53 lines
1,008 B
Java
53 lines
1,008 B
Java
package btools.util;
|
|
|
|
import java.util.List;
|
|
import java.util.ArrayList;
|
|
|
|
/**
|
|
* Behaves like an Array of list
|
|
* with lazy list-allocation at getList
|
|
*
|
|
* @author ab
|
|
*/
|
|
public class LazyArrayOfLists<E>
|
|
{
|
|
private ArrayList<ArrayList<E>> lists;
|
|
|
|
public LazyArrayOfLists( int size )
|
|
{
|
|
lists = new ArrayList<ArrayList<E>>( size );
|
|
for ( int i = 0; i< size; i++ )
|
|
{
|
|
lists.add( null );
|
|
}
|
|
}
|
|
|
|
public List<E> getList( int idx )
|
|
{
|
|
ArrayList<E> list = lists.get( idx );
|
|
if ( list == null )
|
|
{
|
|
list = new ArrayList<E>();
|
|
lists.set( idx, list );
|
|
}
|
|
return list;
|
|
}
|
|
|
|
public int getSize( int idx )
|
|
{
|
|
List<E> list = lists.get( idx );
|
|
return list == null ? 0 : list.size();
|
|
}
|
|
|
|
public void trimAll()
|
|
{
|
|
for ( int idx = 0; idx< lists.size(); idx++ )
|
|
{
|
|
ArrayList<E> list = lists.get( idx );
|
|
if ( list != null )
|
|
{
|
|
list.trimToSize();
|
|
}
|
|
}
|
|
}
|
|
}
|