Uma contribuição para quem tiver o interesse ou para sente dificuldade em trabalhar com listas dinâmicas … clássica transição do J2EE ou mesmo J2SE para o J2ME … ehehehe
[code]public class ArrayList {
private Object[] storedObjects;
private int growthFactor;
private int size;
public ArrayList() {
this( 10, 75 );
}
public ArrayList( int initialCapacity ) {
this( initialCapacity, 75 );
}
public ArrayList( int initialCapacity, int growthFactor ) {
this.storedObjects = new Object[ initialCapacity ];
this.growthFactor = growthFactor;
}
public int size() {
return this.size;
}
public boolean contains( Object element ) {
if (element == null) {
throw new IllegalArgumentException( "ArrayList cannot contain a null element.");
}
for (int i = 0; i < this.size; i++) {
Object object = this.storedObjects[i];
if ( object.equals( element ) ) {
return true;
}
}
return false;
}
public int indexOf(Object element) {
if (element == null) {
throw new IllegalArgumentException( "ArrayList cannot contain a null element.");
}
for (int i = 0; i < this.size; i++) {
Object object = this.storedObjects[i];
if ( object.equals( element ) ) {
return i;
}
}
return -1;
}
public Object get( int index ) {
if (index < 0 || index >= this.size ) {
throw new IndexOutOfBoundsException("the index [" + index + "] is not valid for this list with the size [" + this.size + "].");
}
return this.storedObjects[ index ];
}
public Object remove( int index ) {
if (index < 0 || index >= this.size ) {
throw new IndexOutOfBoundsException("the index [" + index + "] is not valid for this list with the size [" + this.size + "].");
}
Object removed = this.storedObjects[ index ];
for (int i = index+1; i < this.size; i++) {
this.storedObjects[ i-1 ] = this.storedObjects[ i ];
}
this.size--;
this.storedObjects[ this.size ] = null;
return removed;
}
public boolean remove( Object element ) {
if (element == null) {
throw new IllegalArgumentException( "ArrayList cannot contain null.");
}
int index = -1;
for (int i = 0; i < this.size; i++) {
Object object = this.storedObjects[i];
if ( object.equals( element ) ) {
index = i;
break;
}
}
if (index == -1) {
return false;
}
for (int i = index+1; i < this.size; i++) {
this.storedObjects[ i-1 ] = this.storedObjects[ i ];
}
this.size--;
this.storedObjects[ this.size ] = null;
return true;
}
public void clear() {
for (int i = 0; i < this.size; i++) {
this.storedObjects[i] = null;
}
this.size = 0;
}
public void add( Object element) {
if (element == null) {
throw new IllegalArgumentException( "ArrayList cannot contain null.");
}
if (this.size >= this.storedObjects.length) {
increaseCapacity();
}
this.storedObjects[ this.size ] = element;
this.size++;
}
public void add( int index, Object element ) {
if (element == null) {
throw new IllegalArgumentException( "ArrayList cannot contain null.");
}
if (index < 0 || index > this.size ) {
throw new IndexOutOfBoundsException("the index [" + index + "] is not valid for this list with the size [" + this.size + "].");
}
if (this.size >= this.storedObjects.length) {
increaseCapacity();
}
// shift all following elements one position to the back:
for (int i = this.size; i > index; i--) {
this.storedObjects[i] = this.storedObjects[ i-1 ];
}
// insert the given element:
this.storedObjects[ index ] = element;
this.size++;
}
public Object set( int index, Object element ) {
if (index < 0 || index >= this.size ) {
throw new IndexOutOfBoundsException("the index [" + index + "] is not valid for this list with the size [" + this.size + "].");
}
Object replaced = this.storedObjects[ index ];
this.storedObjects[ index ] = element;
return replaced;
}
public String toString() {
StringBuffer buffer = new StringBuffer( this.size * 23 );
buffer.append( super.toString() ).append( "{\n" );
for (int i = 0; i < this.size; i++) {
buffer.append( this.storedObjects[i] );
buffer.append('\n');
}
buffer.append('}');
return buffer.toString();
}
public Object[] toArray() {
Object[] copy = new Object[ this.size ];
System.arraycopy( this.storedObjects, 0, copy, 0, this.size );
return copy;
}
public Object[] toArray( Object[] target ) {
System.arraycopy( this.storedObjects, 0, target, 0, this.size );
return target;
}
public void trimToSize() {
if (this.storedObjects.length != this.size ) {
Object[] newStore = new Object[ this.size ];
System.arraycopy( this.storedObjects, 0, newStore, 0, this.size );
this.storedObjects = newStore;
}
}
private void increaseCapacity() {
int currentCapacity = this.storedObjects.length;
int newCapacity = currentCapacity + ((currentCapacity * this.growthFactor) / 100);
if (newCapacity == currentCapacity ) {
newCapacity++;
}
Object[] newStore = new Object[ newCapacity ];
System.arraycopy( this.storedObjects, 0, newStore, 0, this.size );
this.storedObjects = newStore;
}
public Object[] getInternalArray() {
return this.storedObjects;
}
}
[/code]
