Previous element in array list
hello ppl..
i hope u guys can help me here.. i am developing a program that sort an amount of strings and output to a file..and i place them inside an array list..i use Collections.sort to sort it..
now the problem is..i want to handle duplicate strings meaning deleting the duplicate strings..however my code doesnt seem to work..here it is
Iterator check = c.iterator();
while (check.hasNext() == true)
if (check.previous() == check.next())
check.remove();
br.write(check.next() + "\r\n");
c is my arraylist name. JDK's error is they cannot resolve symbol previous () method but i found it inside util and i imported the whole util..by import java.util.*;
Please help..thank you
Good catch. It's very rare that you use == to compare objects. You only do that when you want to see if the two references are both aimed at the same object. Normally what you want to do (and what should be done here) is to use equals to see if the two objects' "contents" or "values" are the same.
>
if (check.previous() == check.next())Did you use this piece in the program?
If so could this be the problem?
I think that when you use the "==" operator it checks
to see if the two objects share the same memory
location.
Like when you are comparing Strings you must use the
String.equals(String s) method they they will never
match with "==".
Maybe this is not the problem but I like to
ramble...
-- Ian
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Edited by: drakester on Oct 10, 2007 11:53 AMdrakester wrote:
This is the code I have and it's not updating the previous element in the list with "D" and I have no idea why?That code looks correct enough. There are a couple things you're doing which are unnecessary: You don't need to check for a null previousAccountNumber - assuming accountNumber isn't null (which it isn't or you'd have another problem), a non-null string is never equal to a null one. And there's no need to check for iter.hasPrevious nor hasNext, because if you have found a duplicate, obviously there is a previous item, it's the duplicate one you already saw. So you move to that item and mark it. Then obviously there's a next item too, because you just moved back one item and need to move forward again to the current item you were just working on.
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Using VARRAYs as parameters to a Stored Procedure
showing an example on how to get the conection to create the varray, as well as
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Hi, all:
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try {
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rowScanner.useDelimiter(",\\s*");//that scanner can use whitespace or commas as the delimiter between information.
while (rowScanner.hasNext()) {//while there's still information in that scanner,
String piece = rowScanner.next(); //gets each piece of information from the row scanner.
double x = Double.valueOf(piece);//casts that stringed piece to a double.
checker.add(x);//adds those doubles to the array list checker.
catch (NoSuchElementException nsee) {
nsee.printStackTrace();
//System.out.println("checker contains: " + checker);
processARowIntoArrayLists(checker);//sends checker to the method that splits it up into its columns.
} -
Accessing Array and Iterating Array list - Need Oracle Pro Assistance
Hi,
This is the third time i am posting the question, :( .
I want some advice on how to iterate through a Array list which has an array of tasks/processes and make calls to the corresponding subprocess for each element in the list.
We are looking for a BPMN approach.
Any example or ideas would be of great help.
My requirement states that i will get a list of tasks from a Rules Engine and i have to use BPM to iterate through the tasks and make calls to each tasks(which is a subprocess call).
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I am using BPM Oracle 11g but any help 10 will also help us.
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Thanks
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With a list of Instances, you can search for that instance and notify it...
If you have a list of processes, that need to be started, you can create an instance within that process....
user9083699 wrote:
My requirement states that i will get a list of tasks from a Rules Engine and i have to use BPM to iterate through the tasks and make calls to each tasks(which is a subprocess call).If you are just trying to initiate a sub-process, (btw, why would they have to be subprocesses?), It sounds like you should be able to create a global in the process, and just call it with PAPI...
I'm still a little fuzzy, on how this business requirement turned up... however, maybe this helps a little?
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Accessing Array and Iterating Array list
Hi,
I want some advice on how to iterate through a Array list which has an array of tasks/processes and make calls to the corresponding subprocess for each element in the list using BPM 11g
We are looking for a BPMN approach.
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I am reposting again this question , hoping that someone will help us
ThanksOthers probably are getting it, but I'm not really sure what it is that you're tyring to do with the list of instances.
I'm getting lost in two areas. First, you mentioned you have a rules engine returning a list of instances. Mostly out of curiosity - why do you have an array of instances being created by a rules engine? What is the use case? Asking because I'm sure to learn something new from you on this - I'm used to seeing a lot of things coming back from an invoked rule, but never an array of instances before.
Second (sure you know this), in both 10g and 11g there is a Split-N activity that you can use to parse (as the name implies) "N" number of instances. This "N" is discoverable at runtime. If you have 14 instances in your array at runtime, it would go into a Split-N activity and 14 instances would automatically be spawned. The 14 instances would flow from the Split-N to its corresponding Join activity in the process.
Dan -
How can i check to see if an object is already in the array list?
while (res.next()) {
Schedule schedule = new Schedule();
customerName = res.getString("CUSTOMERNAME");
schedule.setCustomerName(customerName);
magName = res.getString("MAGNAME");
schedule.setMagName(magName);
System.out.println("NAME: " + customerName);
System.out.println("MAGNAME: " + magName);
if(!scheduleListH.contains(schedule)) //this won't work
scheduleListH.add(schedule);
}schedule object has 2 fields, customerName and MagName;
Basically i want to say, IF the scheudleList (which is an array list) contains an object schedule that has the same customerName and MagName as any of the objects in the array list, don't readd the object.
ANy help would be great!Thanks!
Oops I forogt I could use the .contains, i also tried that but still no luck.
There is no compiler error but here is an example of the output:
Populating scheudle list for HOLIDAY selection data structure:
NAME: Cory
MAGNAME: Merlin
NAME: Brandon
MAGNAME: Gondorf
NAME: Chris
MAGNAME: Houdini
NAME: Lokie
MAGNAME: Blaine
Sample SCHEDUEL H [Cory Merlin, Brandon Gondorf, Chris Houdini, Lokie Blaine]As you can see, There are 4 objects in the array list:
Cory Merlin
Brandon Gondorf
Chris Houdini
Lokie BLaine
Now this function is called everytime the user choses a new item in a combo box.
So if they go back to the previous selection, Holiday's, it shouldn't read add all the orginal things.
But if I go up and select the same item in the combo box it changes whats in the array list to the following:
Populating scheudle list for HOLIDAY selection data structure:
NAME: Cory
MAGNAME: Merlin
NAME: Brandon
MAGNAME: Gondorf
NAME: Chris
MAGNAME: Houdini
NAME: Lokie
MAGNAME: Blaine
Sample SCHEDUEL H [Cory Merlin, Brandon Gondorf, Chris Houdini, Lokie Blaine, Cory Merlin, Brandon Gondorf, Chris Houdini, Lokie Blaine]Here's my whole function if your interested and where I call it:
void populateSchedule(String holiday) {
Statement sta = null;
Connection connection6 = null;
try {
connection6 = DriverManager.getConnection(URL, USERNAME, PASSWORD);
sta = connection6.createStatement();
//getting the list of magicians from the selected holiday to see if any are free
ResultSet res = sta.executeQuery(
"SELECT CUSTOMERNAME, MAGNAME FROM SCHEDULE WHERE HOLIDAYNAME = '" + holiday + "'");
String customerName = " ";
String magName = " ";
System.out.println("Populating scheudle list for HOLIDAY selection data structure: ");
//this is where I add the waiting list objects to the array that will later be used
//to print out and shown to the user when they select the waiting list status
while (res.next()) {
Schedule schedule = new Schedule();
customerName = res.getString("CUSTOMERNAME");
schedule.setCustomerName(customerName);
magName = res.getString("MAGNAME");
schedule.setMagName(magName);
System.out.println("NAME: " + customerName);
System.out.println("MAGNAME: " + magName);
if(!scheduleListH.contains(schedule))
scheduleListH.add(schedule);
System.out.println("Sample SCHEDUEL H " + scheduleListH);
} catch (SQLException ex) {
System.out.println(ex);
ex.printStackTrace();
} finally {
try {
sta.close();
connection6.close();
} catch (SQLException ex) {
Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
//this is where i call in the GUI
private void specStatusComboBoxActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String selectedItem = (String)specStatusComboBox.getSelectedItem();
String groupSelectedItem = (String) groupStatusComboBox.getSelectedItem();
if(groupSelectedItem.equals("Holidays"))
//get customer name and magician name from the Scheduel table
//use selectedItem (it will be a holiday name)
//magicDB.clearScheduleHList();
magicDB.populateSchedule(selectedItem);
ArrayList<Schedule> tempScheduleList = magicDB.getScheduleHListCopy();
outputTextArea.setText(" ");
outputTextArea.setText("CUSTOMER NAME" +"\t\t" + "MAGICIAN NAME" + "\n");
for(int i = 0; i < tempScheduleList.size(); i++)
outputTextArea.append(tempScheduleList.get(i).toString() + "\n");
} I'll reward the duke stars anyways because you have been a great help either way! -
A suggestion : use "loop array list" instead of ArrayList / LinkedList
ArrayList is good at:
get / set by index : O(1)
appending : O(log(n))
remove last : O(1)
and very bad at:
add middle : O(n)
remove from middle : O(n)
LinkedList is good at:
fast remove from middle, if your iteraror already goes there : O(1)
convenient methods : addFirst, addLast, removeFirst, removeLast : O(1)
and very bad at :
get / set by index : O(n)
here I want to make a suggestion : use "loop array list" instead of the ArrayList and LinkedList.
a "loop array list" is based on array, just like ArrayList. But it has 2 member-variables : the start position, and the real size. the start position can be anywhere within array.length. an element of index "i" is stored in array[ start + i ], and when (start + i > array.length), loop to the beginning of the array; when (start + i < 0), loop to the end of the array.
this "loop array list" has all the good sides:
get / set by index : O(1)
add first / last : O(log(n))
remove first / last : O(log(n))
add / remove from middle : O(n)
(note : because we shrink the backup-array when the real size is too small, add / remove operation take O(log(n)) now.)
the only problem is : add / remove from middle. let's take a look at it.
1. the LinkedList does NOT really add/remove from middle in O(1), you has to locate the element, which is O(n).
2. O(n) is acceptable, O(n^2) is not acceptable. try this : keep removing first element from an very big ArrayList ( size>10^6 ) until it's empty.
the fact is, any list can perform batch-remove / batch-add operation in O(n) instead of O(n^2). it's easy : allocate a new list, iterate the original list, copy the element into the new list if condition is satisfied.
so, instead of "remove from middle", what we need is a new methods : removeAllByCondition( Condition condition ), and now the batch-remove operation can be done in O(n)
here is an implementation of mine. I've tested it on my computer( 512mem + 2G cpu, win2k + jdk1.5 ), it's amazing, just a little slower then ArrayList when add last, and a liitle slower then LinkedList when batch-remove. in all other cases, it's far more better then those 2 kinds of List.
// source code : List2
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
public final class List2<T> extends AbstractList<T> {
private static int initialArrayLength = 4;
private T[] array;
private int start;
private int size;
private void init( T[] newArray, int start_a, int size_a ) {
array = newArray;
start = start_a;
size = size_a;
@SuppressWarnings("unchecked")
private void init() {
init( (T[]) new Object[ initialArrayLength ], 0, 0 );
public List2() {
init();
@SuppressWarnings("unchecked")
public List2( Collection<? extends T> collection ) {
init(
collection.toArray( (T[]) new Object[ collection.size() * 11 / 10 + 1 ] ),
0,
collection.size()
private List2( T[] array_a, int start_a, int size_a ) {
init( array_a, start_a, size_a );
@SuppressWarnings("unchecked")
public static <TT> List2<TT> createV( TT... elements ) {
TT[] array = (TT[]) new Object[ elements.length * 11 / 10 + 1 ];
System.arraycopy( elements, 0, array, 0, elements.length );
return new List2<TT>( array, 0, elements.length );
public static List2<Double> create( double... elements ) {
Double[] array = new Double[ elements.length * 11 / 10 + 1 ];
for( int i=0; i < elements.length; i++ )
array[i] = elements;
return new List2<Double>( array, 0, elements.length );
public static List2<Integer> create( int... elements ) {
Integer[] array2 = new Integer[ elements.length * 11 / 10 + 1 ];
for( int i=0; i < elements.length; i++ )
array2[i] = elements[i];
return new List2<Integer>( array2, 0, elements.length );
public static List2<Character> create( char... elements ) {
Character[] array2 = new Character[ elements.length * 11 / 10 + 1 ];
for( int i=0; i < elements.length; i++ )
array2[i] = elements[i];
return new List2<Character>( array2, 0, elements.length );
public static List2<Character> create( String s ) {
return create( s.toCharArray() );
public List2<T> clone() {
return new List2<T>( this );
// basic
public int size() {
return size;
private int index( int index ) {
int i = start + index;
if( i >= array.length )
i -= array.length;
return i;
public T get( int d ) {
if( d < 0 || d >= size )
throw new IndexOutOfBoundsException();
if( size == 0 )
throw new NoSuchElementException();
return array[ index( d ) ];
public T set( int index, T element ) {
if( index < 0 || index >= size )
throw new IndexOutOfBoundsException();
int i = index( index );
T oldElement = array[i];
array[i] = element;
return oldElement;
@SuppressWarnings("unchecked")
private void copyAndSetToNewArray( int newArrayLength ) {
T[] newArray = (T[]) new Object[ newArrayLength ];
for( int i=0; i<size; i++ )
newArray[i] = array[ index( i ) ];
init( newArray, 0, size );
public void addFirst( T element ) {
if( size == array.length )
copyAndSetToNewArray( size * 3 / 2 + 1 );
int i = index( array.length - 1 );
array[ i ] = element;
start = i;
size++;
public void addLast( T element ) {
if( size == array.length )
copyAndSetToNewArray( size * 3 / 2 + 1 );
array[ index( size ) ] = element;
size++;
public T removeFirst() {
if( size == 0 )
throw new NoSuchElementException();
T oldElement = array[ start ];
array[ start ] = null;
start = index( 1 );
size--;
if( array.length > size * 2 + 1 )
copyAndSetToNewArray( size * 11 / 10 + 1 );
return oldElement;
public T removeLast() {
if( size == 0 )
throw new NoSuchElementException();
int i = index( size - 1 );
T oldElement = array[i];
array[i] = null;
size--;
if( array.length > size * 2 + 1 )
copyAndSetToNewArray( size * 11 / 10 + 1 );
return oldElement;
@SuppressWarnings("unchecked")
public int removeAll( ListCondition<T> condition ) {
T[] newArray = (T[]) new Object[ array.length ];
int iNew = 0;
for( int i=0; i < size; i++ ) {
T element = get( i );
if( ! condition.isConditionSatisfied( this, i, element ) )
newArray[ iNew++ ] = element;
int oldSize = size;
init( newArray, 0, iNew );
if( array.length > size * 2 + 1 )
copyAndSetToNewArray( size * 11 / 10 + 1 );
return size - oldSize;
// aux
public boolean equals(Object obj) {
if( obj == this )
return true;
if( obj instanceof List2 ) {
List2 that = (List2) obj;
if( this.size != that.size )
return false;
for( int i=0; i < size; i++ )
if( ! Tools.equals( this.array[ this.index(i) ], that.array[ that.index(i) ] ) )
return false;
return true;
if( obj instanceof List ) {
List that = (List) obj;
if( this.size != that.size() )
return false;
Iterator thatIter = that.iterator();
for( int i=0; i < size; i++ )
if( ! Tools.equals( this.array[ this.index(i) ], thatIter.next() ) )
return false;
return true;
return true;
public int hashCode() {
int hashCode = 1;
for( int i=0; i < size; i++ ) {
T element = array[ index( i ) ];
hashCode = 31*hashCode + ( element==null ? 0 : element.hashCode() );
return hashCode;
public boolean isEmpty() {
return size == 0;
public T getFirst() {
return get( 0 );
public T getLast() {
return get( size() - 1 );
public T getRandom() {
return get( (int) (Math.random() * size) );
public int indexOf( Object element ) {
for( int i=0; i < size; i++ )
if( Tools.equals( array[ index( i ) ], element ) )
return i;
return -1;
public int lastIndexOf( Object element ) {
for( int i=size-1; i >= 0; i-- )
if( Tools.equals( array[ index( i ) ], element ) )
return i;
return -1;
public boolean contains( Object element ) {
return indexOf( element ) != -1;
public boolean add( T element ) {
addLast( element );
return true;
@Deprecated
public void add( int index, T element ) {
throw new UnsupportedOperationException();
public T remove() {
return removeFirst();
@Deprecated
public boolean remove( Object element ) {
throw new UnsupportedOperationException( "use removeAll( Condition ) instead" );
@Deprecated
public T remove( int index ) {
throw new UnsupportedOperationException( "use removeAll( Condition ) instead" );
public void clear() {
init();
public Object[] toArray() {
Object[] result = new Object[ size ];
for( int i=0; i < size; i++ )
result[i] = array[ index( i ) ];
return result;
@SuppressWarnings("unchecked")
public <TT> TT[] toArray( TT[] a ) {
if( a.length < size )
a = (TT[]) java.lang.reflect.Array.newInstance( a.getClass().getComponentType(), size );
for( int i=0; i < size; i++ )
a[i] = (TT) array[ index( i ) ];
if( a.length > size )
a[size] = null;
return a;
@SuppressWarnings("unchecked")
public void sort() {
Object[] a = toArray();
Arrays.sort( a );
for( int i=0; i < size; i++ )
array[ i ] = (T) a[ i ];
start = 0;
@SuppressWarnings("unchecked")
public void sortDesc() {
Object[] a = toArray();
Arrays.sort( a );
for( int i=0, j=size-1; i < size; i++, j-- )
array[ i ] = (T) a[ j ];
start = 0;
@SuppressWarnings("unchecked")
public void sort( Comparator<T> comparator ) {
T[] a = (T[]) toArray();
Arrays.sort( a, comparator );
for( int i=0; i < size; i++ )
array[ i ] = a[ i ];
start = 0;
@SuppressWarnings("unchecked")
public void sortDesc( Comparator<T> comparator ) {
T[] a = (T[]) toArray();
Arrays.sort( a, comparator );
for( int i=0, j=size-1; i < size; i++, j-- )
array[ i ] = a[ j ];
start = 0;
public String toString( String delimiter ) {
return toString( "", delimiter, "", size() );
public String toString( String prefix, String delimiter, String suffix, int max ) {
StringBuffer stringBuffer = new StringBuffer( prefix );
int dest = Math.min( max, size );
for( int i=0; i < dest; i++ ) {
stringBuffer.append( get(i) );
if( i < dest - 1 )
stringBuffer.append( delimiter );
if( size > max )
stringBuffer.append( "...(" ).append( size() - max ).append( " more)" );
stringBuffer.append( suffix );
return stringBuffer.toString();
// batch operation
public boolean containsAll( Collection<?> that ) {
Set<Object> thisSet = new HashSet<Object>( this );
for( Object element : that )
if( ! thisSet.contains( element ) )
return false;
return true;
@SuppressWarnings("unchecked")
public List2<T> subList( int fromIndex, int toIndex ) {
if( fromIndex < 0 || toIndex > size || toIndex < fromIndex )
throw new IndexOutOfBoundsException();
int newSize = toIndex - fromIndex;
T[] newArray = (T[]) new Object[ newSize * 11 / 10 + 1 ];
for( int i=fromIndex, iNew=0; i < toIndex; i++, iNew++ )
newArray[ iNew ] = array[ index( i ) ];
return new List2<T>( newArray, 0, newSize );
public void addV( T... that ) {
for( T element : that )
addLast( element );
public boolean addAll( Collection<? extends T> that ) {
for( T element : that )
addLast( element );
return ! that.isEmpty();
@Deprecated
public boolean addAll( int index, Collection<? extends T> c ) {
throw new UnsupportedOperationException();
public void removeRest( T element ) {
int position = lastIndexOf( element );
if( position == -1 )
return;
while( ! Tools.equals( element, removeLast() ) );
public void removeAllEquals( final T element ) {
removeAll( new ListCondition<T>() { public boolean isConditionSatisfied(List2 list, int index, T currentElement) {
return currentElement.equals( element );
public void removeAllBetween( final T from, final T to ) {
removeAll( new ListCondition<T>() {
@SuppressWarnings("unchecked")
public boolean isConditionSatisfied(List2 list, int index, T element) {
if( from != null && ((Comparable) from).compareTo( element ) > 0 )
return false;
if( to != null && ((Comparable) to).compareTo( element ) <= 0 )
return false;
return true;
public boolean retainAll( Collection<?> that ) {
final Set<Object> thatSet = new HashSet<Object>( that );
int removeCount = removeAll( new ListCondition<T>() { public boolean isConditionSatisfied(List2 list, int index, T element) {
return ! thatSet.contains( element );
return removeCount > 0;
public boolean removeAll( Collection<?> that ) {
final Set<Object> thatSet = new HashSet<Object>( that );
int removeCount = removeAll( new ListCondition<T>() { public boolean isConditionSatisfied(List2 list, int index, T element) {
return thatSet.contains( element );
return removeCount > 0;
// unit test
private static int maxTestCount = 1000 * 1000;
public static void unitTest() throws Exception {
// thest thoese methods for one time
Tools.ensureEquals( new List2(), new ArrayList() );
Tools.ensureNotEquals( List2.create( "abcde" ), new ArrayList() );
Tools.ensureNotEquals( List2.create( "abcde" ), List2.create( "abcdef" ) );
final List<Double> list1 = new ArrayList<Double>();
final List2<Double> list2 = new List2<Double>();
Runnable[] tasks = new Runnable[] {
// test those methods that do NOT change the list
new Runnable() { public void run() {
Tools.ensureEquals( new List2<Double>( list1 ), list1 );
Tools.ensureEquals( List2.createV( list1.toArray() ), list1 );
Tools.ensureEquals( List2.createV( list1.toArray( new Double[0] ) ), list1 );
double[] doubles = new double[ list1.size() ];
int i = 0;
for( double d : list1 )
doubles[i++] = d;
Tools.ensureEquals( List2.create( doubles ), list1 );
Tools.ensure( list1.isEmpty() == list2.isEmpty() );
Arrays.equals( list1.toArray(), list2.toArray() );
Tools.ensureEquals( list1, list2.clone() );
Double notExistElement = -2.0;
Tools.ensure( list1.indexOf( notExistElement ) == -1 );
Tools.ensure( list1.lastIndexOf( notExistElement ) == -1 );
Tools.ensure( list1.contains( notExistElement ) == false );
Tools.ensureEquals( list1.toString(), list2.toString() );
Tools.ensureEquals( list1.toString(), list2.toString() );
Tools.ensureEquals( list1.hashCode(), list2.hashCode() );
if( list1.isEmpty() )
return;
Tools.ensure( list1.get(0).equals( list2.getFirst() ) );
Tools.ensure( list1.get(list1.size()-1).equals( list2.getLast() ) );
Double existRandomElement = list2.getRandom();
Tools.ensure( list1.contains( existRandomElement ) );
Tools.ensure( list2.contains( existRandomElement ) );
Tools.ensure( list1.indexOf( existRandomElement ) == list2.indexOf( existRandomElement ) );
Tools.ensure( list1.indexOf( existRandomElement ) == list2.indexOf( existRandomElement ) );
int from = (int) (Math.random() * list1.size());
int to = (int) (Math.random() * (list1.size()+1));
if( from > to ) {
int t = from;
from = to;
to = t;
Tools.ensureEquals( list1.subList( from, to ), list2.subList( from, to ) );
// test those methods that change the list
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
int i = (int) (Math.random() * list1.size());
double d = Math.random();
list1.set( i, d );
list2.set( i, d );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
int i = (int) (Math.random() * list1.size());
Tools.ensure( list1.get( i ).equals( list2.get( i ) ) );
new Runnable() { public void run() {
double d = Math.random();
list1.add( 0, d );
list2.addFirst( d );
new Runnable() { public void run() {
double d = Math.random();
list1.add( d );
list2.addLast( d );
new Runnable() { public void run() {
double d = Math.random();
list1.add( d );
list2.addLast( d );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
Tools.ensure( list1.remove( 0 ).equals( list2.removeFirst() ) );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
Tools.ensure( list1.remove( list1.size() - 1 ).equals( list2.removeLast() ) );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
int i = 0;
for( Iterator<Double> iter=list1.iterator(); iter.hasNext(); i++ ) {
iter.next();
if( i % 3 == 0 )
iter.remove();
list2.removeAll( new ListCondition<Double>() { public boolean isConditionSatisfied(List2 list, int index, Double element) {
return index % 3 == 0;
new Runnable() { public void run() {
double d = Math.random();
list1.add( d );
list2.add( d );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
Tools.ensure( list1.remove(0).equals( list2.remove() ) );
new Runnable() { public void run() {
if( list1.isEmpty() )
return;
int r = (int) (Math.random() * list1.size());
Double element = list1.get( r );
int index = list1.lastIndexOf( element );
for( int i=list1.size()-1; i>=index; i-- )
list1.remove( i );
list2.removeRest( element );
new Runnable() { public void run() {
list2.removeRest( Math.random() - 2 );
new Runnable() { public void run() {
list1.clear();
list2.clear();
new Runnable() { public void run() {
Collections.sort( list1 );
list2.sort();
new Runnable() { public void run() {
Collections.sort( list1 );
Collections.reverse( list1 );
list2.sortDesc();
new Runnable() { public void run() {
Comparator<Double> comparator = new Comparator<Double>() { public int compare(Double o1, Double o2) {
return o1.toString().substring(2).compareTo( o2.toString().substring(2) );
Collections.sort( list1, comparator );
list2.sort( comparator );
new Runnable() { public void run() {
Comparator<Double> comparator = new Comparator<Double>() { public int compare(Double o1, Double o2) {
return o1.toString().substring(2).compareTo( o2.toString().substring(2) );
Collections.sort( list1, comparator );
Collections.reverse( list1 );
list2.sortDesc( comparator );
new Runnable() { public void run() {
Double notExistElement = -2.0;
list2.removeAllEquals( notExistElement );
Tools.ensureEquals( list1, list2 );
list2.removeAllBetween( 0.5, 0.6 );
for( Iterator<Double> iter=list1.iterator(); iter.hasNext(); ) {
double d = iter.next();
if( d >= 0.5 && d < 0.6 )
iter.remove();
Tools.ensureEquals( list1, list2 );
System.out.print( "test List2 " );
for( int i=0; i < maxTestCount; i++ ) {
tasks[ (int) (Math.random() * tasks.length) ].run();
Tools.ensureEquals( list1, list2 );
if( i % (maxTestCount/10) == 0 )
System.out.print( "." );
System.out.println( " ok" );
// source code : ListCondition
public interface ListCondition<T> {
boolean isConditionSatisfied( List2 list, int index, T element );Hi,
I have the following statement:
private List list = new ArrayList();
why not use private ArrayList list = new
ArrayList()?
I know ArrayList implements List, so list has a wide
scope, right? What's the benefit?
Thanks,
JieBy using the interface you are not tied to a specific implementation.
Later, you may determine that using a LinkedList is more efficient to your specific code and then all you need to do is change the statement to:
private List list = new LinkedList();As long as you are not casting the list reference to ArrayList (or something along those lines) you would not need to change anything else. -
Sort array list and using comparable
With the following code I would like to setup a score object for the current player.
Change it to a string(Is it correct to say parse it to a string type)
Then add it to the arraylist.
So I can sort the array list according to the string size.
That's why I have the variables in that order.
So if 3 players have the same amount of guesses, they can be positioned on the high score list according to their gameTime.
//create score object
Score currentScore = new Score(guessCount, gameTime, name);
String currentScoreToString = currentScore.toString();
//add score to arrayList
scores.add(currentScoreToString);So the error message says " The method add(Score) in the type arrayList <Score> is not applicable for the arguments(string)"
Now, I understand that, I would like to know if there is another way to achieve what I am trying to do.
Is the string idea I am trying here possible? is it practical or should I use comparable?
I have looked at comparable, but I don't get it.
Will my Score class implement comparable. I am looking at an example with the following code.
Employee.java
public class Employee implements Comparable {
int EmpID;
String Ename;
double Sal;
static int i;
public Employee() {
EmpID = i++;
Ename = "dont know";
Sal = 0.0;
public Employee(String ename, double sal) {
EmpID = i++;
Ename = ename;
Sal = sal;
public String toString() {
return "EmpID " + EmpID + "\n" + "Ename " + Ename + "\n" + "Sal" + Sal;
public int compareTo(Object o1) {
if (this.Sal == ((Employee) o1).Sal)
return 0;
else if ((this.Sal) > ((Employee) o1).Sal)
return 1;
else
return -1;
ComparableDemo.java
import java.util.*;
public class ComparableDemo{
public static void main(String[] args) {
List ts1 = new ArrayList();
ts1.add(new Employee ("Tom",40000.00));
ts1.add(new Employee ("Harry",20000.00));
ts1.add(new Employee ("Maggie",50000.00));
ts1.add(new Employee ("Chris",70000.00));
Collections.sort(ts1);
Iterator itr = ts1.iterator();
while(itr.hasNext()){
Object element = itr.next();
System.out.println(element + "\n");
}The thing I don't understand is why it returns 0, 1 or -1(does it have to do with the positioning according to the object is being compared with?)
What if I only use currentScore in a loop which loops every time the player restarts?
//create score object
Score currentScore = new Score(guessCount, gameTime, name);
String currentScoreToString = currentScore.toString();
//add score to arrayList
scores.add(currentScoreToString);Also why there is a method compareTo, and where is it used?
Thanks in advance.
Edited by: Implode on Oct 7, 2009 9:27 AM
Edited by: Implode on Oct 7, 2009 9:28 AMjverd wrote:
Implode wrote:
I have to hand in an assignment by Friday, and all I have to do still is write a method to sort the array list. Okay, if you have to write your own sort method, then the links I provided may not be that useful. They show you how to use the sort methods provided by the core API. You COULD still implement Comparable or Comparator. It would just be your sort routine calling it rather than the built-in ones.
You have two main tasks: 1) Write a method that determines which of a pair of items is "less than" the other, and 2) Figure out a procedure for sorting a list of items.
The basic idea is this: When you sort, you compare pairs of items, and swap them if they're out of order. The two main parts of sorting are: 1) The rules for determining which item is "less than" another and 2) Determining which pairs of items to compare. When you implement Comparable or create a Comparator, you're doing #1--defining the rules for what makes one object of your class "less than" another. Collections.sort() and other methods in the core API will call your compare() or compareTo() method on pairs of objects to produce a sorted list.
For instance, if you have a PersonName class that consists of firstName and lastName, then your rules might be, "Compare last names. If they're different, then whichever lastName is less indicates which PersonName object is less. If they're the same, then compare firstNames." This is exactly what we do in many real-life situations. And of course the "compare lastName" and "compare firstName" steps have their own rules, which are implemented by String's compareTo method, and which basically say, "compare char by char until there's a difference or one string runs out of chars."
Completely independent of the rules for comparing two items is the algorithm for which items get compared and possibly swapped. So, if you have 10 Whatsits (W1 through W10) in a row, and you're asked to sort them, you might do something like this:
Compare the current W1 to each of W2 through W10 (call the current one being compared Wn). If any of them are less than W1, swap that Wn with W1 and continue on, comparing the new W1 to W(n+1) (that is, swap them, and then compare the new first item to the next one after where you just swapped.)
Once we reach the end of the list, the item in position 1 is the "smallest".
Now repeat the process, comparing W2 to W3 through W10, then W3 to W4 through W10, etc. After N steps, the first N positions have the correct Whatsit.
Do you see how the comparison rules are totally independent of the algorithm we use to determine which items to compare? You can define one set of comparison rules ("which item is less?") for Whatsits, another for Strings, another for Integers, and use the same sorting algorithm on any of those types of items, as long as you use the appropriate comparison rules.Thanks ;)
massive help
I understand that now, but I am clueless on how to implement it.
Edited by: Implode on Oct 7, 2009 10:56 AM -
Accessing Array and Iterating Array list - call corresponding subprocess
Hi,
I want some advice on how to iterate through a Array list which has an array of tasks/processes and make calls to the corresponding subprocess for each element in the list.
Any example or ideas would be of great help.
My requirement states that i will get a list of tasks from a Rules Engine and i have to use BPM to iterate through the tasks and make calls to each tasks(which is a subprocess call).
ThanksAre you using Oracle BPM 10 or are you using 11?
Dan -
How to get a value from the previous element (XSLT/XPATH gurus ahoy!)
Hi All,
I am building an RTF template for a "letter of reference"-report. Sometimes there are several rows in the data, that need to be printed as one. This is due to consecutive temporary contracts, which will be printed out as one period of service.
Here's a simplified data example to illustrate the problem.
<ROW>
<START_DATE>01-01-1980</START_DATE>
<END_DATE>01-01-1988</END_DATE>
</ROW>
<ROW>
<START_DATE>01-01-1988</START_DATE>
<END_DATE>01-01-1990</END_DATE>
</ROW>
<ROW>
<START_DATE>01-01-2000</START_DATE>
<END_DATE>01-01-2005</END_DATE>
</ROW>
With the data above, I should print two lines:
01-01-1980 - 01-01-1990
01-01-2000 - 01-01-2005
I need to compare START_DATE of an element (except for the first one) with the END_DATE of the previous element, to find out whether to print the END_DATE for that element or not. How can I get that value from the previous element?
Thanks & Regards, Matildause this to get the following End_date
<?following-sibling::../END_DATE?>
Try this
<?for-each:/ROOT/ROW?>
==================
Current StartDate <?START_DATE?>
Current End Date <?END_DATE?>
Next Start Date <?following-sibling::ROW/END_DATE?>
Previous End Date <?preceding-sibling::ROW[1]/END_DATE?>
================
<?end for-each?>
o/p
==================
Current StartDate 01-01-1980
Current End Date 01-01-1988
Next Start Date 01-01-1990
Previous End Date
================
==================
Current StartDate 01-01-1988
Current End Date 01-01-1990
Next Start Date 01-01-2005
Previous End Date 01-01-1988
================
==================
Current StartDate 01-01-2000
Current End Date 01-01-2005
Next Start Date
Previous End Date 01 -
I have just re-installed itunes. The previous user is still listed. When I try to login in with my account, Apple says to view my account.
When I do that, it reverts back to the other user. I want the other user totally off of my system. How do I do this?Try Store > Sign Out followed by Store > Sign In...
tt2 -
Adding two array lists together and a text file to an array list
I'm having problems coding these two methods... Could someone explain how to do this? I can't find information on it anywhere... :(
"MagazineList" is the class I'm coding in right now, and I already declared "list" as an array list of another class called "Magazine".
public boolean addAll(MagazineList magazines)
if (list == magazines) {
return false;
else {
list.addAll(magazines);
return true;
public boolean addAll(String filename)
Scanner in = ResourceUtil.openFileScanner(filename);
if (in == null) {
return false;
String line = source.nextLine();
while (!line.equals("")) {
list.add(Magazine(source));
in.close();
}I assume "addAll(MagazineList magazines)" is defined in the MagazineList class?
Then,
list.addAll(magazines);probably needs to be something like:
list.addAll(magazines.list);This uses the private variable ( should be private) list from the input MagazineList, and adds all of those Magazine objects to the list in the current MagazineList.
But, yes, describe your problems more clearly, and you'll get better answers more quickly (because people will be able to understand you and give you a suggestion without asking you another question first).
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