sort evenArr [ ] in ascending order sort oddArr [ ] in descending order
Collections . sort ( evenArr ) ; Collections . sort ( oddArr , Collections . reverseOrder ( ) ) ; int i = 0 ; for ( int j = 0 ; j < evenArr . size ( ) ; j ++ ) { arr [ i ++ ] = evenArr . get ( j ) ; } for ( int j = 0 ; j < oddArr . size ( ) ; j ++ ) { arr [ i ++ ] = oddArr . get ( j ) ; } }