java使用枚举构建象限

Question

出于某种原因，我将结束这个问题

Answer 1

通过将基本属性作为属性传递给每个枚举，可以减少代码量signPair使用一些基本的算术属性来计算翻转象限的序号

public enum Quadrant { 
  Q1(true,true),
  Q2(false, true),
  Q3(false, false),
  Q4(true, false);

  private boolean xpos;
  private boolean ypos;
  Quadrant( boolean xpos, boolean ypos ){
    this.xpos = xpos;
    this.ypos = ypos;
  }
  public boolean xPositive(){
    return xpos;
  }
  public boolean yPositive(){
    return ypos;
  }
  public String signPair(){
    return "(" + (xpos ? "+" : "-") + "," + (ypos ? "+" : "-") + ")";
  }
  public Quadrant flipX(){
    return values()[ordinal() + 1 - 2*(ordinal()%2)];
  }
  public static Quadrant fromInts(int x, int y){
    if( x >= 0 ){
      return y >= 0 ? Quadrant.Q1 : Quadrant.Q4;
    } else {
      return y >= 0 ? Quadrant.Q2 : Quadrant.Q3;
    }
  }
}

还可以为每个枚举定义方法：

public enum Quadrant { 
  Q1(true,true){
    public Quadrant flipX(){ return Quadrant.Q2; }
    public String signPair(){ return "(+,+)"; }
  },
  Q2(false, true){
    public Quadrant flipX(){ return Quadrant.Q1; }
    public String signPair(){ return "(-,+)"; }
  },
  Q3(false, false){
    public Quadrant flipX(){ return Quadrant.Q4; }
    public String signPair(){ return "(-,-)"; }
  },
  Q4(true, false){
    public Quadrant flipX(){ return Quadrant.Q3; }
    public String signPair(){ return "(+,-)"; }
  };
  //...
  public abstract String signPair();
  public abstract Quadrant flipX();
  //...
}

这里有一个测试：

public static void main(String[] args) {
  for( Quadrant q: Quadrant.values() ){
    System.out.println( q );
    System.out.println( q.xPositive() );
    System.out.println( q.yPositive() );
    System.out.println( q.signPair() );
    System.out.println( q.flipX() );
  }
  for( int x = -1; x <= 1; ++x ){
    for( int y = -1; y <= 1; ++y ){
      System.out.println( Quadrant.fromInts(x, y) );
    }
  }
}

要运行所需的主进程参数，请执行以下操作：

 public static void main(String[] args) {
   for( int i = 2; i <= args.length; i++ ){
      int x = Integer.parseInt( args[i-2] );
      int y = Integer.parseInt( args[i-1] );
      Quadrant q = Quadrant.fromInts(x, y);
      System.out.println("( + x + "," + y + ") in " + q + " " + q.signPair());
   }
 }