Java 连接合并两个数组(Array)的五种方法

1、使用泛型方法和System.arraycopy实现

T可以是基础类型，也是类类型

public static  T concatenate(T a, T b) {if (!a.getClass().isArray() || !b.getClass().isArray()) {throw new IllegalArgumentException();}Class resCompType;Class aCompType = a.getClass().getComponentType();Class bCompType = b.getClass().getComponentType();if (aCompType.isAssignableFrom(bCompType)) {resCompType = aCompType;} else if (bCompType.isAssignableFrom(aCompType)) {resCompType = bCompType;} else {throw new IllegalArgumentException();}int aLen = Array.getLength(a);int bLen = Array.getLength(b);@SuppressWarnings("unchecked")T result = (T) Array.newInstance(resCompType, aLen + bLen);System.arraycopy(a, 0, result, 0, aLen);System.arraycopy(b, 0, result, aLen, bLen);return result;}

2、使用ArrayUtils.addAll实现

String[] both = (String[])ArrayUtils.addAll(first, second);

3、不使用System.arraycopy实现

static String[] concat(String[]... arrays) {int length = 0;for (String[] array : arrays) {length += array.length;}String[] result = new String[length];int pos = 0;for (String[] array : arrays) {for (String element : array) {result[pos] = element;pos++;}}return result;}

4、使用ObjectArrays.concat实现

String[] both = ObjectArrays.concat(first, second, String.class);

5、使用Arrays.copyOf()实现

public static  T[] concatAll(T[] first, T[]... rest) {int totalLength = first.length;for (T[] array : rest) {totalLength += array.length;}T[] result = Arrays.copyOf(first, totalLength);int offset = first.length;for (T[] array : rest) {System.arraycopy(array, 0, result, offset, array.length);offset += array.length;}return result;}