I'm trying to add multiple String arrays into a single array using apache commons ArrayUtils as below but it's saying unable to convert Serializable array to String array
// assigning strings arrays
String str1[] = {"hello"};
String str2[] = {"test1"};
String str3[] = {"test2"};
String str4[] = {"hello"};
String str5[] = {"test4"};
String str6[] = {"hello"};
//joining string arrays
String[] allArrays = ArrayUtils.addAll(str1, str2, str3, str4, str5,str6);
If you want to concatenate multiple Arrays containing multiple values you can do it in one line using Java 8 streams.
String[] s1 = new String[]{"a", "b", "c"};
String[] s2 = new String[]{"d", "e", "f"};
String[] s3 = new String[]{"g", "h", "i"};
//one liner:
String[] result = Stream.of(s1, s2, s3).flatMap(Stream::of).toArray(String[]::new);
This technique was taken from mkyong.com
You can use ArrayUtils.addAll in two ways:
String[] arr1 = {"Hello", "Bye"};
String[] arr2 = {"Good", "Bad"};
String[] usage1 = ArrayUtils.addAll(arr1, arr2);
String[] usage2 = ArrayUtils.addAll(arr1, "New item", "Another item");
The first parameter is an array. The second parameter can be either an array or single items to append to first array.
ArrayUtils.addAll(Object[] array1, Object[] array2) takes only two arguments and returns new array contains all of the element of array1 followed by all of the elements array2.
You can use ArrayUtils.addAll() iteratively, but this causes a performance impact since each time a new copy of the array is created.
String[] allArrays = ArrayUtils.addAll(ArrayUtils.addAll(ArrayUtils.addAll(str1, str2), ArrayUtils.addAll(str3, str4)), ArrayUtils.addAll(str5,str6));
addAlldoesn't take variable number of arrays. It takes two arrays.