1.Object.clone()
简单直接，只能对源数组完整地复制
2.Arrays.copyOf(T[] original, int newLength)
可以只复制源数组中部分元素，但复制的起始位置固定为0
3.Arrays.copyOfRange(T[] original, int from, int to)
可以指定复制的起始位置
4.System.arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
复杂，但可以将源数组中的部分元素复制到目标数组的指定位置（此方法最灵活，可实现上述1、2、3的功能）
1、2、3都具有一定的局限性（返回一个新的数组，无法将源数组中的元素复制到已存在的数组中），
故合并数组的操作只能通过System.arraycopy来完成，以下为示例：
JApp.java
import static java.lang.System.out;
import java.lang.reflect.Array; public class JApp { //没有使用Java中预定义的函数
// private static int[] mergeArrays(int[]... arrays) {
// int lengthOfNewArray = 0;
// for (int i = 0; i < arrays.length; ++i) {
// lengthOfNewArray += arrays[i].length;
// }
// int[] newArray = new int[lengthOfNewArray];
// int index = 0;
// for (int[] array : arrays) {
// for (int i : array) {
// newArray[index++] = i;
// }
// }
// return newArray;
// }
private static <T> T[] mergeArrays(T[]... arrays) {
int lengthOfNewArray = 0;
for (int i = 0; i < arrays.length; ++i) {
lengthOfNewArray += arrays[i].length;
}
//使用(T[])Array.newInstance(...)可避免(T[])new Object[...]引发的ClassCastException
T[] newArray = (T[]) Array.newInstance(arrays[0].getClass().getComponentType(), lengthOfNewArray);
int destPos = 0;
for (int i = 0; i < arrays.length; ++i) {
System.arraycopy(arrays[i], 0, newArray, destPos, arrays[i].length);
destPos += arrays[i].length;
}
return newArray;
} private static int[] mergeArrays(int[]... arrays) {
int lengthOfNewArray = 0;
for (int i = 0; i < arrays.length; ++i) {
lengthOfNewArray += arrays[i].length;
}
int[] newArray = new int[lengthOfNewArray];
int destPos = 0;
for (int i = 0; i < arrays.length; ++i) {
System.arraycopy(arrays[i], 0, newArray, destPos, arrays[i].length);
destPos += arrays[i].length;
}
return newArray;
} public static void main(String[] args) {
int[] ints1 = {0, 1, 2, 3, 4};
int[] ints2 = {5, 6, 7, 8, 9};
int[] ints3 = {10, 11, 12, 13, 14};
int[] buffer = new int[ints1.length + ints2.length + ints3.length];
for (int i : buffer) {
out.print(i + " ");
}
out.println();
System.arraycopy(ints1, 0, buffer, 0, ints1.length);
System.arraycopy(ints2, 0, buffer, ints1.length, ints2.length);
System.arraycopy(ints3, 0, buffer, ints1.length + ints2.length, ints3.length);
for (int i : buffer) {
out.print(i + " ");
}
out.println();
int[] array = mergeArrays(ints1, ints2, ints3);
for (int i : array) {
out.print(i + " ");
}
out.println();
Object[] objects = mergeArrays(new Object[]{"a", "b", "c"}, new Object[]{"D", "E"}, new Object[]{"测试", "Bu Ish", "布衣食"});
for (Object o : objects) {
out.print(o + "、");
}
out.println();
String[] strings = mergeArrays(new String[]{"a", "b", "c"}, new String[]{"D", "E"}, new String[]{"测试", "Bu Ish", "布衣食"});
for (String s : strings) {
out.print(s + "、");
}
out.println();
}
}