) 
    { 
     return "<down left>"; 
    } 
    // Testing for (1 , 0) 
    else if(this.x > 0 && this.y == 0) 
    { 
     return "<down>"; 
    } 
    // Since none of the above executed, we assume that it's (0 , -1) case 
    else 
    { 
     return "<up>"; 
    } 

} 

所以最後真的是你的方向類必須是這個樣子才能正常工作

public class Direction 
{ 
    // You are pretty new so I wouldn't confuse you with public,protected and private here 
    public int x; 
    public int y; 

    public Direction(int xArg , int yArg) 
    { 
     this.x = xArg; 
     this.y = yArg; 
    } 

    public Direction() // No-Arg Constructor, give default values here 
    { 
     // this could really be initialized to fit your taste 
     this.x = -1; 
     this.y = 1; 
    } 

    @Override 
    public String toString() 
    { 
     // Testing for (-1 , 1) 
     if(this.x < 0 && this.y > 0) 
     { 
      return "<up right>"; 
     } 
     // Testing for (1 , -1) 
     else if(this.x > 0 && this.y < 0) 
     { 
      return "<down left>"; 
     } 
     // Testing for (1 , 0) 
     else if(this.x > 0 && this.y == 0) 
     { 
      return "<down>"; 
     } 
     // Since none of the above executed, we assume that it's (0 , -1) case 
     else 
     { 
      return "<up>"; 
     } 

    } 
} 

我真的不能告訴你如何讓你理解一個非常基本的if-else-if流，但是在將這些代碼放在Direction類中並知道有一些int變量x和y後，調用new Direction（-1 ，1）.toString（）;new Direction（1，-1）.toString（）;new Direction（1,0）.toString（）;和新的方向（0，-1）.toString（）會給你適當的結果;