I know, We can copy or append elements of array. But, I have around 100 elements in an array. Is there any other way available so I can append array to first array.
Consider I have this two arrays.
String name1[]={"abc", "def", "ghi"};
String name2[]={"jkl", "mno", "pqr"};
I want to append name2 array at the end of name1.
Please help me.
would be grateful for help.
Guava provides Arrays.concat(T[], T[], Class<T>).
The reason for the Class parameter, FYI, is because generic arrays have a distinct tendency to get upcast. If you did Arrays.concat(Integer[], Long[]), did you want an Object[] back? Or a Number[]? Guava makes you specify so there's no ambiguity...and because all of the alternatives can lead to unpredictable ClassCastExceptions at runtime.
(Disclosure: I contribute to Guava.)
ArrayUtils will just give you an Object[], which you might be able to cast with an unsafe warning, but that is unsafe: it might lead to unpredictable ClassCastExceptions later.)You will have to create a new array.
An easy implementation using generics and not using any external library:
public static void main(String[] args) {
String [] a1 = { "a", "b" };
String [] a2 = { "c", "d", "e", "f" };
System.out.println(Arrays.toString(append(a1, a2)));
}
public <K> K[] append(K[] a1, K[] a2) {
K[] a1a2 = Arrays.copyOf(a1, a1.length + a2.length);
for (int i = a1.length; i < a1a2.length; i++) {
a1a2[i] = a2[i - a1.length];
}
return a1a2;
}
OBS: As Louis Wasserman comments in his answer, Java will upcast the arrays, which can be a problem. For example, if you provide a Long[] and an Integer[] to the append method above, it will compile but you will get a java.lang.ArrayStoreException at run-time!!
You will have to create a new array. Because the length of arrays is fixed.
String[] list = new String[name1.length+name2.length]
You could loop around the two arrays and add each element to the new array
You could also use apache commons lang library
String[] both = ArrayUtils.addAll(first, second);
String[].