How to concat two string arrays in Java

Alternatevely you can do it this way

    String[] a3 = Arrays.copyOf(a1, a1.length + a2.length);
    System.arraycopy(a2, 0, a3, a1.length, a2.length);

This code should work. Not as pretty as the ArrayUtils.addAll(), but functional. You also can avoid having to import anything and you won't need to ship a 3rd party library for just one function.

String[] both = new String[a1.length + a2.length];
System.arraycopy(a1,0,both,0, a1.length);
System.arraycopy(a2,0,both,a1.length + 1, a2.length);

Download common.codec-1.9.jar (Download zip and extract you will find the jar file) then if you are using an IDE like

Eclipse:

1.Right-click your Project.

2.Select Properties.

3.On the left-hand side click java build path.

4.Under Libraries Tab, click Add External Jars button.

5.Choose the downloaded file and click ok

Netbeans :

1.Right-click your Project.

2.Select Properties.

3.On the left-hand side click Libraries.

4.Under Compile tab - click Add Jar/Folder button.

Add right Maven dependency to your POM:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.3.2</version>
</dependency>

Why don't you do a for loop and store all the elements to one String and then use .split ?

String result = null;
for(String aux : a1){
   final += aux + ";";
}

for(String aux1 : a2){
   final += aux1 + ";";
}
String[] finalArray= result.split(";");

I made this out of the paper, but I'm almost sure it will work ;)

I found that the easiest way to avoid all those startingIndex and endingIndex parameters in arrayCopy() and copyOf() is to write a specific method (which is straightforward):

public static String[] concatTwoStringArrays(String[] s1, String[] s2){
    String[] result = new String[s1.length+s2.length];
    int i;
    for (i=0; i<s1.length; i++)
        result[i] = s1[i];
    int tempIndex =s1.length; 
    for (i=0; i<s2.length; i++)
        result[tempIndex+i] = s2[i];
    return result;
}//concatTwoStringArrays().

So here's the usage of concatTwoStringArrays() method:

String[] s3 = concatTwoStringArrays(s1, s2);