我需要在Java中连接两个字符串数组。

void f(String[] first, String[] second) {
    String[] both = ???
}

哪种方法最简单?


当前回答

一种简单但低效的方法(不包括泛型):

ArrayList baseArray = new ArrayList(Arrays.asList(array1));
baseArray.addAll(Arrays.asList(array2));
String concatenated[] = (String []) baseArray.toArray(new String[baseArray.size()]);

其他回答

public int[] mergeArrays(int [] a, int [] b) {
    int [] merged = new int[a.length + b.length];
    int i = 0, k = 0, l = a.length;
    int j = a.length > b.length ? a.length : b.length;
    while(i < j) {
        if(k < a.length) {
            merged[k] = a[k];
            k++;
        }
        if((l - a.length) < b.length) {
            merged[l] = b[l - a.length];
            l++;
        }
        i++;
    }
    return merged;
}

怎么样:

public String[] combineArray (String[] ... strings) {
    List<String> tmpList = new ArrayList<String>();
    for (int i = 0; i < strings.length; i++)
        tmpList.addAll(Arrays.asList(strings[i]));
    return tmpList.toArray(new String[tmpList.size()]);
}
Object[] mixArray(String[] a, String[] b)
String[] s1 = a;
String[] s2 = b;
Object[] result;
List<String> input = new ArrayList<String>();
for (int i = 0; i < s1.length; i++)
{
    input.add(s1[i]);
}
for (int i = 0; i < s2.length; i++)
{
    input.add(s2[i]);
}
result = input.toArray();
return result;

我认为泛型的最佳解决方案是:

/* This for non primitive types */
public static <T> T[] concatenate (T[]... elements) {

    T[] C = null;
    for (T[] element: elements) {
        if (element==null) continue;
        if (C==null) C = (T[]) Array.newInstance(element.getClass().getComponentType(), element.length);
        else C = resizeArray(C, C.length+element.length);

        System.arraycopy(element, 0, C, C.length-element.length, element.length);
    }

    return C;
}

/**
 * as far as i know, primitive types do not accept generics 
 * http://stackoverflow.com/questions/2721546/why-dont-java-generics-support-primitive-types
 * for primitive types we could do something like this:
 * */
public static int[] concatenate (int[]... elements){
    int[] C = null;
    for (int[] element: elements) {
        if (element==null) continue;
        if (C==null) C = new int[element.length];
        else C = resizeArray(C, C.length+element.length);

        System.arraycopy(element, 0, C, C.length-element.length, element.length);
    }
    return C;
}

private static <T> T resizeArray (T array, int newSize) {
    int oldSize =
            java.lang.reflect.Array.getLength(array);
    Class elementType =
            array.getClass().getComponentType();
    Object newArray =
            java.lang.reflect.Array.newInstance(
                    elementType, newSize);
    int preserveLength = Math.min(oldSize, newSize);
    if (preserveLength > 0)
        System.arraycopy(array, 0,
                newArray, 0, preserveLength);
    return (T) newArray;
}

您可以尝试连接多个数组的方法:

public static <T> T[] concatMultipleArrays(T[]... arrays)
{
   int length = 0;
   for (T[] array : arrays)
   {
      length += array.length;
   }
   T[] result = (T[]) Array.newInstance(arrays.getClass().getComponentType(), length) ;

   length = 0;
   for (int i = 0; i < arrays.length; i++)
   {
      System.arraycopy(arrays[i], 0, result, length, arrays[i].length);
      length += arrays[i].length;
   }

   return result;
}