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[LANG-1707] Add ArrayUtils.concat methods for concatenating multiple arrays #1519

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[LANG-1707] Add ArrayUtils.concat methods for concatenating multiple arrays #1519

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256 changes: 256 additions & 0 deletions src/main/java/org/apache/commons/lang3/ArrayUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9305,6 +9305,262 @@ public static String[] toStringArray(final Object[] array, final String valueFor
return map(array, String.class, e -> Objects.toString(e, valueForNullElements));
}

/**
* Concatenates multiple boolean arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new boolean array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static boolean[] concat(boolean[]... arrays) {
int totalLength = 0;
for (boolean[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

boolean[] result = new boolean[totalLength];
int currentPos = 0;
for (boolean[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple char arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new char array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static char[] concat(char[]... arrays) {
int totalLength = 0;
for (char[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

char[] result = new char[totalLength];
int currentPos = 0;
for (char[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple byte arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new byte array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static byte[] concat(byte[]... arrays) {
int totalLength = 0;
for (byte[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

byte[] result = new byte[totalLength];
int currentPos = 0;
for (byte[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple short arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new short array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static short[] concat(short[]... arrays) {
int totalLength = 0;
for (short[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

short[] result = new short[totalLength];
int currentPos = 0;
for (short[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple int arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new int array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static int[] concat(int[]... arrays) {
int totalLength = 0;
for (int[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

int[] result = new int[totalLength];
int currentPos = 0;
for (int[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple long arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new long array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static long[] concat(long[]... arrays) {
int totalLength = 0;
for (long[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

long[] result = new long[totalLength];
int currentPos = 0;
for (long[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple float arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new float array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static float[] concat(float[]... arrays) {
int totalLength = 0;
for (float[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

float[] result = new float[totalLength];
int currentPos = 0;
for (float[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* Concatenates multiple double arrays into a single array.
*
* <p>This method combines all input arrays in the order they are provided,
* creating a new array that contains all elements from the input arrays.
* The resulting array length is the sum of lengths of all non-null input arrays.</p>
*
* @param arrays the arrays to concatenate. Can be empty, contain nulls,
* or be null itself (treated as empty varargs)
* @return a new double array containing all elements from the input arrays
* in the order they appear, or an empty array if no elements are present
*/
public static double[] concat(double[]... arrays) {
int totalLength = 0;
for (double[] array : arrays) {
if (array != null) {
totalLength += array.length;
}
}

double[] result = new double[totalLength];
int currentPos = 0;
for (double[] array : arrays) {
if (array != null && array.length > 0) {
System.arraycopy(array, 0, result, currentPos, array.length);
currentPos += array.length;
}
}

return result;
}

/**
* ArrayUtils instances should NOT be constructed in standard programming. Instead, the class should be used as {@code ArrayUtils.clone(new int[] {2})}.
* <p>
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