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 p = 0 ; p < MAX ; p ++ ) prime [ p ] = true ; prime [ 0 ] = false ; prime [ 1 ] = false ; for ( int p = 2 ; p * p < MAX ; p ++ ) {