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null NOT permitted). * @param y the y-value (null permitted). */ public ComparableObjectItem(Comparable x, Object y) { if (x == null) { throw new IllegalArgumentException("Null 'x' argument."); } this.x = x; this.obj = y; } /** * Returns the x-value. * * @return The x-value (never null). */ protected Comparable getComparable() { return this.x; } /** * Returns the y-value. * * @return The y-value (possibly null). */ protected Object getObject() { return this.obj; } /** * Sets the y-value for this data item. Note that there is no * corresponding method to change the x-value. * * @param y the new y-value (null permitted). */ protected void setObject(Object y) { this.obj = y; } /** * Returns an integer indicating the order of this object relative to * another object. * * For the order we consider only the x-value: * negative == "less-than", zero == "equal", positive == "greater-than". * * @param o1 the object being compared to. * * @return An integer indicating the order of this data pair object * relative to another object. */ public int compareTo(Object o1) { int result; // CASE 1 : Comparing to another ComparableObjectItem object // --------------------------------------------------------- if (o1 instanceof ComparableObjectItem) { ComparableObjectItem that = (ComparableObjectItem) o1; return this.x.compareTo(that.x); } // CASE 2 : Comparing to a general object // --------------------------------------------- else { // consider these to be ordered after general objects result = 1; } return result; } /** * Returns a clone of this object. * * @return A clone. * * @throws CloneNotSupportedException not thrown by this class, but * subclasses may differ. */ public Object clone() throws CloneNotSupportedException { return super.clone(); } /** * Tests if this object is equal to another. * * @param obj the object to test against for equality (null * permitted). * * @return A boolean. */ public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof ComparableObjectItem)) { return false; } ComparableObjectItem that = (ComparableObjectItem) obj; if (!this.x.equals(that.x)) { return false; } if (!ObjectUtilities.equal(this.obj, that.obj)) { return false; } return true; } /** * Returns a hash code. * * @return A hash code. */ public int hashCode() { int result; result = this.x.hashCode(); result = 29 * result + (this.obj != null ? this.obj.hashCode() : 0); return result; } } ...展开收缩