Rectangle.java

Below is the syntax highlighted version of Rectangle.java from §3.2 Creating Data Types.

/******************************************************************************
 *  Compilation:  javac Rectangle.java
 *  Execution:    none
 *
 *  Immutable data type for axis-aligned rectangle.
 *
 ******************************************************************************/

/**
 *  The {@code Rectangle} class is an immutable data type to encapsulate a
 *  two-dimensional axis-aligned rectagle with real-value coordinates.
 *  The rectangle is <em>closed</em>—it includes the points on the boundary.
 *
 *  @author Robert Sedgewick
 *  @author Kevin Wayne
 */

public final class Rectangle {
    private final double xmin, ymin;   // minimum x- and y-coordinates
    private final double xmax, ymax;   // maximum x- and y-coordinates

    /**
     * Initializes a new rectangle [<em>xmin</em>, <em>xmax</em>]
     * x [<em>ymin</em>, <em>ymax</em>].
     *
     * @param  xmin the <em>x</em>-coordinate of the lower-left endpoint
     * @param  xmax the <em>x</em>-coordinate of the upper-right endpoint
     * @param  ymin the <em>y</em>-coordinate of the lower-left endpoint
     * @param  ymax the <em>y</em>-coordinate of the upper-right endpoint
     * @throws IllegalArgumentException if any of {@code xmin},
     *         {@code xmax}, {@code ymin}, or {@code ymax}
     *         is {@code Double.NaN}.
     * @throws IllegalArgumentException if {@code xmax < xmin} or {@code ymax < ymin}.
     */
    public Rectangle(double xmin, double ymin, double xmax, double ymax) {
        if (Double.isNaN(xmin) || Double.isNaN(xmax))
            throw new IllegalArgumentException("x-coordinate cannot be NaN");
        if (Double.isNaN(ymin) || Double.isNaN(ymax))
            throw new IllegalArgumentException("y-coordinates cannot be NaN");
        if (xmax < xmin || ymax < ymin) {
            throw new IllegalArgumentException("Invalid rectangle");
        }
        this.xmin = xmin;
        this.ymin = ymin;
        this.xmax = xmax;
        this.ymax = ymax;
    }

    /**
     * Returns the minimum <em>x</em>-coordinate of any point in this rectangle.
     *
     * @return the minimum <em>x</em>-coordinate of any point in this rectangle
     */
    public double xmin() {
        return xmin;
    }

    /**
     * Returns the maximum <em>x</em>-coordinate of any point in this rectangle.
     *
     * @return the maximum <em>x</em>-coordinate of any point in this rectangle
     */
    public double xmax() {
        return xmax;
    }

    /**
     * Returns the minimum <em>y</em>-coordinate of any point in this rectangle.
     *
     * @return the minimum <em>y</em>-coordinate of any point in this rectangle
     */
    public double ymin() {
        return ymin;
    }

    /**
     * Returns the maximum <em>y</em>-coordinate of any point in this rectangle.
     *
     * @return the maximum <em>y</em>-coordinate of any point in this rectangle
     */
    public double ymax() {
        return ymax;
    }

    /**
     * Returns the width of this rectangle.
     *
     * @return the width of this rectangle {@code xmax - xmin}
     */
    public double width() {
        return xmax - xmin;
    }

    /**
     * Returns the height of this rectangle.
     *
     * @return the height of this rectangle {@code ymax - ymin}
     */
    public double height() {
        return ymax - ymin;
    }

    /**
     * Returns true if the two rectangles intersect.
     *
     * @param  that the other rectangle
     * @return {@code true} if this rectangle intersect the argument
               rectagnle at one or more points, including on the boundary
     */
    public boolean intersects(Rectangle that) {
        return this.xmax >= that.xmin && this.ymax >= that.ymin
            && that.xmax >= this.xmin && that.ymax >= this.ymin;
    }

    /**
     * Returns true if this rectangle contain the rectangle.
     * @param  rect the rectangle
     * @return {@code true} if this rectangle contain the rectangle {@code rect},
               possibly at the boundary; {@code false} otherwise
     */
    public boolean contains(Rectangle rect) {
        return (rect.xmin >= xmin) && (rect.xmax <= xmax)
            && (rect.ymin >= ymin) && (rect.ymax <= ymax);
    }

    /**
     * Compares this rectangle to the specified rectangle.
     *
     * @param  other the other rectangle
     * @return {@code true} if this rectangle equals {@code other};
     *         {@code false} otherwise
     */
    @Override
    public boolean equals(Object other) {
        if (other == this) return true;
        if (other == null) return false;
        if (other.getClass() != this.getClass()) return false;
        Rectangle that = (Rectangle) other;
        if (this.xmin != that.xmin) return false;
        if (this.ymin != that.ymin) return false;
        if (this.xmax != that.xmax) return false;
        if (this.ymax != that.ymax) return false;
        return true;
    }

    /**
     * Returns an integer hash code for this rectangle.
     * @return an integer hash code for this rectangle
     */
    @Override
    public int hashCode() {
        int hash1 = ((Double) xmin).hashCode();
        int hash2 = ((Double) ymin).hashCode();
        int hash3 = ((Double) xmax).hashCode();
        int hash4 = ((Double) ymax).hashCode();
        return 31*(31*(31*hash1 + hash2) + hash3) + hash4;
    }

    /**
     * Returns a string representation of this rectangle.
     *
     * @return a string representation of this rectangle, using the format
     *         {@code [xmin, xmax] x [ymin, ymax]}
     */
    @Override
    public String toString() {
        return "[" + xmin + ", " + xmax + "] x [" + ymin + ", " + ymax + "]";
    }

    /**
     * Draws this rectangle to standard draw.
     */
    public void draw() {
        StdDraw.line(xmin, ymin, xmax, ymin);
        StdDraw.line(xmax, ymin, xmax, ymax);
        StdDraw.line(xmax, ymax, xmin, ymax);
        StdDraw.line(xmin, ymax, xmin, ymin);
    }


}