Create a boolean array " prime [ 0 . . n ] " and initialize all entries it as true . A value in prime [ i ] will finally be false if i is Not a prime , else true .
boolean [ ] prime = new boolean [ MAX ] ; for ( int i = 0 ; i < MAX ; i ++ ) prime [ i ] = true ; for ( int p = 2 ; p * p < MAX ; p ++ ) {