ArrayUtilpublic class ArrayUtil extends Object | Utility classes for dealing with arrays. |
| Methods Summary |
|---|
| public static void | arrayMoveWithin(java.lang.Object[] array, int moveFrom, int moveTo, int numToMove)Moves a number of entries in an array to another point in the array,
shifting those inbetween as required.
// 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 = new Object[numToMove];
System.arraycopy(array, moveFrom, toMove, 0, 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 = new Object[(moveFrom-moveTo)];
System.arraycopy(array, moveTo, toShift, 0, toShift.length);
shiftTo = moveTo + numToMove;
} else {
// Moving to a later point in the array
// Grab everything from after the toMove block, to the new point
toShift = new Object[(moveTo-moveFrom)];
System.arraycopy(array, moveFrom+numToMove, toShift, 0, toShift.length);
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
| | public static void | arraycopy(byte[] src, int src_position, byte[] dst, int dst_position, int length)This is really a debugging version of System.arraycopy().
Use it to provide better exception messages when copying arrays around.
For production use it's better to use the original for speed.
if (src_position < 0)
throw new IllegalArgumentException("src_position was less than 0. Actual value " + src_position);
if (src_position >= src.length)
throw new IllegalArgumentException( "src_position was greater than src array size. Tried to write starting at position " + src_position + " but the array length is " + src.length );
if (src_position + length > src.length)
throw new IllegalArgumentException("src_position + length would overrun the src array. Expected end at " + (src_position + length) + " actual end at " + src.length);
if (dst_position < 0)
throw new IllegalArgumentException("dst_position was less than 0. Actual value " + dst_position);
if (dst_position >= dst.length)
throw new IllegalArgumentException( "dst_position was greater than dst array size. Tried to write starting at position " + dst_position + " but the array length is " + dst.length );
if (dst_position + length > dst.length)
throw new IllegalArgumentException("dst_position + length would overrun the dst array. Expected end at " + (dst_position + length) + " actual end at " + dst.length);
System.arraycopy( src, src_position, dst, dst_position, length);
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