Joining contents in multiple lines to a single line

I do have a file with contents splited into multiple lines

ADSLHLJASHGLJSKAGHJJGAJSLGAHLSGHSAKBV
AJHALHALHGLAGLHGBJVFBJVLFDHADAH
GFJAGJAGAJFGAKGAKGFAK
AJHFAGAKAGAGKAKAKGKAGFGJDGDJJDGJDJDFAG
...
...
....
100's of lines

I would like to rearrange the content of this file so it will be a single line

ADSLHLJASHGLJSKAGHJJGAJSLGAHLSGHSAKBVAJHALHALHGLAGLHGBJVFBJVLFDHADAHGFJAGJAGAJFGAKGAKGFAKAJHFAGAKAGAGKAKAKGKAGFGJDGDJJDGJDJDFAG

Is there an easy way to do it using sed or awk. Please let me know.

tr -d \\n < file > newfile