initial commit of BRouter Version 0.98

brouter-util/src/main/java/btools/util/LazyArrayOfLists.java

@@ -0,0 +1,53 @@
+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();
+      }
+    }
+  }
+}