Java List Move Item moveUp(List list, int[] selectionIndexes)

Description

Move the selected items up one position in the list.

License

Open Source License

Parameter

Parameter	Description
list	The list of items, which will be altered in-place.
selectionIndexes	The indexes of the items to be moved.

Return

Whether any items have been moved. For example, would return false if the selected items were already at the top of the list.

Declaration

public static <T> boolean moveUp(List<T> list, int[] selectionIndexes) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright (c) 2010 Neil Bartlett./*from  ww  w .j  a v  a2  s.c  o m*/
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Neil Bartlett - initial API and implementation
 *******************************************************************************/

import java.util.List;

public class Main {
    /**
     * Move the selected items up one position in the list.
     * 
     * @param list
     *            The list of items, which will be altered in-place.
     * @param selectionIndexes
     *            The indexes of the items to be moved.
     * @return Whether any items have been moved. For example, would return false if the selected items were already at
     *         the top of the list.
     */
    public static <T> boolean moveUp(List<T> list, int[] selectionIndexes) {
        boolean moved = false;

        int size = list.size();
        for (int i = size - 1; i >= 0; i--) {
            T item = list.get(i);
            if (arrayContains(selectionIndexes, i)) {
                // Find next unselected item
                int nextUnselected = -1;
                int j = i - 1;
                while (j >= 0) {
                    if (!arrayContains(selectionIndexes, j)) {
                        nextUnselected = j;
                        break;
                    }
                    j--;
                }
                // Swap with it
                if (nextUnselected != -1) {
                    list.set(i, list.get(nextUnselected));
                    list.set(nextUnselected, item);
                    moved = true;
                }
            }
        }
        return moved;
    }

    private static boolean arrayContains(int[] array, int item) {
        for (int i : array) {
            if (i == item)
                return true;
        }
        return false;
    }
}

Related

1. moveRows(final List allRows, final List rowsToMove, final int index)
2. moveToFront(List aList, Object anObj)
3. moveTop(List list, int[] indices)
4. moveUp(final List list, final T toMoveUp)
5. moveUp(List