| /* ==================================================================== |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You under the Apache License, Version 2.0 |
| (the "License"); you may not use this file except in compliance with |
| the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| ==================================================================== */ |
| |
| package org.apache.poi.util; |
| |
| |
| import java.util.Arrays; |
| |
| /** |
| * Utility classes for dealing with arrays. |
| */ |
| @Internal |
| public final class ArrayUtil { |
| |
| private ArrayUtil() {} |
| |
| /** |
| * Moves a number of entries in an array to another point in the array, |
| * shifting those inbetween as required. |
| * @param array The array to alter |
| * @param moveFrom The (0 based) index of the first entry to move |
| * @param moveTo The (0 based) index of the positition to move to |
| * @param numToMove The number of entries to move |
| */ |
| public static void arrayMoveWithin(Object[] array, int moveFrom, int moveTo, int numToMove) { |
| // If we're not asked to do anything, return now |
| if(numToMove <= 0) { return; } |
| if(moveFrom == moveTo) { return; } |
| |
| // Check that the values supplied are valid |
| if(moveFrom < 0 || moveFrom >= array.length) { |
| throw new IllegalArgumentException("The moveFrom must be a valid array index"); |
| } |
| if(moveTo < 0 || moveTo >= array.length) { |
| throw new IllegalArgumentException("The moveTo must be a valid array index"); |
| } |
| if(moveFrom+numToMove > array.length) { |
| throw new IllegalArgumentException("Asked to move more entries than the array has"); |
| } |
| if(moveTo+numToMove > array.length) { |
| throw new IllegalArgumentException("Asked to move to a position that doesn't have enough space"); |
| } |
| |
| // Grab the bit to move |
| Object[] toMove = Arrays.copyOfRange(array, moveFrom, moveFrom+numToMove); |
| |
| // Grab the bit to be shifted |
| Object[] toShift; |
| int shiftTo; |
| if(moveFrom > moveTo) { |
| // Moving to an earlier point in the array |
| // Grab everything between the two points |
| toShift = Arrays.copyOfRange(array, moveTo, moveFrom); |
| shiftTo = moveTo + numToMove; |
| } else { |
| // Moving to a later point in the array |
| // Grab everything from after the toMove block, to the new point |
| toShift = Arrays.copyOfRange(array, moveFrom+numToMove, moveTo+numToMove); |
| shiftTo = moveFrom; |
| } |
| |
| // Copy the moved block to its new location |
| System.arraycopy(toMove, 0, array, moveTo, toMove.length); |
| |
| // And copy the shifted block to the shifted location |
| System.arraycopy(toShift, 0, array, shiftTo, toShift.length); |
| |
| |
| // We're done - array will now have everything moved as required |
| } |
| |
| } |