To store the maximum frequency so far
int max_freq = 0 ; for ( int j = 0 ; j < ( str . length ) ; j ++ ) { if ( freq . containsKey ( str [ j ] ) ) { freq . put ( str [ j ] , freq . get ( str [ j ] ) + 1 ) ; if ( freq . get ( str [ j ] ) > max_freq ) max_freq = freq . get ( str [ j ] ) ; } else { freq . put ( str [ j ] , 1 ) ; if ( freq . get ( str [ j ] ) > max_freq ) max_freq = freq . get ( str [ j ] ) ; } }