有没有一种方法可以重用我的部分代码，这些代码做同样的事情但访问 Java 类的不同属性？

Question

So I was doing a program there's supposed to verify if when cut, a triangle can produce two new triangles, I did all the logic and the code works just as it is supposed to, however as I was doing I noticed that I had to apply the same logic for different attributes over and over again, which seemed highly unproductive. Here's the code:

public static class Triangle{
        private int[] x = new int[3];
        private int[] y = new int[3];
    
        public int getX(int position) {
            return x[position];
        }
        public int getY(int position) {
            return y[position];
        }
        
        //Get the information regarding the points that make the triangle
        public void setDomains(Scanner readVar){     
            readVar.nextLine();
            this.x[0] = readVar.nextInt();
            this.y[0] = readVar.nextInt();
            this.x[1] = readVar.nextInt();
            this.y[1] = readVar.nextInt();
            this.x[2] = readVar.nextInt();
            this.y[2] = readVar.nextInt();
            
        }

        //Verify if one of the other points is lower or higher than the present one
        public boolean areDiffX(int i, int j, boolean isLower){
 
            if(isLower){
                if(this.getX(i) < this.getX(j)){
                    return true;
                };
            }else{
                if(this.getX(i) > this.getX(j)){
                    return true;
                };
            }
     
            return false;
        }
        //Verify if one of the other points is lower or higher than the present one
        public boolean areDiffY(int i, int j, boolean isLower){
     
            if(isLower){
                if(this.getY(i) < this.getY(j)){
                    return true;
                };
            }else{
                if(this.getY(i) > this.getY(j)){
                    return true;
                };
            }
     
            return false;
        }
    
        //Verify if from the X axes two new triangles can ensurge
        public boolean compareTriangleDomain(int i, int j, int k){
    
            boolean hasDomain = false;
            boolean hasCodomain = false;
    
            hasDomain = areDiffX(i, j, true);
            hasCodomain = areDiffX(i, k, false);
            if(hasDomain == true && hasCodomain == true){
                return true;
            }
     
            hasDomain = areDiffX(i, j, false);
            hasCodomain = areDiffX(i, k, true);
            if(hasDomain == true && hasCodomain == true){
                return true;
            }
    
            return false;
        }
        
        //Verify if from the Y axes two new triangles can ensurge
        public boolean compareTriangleCodomain(int i, int j, int k){
    
            boolean hasDomain = false;
            boolean hasCodomain = false;
    
            hasDomain = areDiffY(i, j, true);
            hasCodomain = areDiffY(i, k, false);
            if(hasDomain == true && hasCodomain == true){
                return true;
            }
     
            hasDomain = areDiffY(i, j, false);
            hasCodomain = areDiffY(i, k, true);
            if(hasDomain == true && hasCodomain == true){
                return true;
            }
     
            return false;
        }
        
        //Verify if from a certain point of a triangle can be produced two new triangles
        public boolean cutTriangle(int i, int j, int k){
     
           boolean halveTriangleX = compareTriangleDomain(i, j, k);
           boolean halveTriangleY = compareTriangleCodomain(i, j, k);
           if(halveTriangleX || halveTriangleY){
                return true;
           }
           return false;
     
        }

        //Verify if a triangle can produce two new triangles
        public void checkCut(){

            boolean canCut = false;
            boolean hasntCut = true;

            canCut = cutTriangle(0, 1, 2);
            if(canCut == true && hasntCut == true){
                System.out.println("YES");
                hasntCut = false;
            }
            canCut = cutTriangle(1, 0, 2);
            if(canCut == true && hasntCut == true){
                System.out.println("YES");
                hasntCut = false;
            }
            canCut = cutTriangle(2, 1, 0);
            if(canCut == true && hasntCut == true){
                System.out.println("YES");
            }
            else if(hasntCut == true){
                System.out.println("NO");
            }
           
        }
    }

I thought that maybe I could add a new parameter to the get function so to specify which axes I'm working with, but I don't know if this a dumb way to do it, any recommendations and advices are welcome I'm still a baby in java and coding in general.

Answer 1

There are a few ways to do this. I would go with simply writing a function which takes the values instead of the indices, and then two new functions which get the values:

public boolean areDiff(int a, int b, boolean isLower){
  if (isLower) {
    if (a < b) {
      return true;
    }
  } else {
    if (a > b) {
      return true;
    }
  }     
  return false;
}

and then:

public boolean areDiffX(int i, int j, boolean isLower){
   return areDiff(this.getX(i), this.getX(j), isLower);
}

and a similar areDiffY function.

You can rewrite compareTriangleDomain to take values and use areDiff and dispense with compareTriangleCodomain and areDiffX/Y .

Answer 2

Perhaps I dug too deep, but I want to suggest the following approach.

The triangle obviously consists of three points on the plane. Why not make a class to represent the point? I will use the record syntax that appeared in Java 14. I also add two methods for comparing points and two comparators. One allows you to compare points by x coordinate, the second by y .

import java.util.Comparator;
import java.util.function.ToIntFunction;

public record Point2D(int x, int y) {

    private static Comparator<Point2D> compareBy(ToIntFunction<Point2D> keyExtractor) {
        return (o1, o2) -> Comparator.comparingInt(keyExtractor).compare(o1, o2);
    }

    public static Comparator<Point2D> byX = compareBy(Point2D::x);
    public static Comparator<Point2D> byY = compareBy(Point2D::y);

    public boolean less(Point2D other, Comparator<Point2D> comp) {
        return comp.compare(this, other) < 0;
    }

    public boolean higher(Point2D other, Comparator<Point2D> comp) {
        return comp.compare(this, other) > 0;
    }
}

Now we can greatly simplify the Triangle class. The triangle is represented by an array of three points instead of six integers.

private final Point2D[] vertices = new Point2D[3];

public void setDomains(Scanner readVar) {
    readVar.nextLine();
    this.vertices[0] = new Point2D(readVar.nextInt(), readVar.nextInt());
    this.vertices[1] = new Point2D(readVar.nextInt(), readVar.nextInt());
    this.vertices[2] = new Point2D(readVar.nextInt(), readVar.nextInt());
}

And all other methods look like this

public boolean compareTriangle(int i, int j, int k, Comparator<Point2D> comp) {  
    boolean hasDomain;                                                             
    boolean hasCodomain;                                                           
                                                                                   
    hasDomain = vertices[i].less(vertices[j], comp);                               
    hasCodomain = vertices[i].higher(vertices[k], comp);                           
    if (hasDomain && hasCodomain) {                                                
        return true;                                                               
    }                                                                              
                                                                                   
    hasDomain = vertices[i].higher(vertices[j], comp);                             
    hasCodomain = vertices[i].less(vertices[k], comp);                             
    return hasDomain && hasCodomain;                                               
}                                                                                  
                                                                                   
public boolean cutTriangle(int i, int j, int k) {                                  
    boolean halveTriangleX = compareTriangle(i, j, k, Point2D.byX);              
    boolean halveTriangleY = compareTriangle(i, j, k, Point2D.byY);              
    return halveTriangleX || halveTriangleY;                                       
}                                                                                  

I have not tested this code (in my opinion it is identical to yours), so you should definitely check it out.