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

哇!这里有很多复杂的答案,包括一些依赖于外部依赖的简单答案。这样做怎么样:

String [] arg1 = new String{"a","b","c"};
String [] arg2 = new String{"x","y","z"};

ArrayList<String> temp = new ArrayList<String>();
temp.addAll(Arrays.asList(arg1));
temp.addAll(Arrays.asList(arg2));
String [] concatedArgs = temp.toArray(new String[arg1.length+arg2.length]);

其他回答

使用Java 8+流,您可以编写以下函数:

private static String[] concatArrays(final String[]... arrays) {
    return Arrays.stream(arrays)
         .flatMap(Arrays::stream)
         .toArray(String[]::new);
}

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()]);
}

以下是对我有用的:

String[] data=null;
String[] data2=null;
ArrayList<String> data1 = new ArrayList<String>();
for(int i=0; i<2;i++) {
   data2 = input.readLine().split(",");
   data1.addAll(Arrays.asList(data2));
   data= data1.toArray(new String[data1.size()]);
   }

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]

在Java 8中使用流:

String[] both = Stream.concat(Arrays.stream(a), Arrays.stream(b))
                      .toArray(String[]::new);

或者像这样,使用flatMap:

String[] both = Stream.of(a, b).flatMap(Stream::of)
                      .toArray(String[]::new);

要对泛型类型执行此操作,必须使用反射:

@SuppressWarnings("unchecked")
T[] both = Stream.concat(Arrays.stream(a), Arrays.stream(b)).toArray(
    size -> (T[]) Array.newInstance(a.getClass().getComponentType(), size));