hello everyone...
I'm new in java and is currently studying about collections...
I'm trying to make my own collection package so that I would understand more about the functions of the collection classes and interfaces....
I'm currently making my own HashSet class and I have a problem about preventing duplicates...here the code...
Code:
// The IMySet interface has the following abstract method(s)
// public void clear();
// public void remove(Object obj);
// and implements the IMyCollection interface and here are its abstract method(s)
// public void add(Object obj)
// public void add(IMyCollection collection)
// here's my code for my custom HashSet class[/B]
public class CMyHashSet implements IMySet {
// attribute(s)
private Object[] object;
private boolean[] isShown;
private int counter;
// constructor(s)
public CMyHashSet() {
object = new Object[16];
isShown = new boolean[16];
} // close CMyHashSet()
// implemented method(s)
public void add(Object obj) {
if ( addObject(obj) ) {
object[counter] = obj;
isShown[counter] = true;
counter++;
} // close if (...)
} // close add(Object)
public void add(IMyCollection collection) {
if ( addObject(collection) ) {
object[counter] = collection;
isShown[counter] = true;
counter++;
} // close if (...)
} // close add(Collection)
public void remove(Object obj) {
// haven't done yet
} // close remove(Object)
public void clear() {
object = new Object[16];
isShown = new boolean[16];
counter = 0;
} // close clear()
public String toString() {
StringBuffer my_string = new StringBuffer();
my_string.append( '<' );
for (int i = 0; i < object.length; i++) {
if ( isShown[i] ) {
my_string.append( object[i] );
if ( i < countIsShown() - 1 ) {
my_string.append( ", " );
} // close if (...)
} // close if (...)
} // close for (...)
my_string.append( '>' );
return ( my_string.toString() );
} // close toString()
// other method(s)
// count how many true values isShown[] has
private int countIsShown() {
int numOfTrueValue = 0;
for (int i = 0; i < isShown.length; i++) {
if ( isShown[i] ) {
numOfTrueValue++;
} // close if (...)
} // close for (...)
return ( numOfTrueValue );
} // close countIsShown()
// checks if an Object has duplicates with
// one of the Objects of the object[]
private boolean addObject(Object obj) {
boolean isAdded = true;
for (int i = 0; i < object.length; i++) {
if ( object[i] != null &&
object[i].hashCode() == obj.hashCode() ) {
isAdded = false;
break;
} // close if (...)
} // close for (...)
return ( isAdded );
} // close addObject(Object)
} // close CMyHashSet class
my problem is that my custom HashSet class doesn't let null values in the object[]...does anyone has a suggestion on what I should do?...tnx...[/B]
creating your own HashSet class
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