Problem
Write the definition of a Java method named join2files that receives three String arguments. The first two arguments name two files that exist and contain a single line. The third argument is the name of a file that doesn't yet exist. The join2files method writes the first line of each of the two files that exist to the third file, whose name is given by the third argument. The method doesn't return any value, but when it returns the third file will have two lines in it (coming from the other two files).