How can I see if two rectangles have one equal point using java?

Question

I have rectangle A = upper left point (-4,-1), bottom right point (-2-2) and rectangle B upper left point (-2,-2), bottom right point (-1,-3)

then:

Rectangle first = new Rectangle(-4,-1,2,1);  //x1,y1,width,height
Rectangle second = new Rectangle(-2,-2,1,1);

OK, I have 2 rectangles with 1 same point. I use first.intersects(second) and this returns false..

How can I use java to do this, I need something return True if One point or more into Rectangle A belongs Rectangle B?

My code now:

public class GeometriaRectangle2 {

public static void main(String[] args) {
    Scanner lector = new Scanner(System.in);
    while (lector.hasNextLine()) {
        String a[] = lector.nextLine().split(",");
        int b[] = new int[a.length];

        for (int i = 0; i < a.length; i++) {
            b[i] = Integer.parseInt(a[i]);
        }
        int c = Math.abs(b[0] - b[2]);
        int d = Math.abs(b[1] - b[3]);
        int e = Math.abs(b[4] - b[6]);
        int f = Math.abs(b[5] - b[7]);
        Rectangle r = new Rectangle(b[0], b[1], c, d);
        Rectangle r2 = new Rectangle(b[4], b[5], e, f);
        int tw = r.width;
        int th = r.height;
        int rw = r2.width;
        int rh = r2.height;
        if (rw <= 0 || rh <= 0 || tw <= 0 || th <= 0) {
            System.out.println(false);
        }
        int tx = r.x;
        int ty = r.y;
        int rx = r2.x;
        int ry = r2.y;
        rw += rx;
        rh += ry;
        tw += tx;
        th += ty;
        // overflow || intersect or attached
        if ((rw < rx || rw >= tx) && (rh < ry || rh >= ty)
                && (tw < tx || tw >= rx) && (th < ty || th >= ry)) {
            System.out.println(true);
        } else {
            System.out.println(false);
        }
    }
}

}

Example: input:

-3,3,-1,1,1,-1,3,-3

-3,3,-1,1,-2,4,2,2

output:

False

True

Yohanes Khosiawan 许先汉 · Accepted Answer

You may also modifies the current code of intersects function to suit your needs. In your case you want to state it true when there is a pair of points from two rectangles (even the side line's) are sharing the same coordinate - (read: attached). Thus, you may try something like this:

public boolean intersectsOrAttached(Rectangle r, Rectangle r2) {
    int tw = r.width;
    int th = r.height;
    int rw = r2.width;
    int rh = r2.height;
    if (rw <= 0 || rh <= 0 || tw <= 0 || th <= 0) {
        return false;
    }

    int tx = r.x;
    int ty = r.y;
    int rx = r2.x;
    int ry = r2.y;
    rw += rx;
    rh += ry;
    tw += tx;
    th += ty;

    //overflow || intersect or attached
    return ((rw < rx || rw >= tx) &&
        (rh < ry || rh >= ty) &&
        (tw < tx || tw >= rx) &&
        (th < ty || th >= ry));
}

UPDATE:

Actually online judging system is a little bit tricky. I managed to get it accepted partially, I'm not sure whether it's time or memory constraints, as well as some overlooked bound-cases that we couldn't figure out easily. But here it is, it's better if you can make it optimized by yourself:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class OverlappingRectangles {

    public static void main(String[] args) {
        String f = args[0];
        try {
            BufferedReader br = new BufferedReader(new FileReader(f));
            while (br.ready()) {
                String cs[] = br.readLine().split(",");
                int[] ci = new int[cs.length];
                int i = 0;
                for (String s : cs) {
                    ci[i] = Integer.parseInt(s);
                    i += 1;
                }

                if (ck(ci[0], ci[1], ci[2], ci[3], ci[4], ci[5], ci[6], ci[7])) {
                    System.out.println("True");
                } else {
                    System.out.println("False");
                }
            }
        } catch (FileNotFoundException ex) {
        } catch (IOException ex) {
        }
    }

    public static boolean ck(int rx, int ry, int rw, int rh, int tx, int ty, int tw, int th) {
        //ATTENTION!
        //rx,ry -> upper-left corner of rect A
        //rw,rh -> bottom-right corner of rect A
        //tx,ty -> upper-left corner of rect B
        //tw,th -> bottom-right corner of rect B
        return ((rw < rx || rw >= tx)
                && (rh < ry || rh >= ty)
                && (tw < tx || tw >= rx)
                && (th < ty || th >= ry));
    }
}

How can I see if two rectangles have one equal point using java?

Answers (2)

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