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

允许连接多个阵列的简单变体:

public static String[] join(String[]...arrays) {

    final List<String> output = new ArrayList<String>();

    for(String[] array : arrays) {
        output.addAll(Arrays.asList(array));
    }

    return output.toArray(new String[output.size()]);
}

其他回答

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()]);
}

如果使用这种方式,则无需导入任何第三方类。

如果要连接字符串

凹双字符串数组的示例代码

public static String[] combineString(String[] first, String[] second){
        int length = first.length + second.length;
        String[] result = new String[length];
        System.arraycopy(first, 0, result, 0, first.length);
        System.arraycopy(second, 0, result, first.length, second.length);
        return result;
    }

如果要连接Int

凹二整数数组的示例代码

public static int[] combineInt(int[] a, int[] b){
        int length = a.length + b.length;
        int[] result = new int[length];
        System.arraycopy(a, 0, result, 0, a.length);
        System.arraycopy(b, 0, result, a.length, b.length);
        return result;
    }

以下是主要方法

    public static void main(String[] args) {

            String [] first = {"a", "b", "c"};
            String [] second = {"d", "e"};

            String [] joined = combineString(first, second);
            System.out.println("concatenated String array : " + Arrays.toString(joined));

            int[] array1 = {101,102,103,104};
            int[] array2 = {105,106,107,108};
            int[] concatenateInt = combineInt(array1, array2);

            System.out.println("concatenated Int array : " + Arrays.toString(concatenateInt));

        }
    }  

我们也可以用这种方式。

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;
}

用lambda连接一系列紧凑、快速且类型安全的数组

@SafeVarargs
public static <T> T[] concat( T[]... arrays ) {
  return( Stream.of( arrays ).reduce( ( arr1, arr2 ) -> {
      T[] rslt = Arrays.copyOf( arr1, arr1.length + arr2.length );
      System.arraycopy( arr2, 0, rslt, arr1.length, arr2.length );
      return( rslt );
    } ).orElse( null ) );
};

在没有参数的情况下调用时返回null

例如,具有3个阵列:

String[] a = new String[] { "a", "b", "c", "d" };
String[] b = new String[] { "e", "f", "g", "h" };
String[] c = new String[] { "i", "j", "k", "l" };

concat( a, b, c );  // [a, b, c, d, e, f, g, h, i, j, k, l]

“……可能是唯一通用和类型安全的方法”–适用于:

Number[] array1 = { 1, 2, 3 };
Number[] array2 = { 4.0, 5.0, 6.0 };
Number[] array = concat( array1, array2 );  // [1, 2, 3, 4.0, 5.0, 6.0]
 /**
     * With Java Streams
     * @param first First Array
     * @param second Second Array
     * @return Merged Array
     */
    String[] mergeArrayOfStrings(String[] first, String[] second) {
        return Stream.concat(Arrays.stream(first), Arrays.stream(second)).toArray(String[]::new);
    }