Assignment   1  SOLUTION

Assignment   1 SOLUTION



The   goals   of   this   assignment   are   to   get   your   development   environment   set   up   and   to   provide    experience   with   using   loops   and   conditionals   in   Java   and   with   building   a   simple   executable   Java    application.    Write   a   Java   program   which   sums   a   list   of   positive   integers   entered   by   the   user.     To   accomplish    this,   you’ll   repeatedly   prompt   the   user   to   enter   an   integer   and   use   special-­‐case   integer   values    to   determine   when   to   print   the   sum,   clear   the   sum,   and   quit   the   application.     You   may   get   user    input   either   from   the   console   or   by   writing   a   simple   UI.     We’ll   go   over   the   former   method   in    class.     Your   program   should:   
1.   [10]   Display   text   asking   the   user   to   enter   an   integer.     You   should   indicate   to   the   user   that    entering   -­‐1   will   print   the   current   sum,   -­‐2   will   reset   the   current   sum,   and   -­‐3   will   quit   the    application.   For   example:    Enter a positive integer (-1 to print, -2 to reset, -3 to exit):   

2.   [15]   Read   an   integer   from   the   user.  

  3.   [15]   If   the   user   entered   -­‐1,   print   the   current   sum   and   then   prompt   the   user   for   another    integer.  

  4.   [15]   If   the   user   entered   -­‐2,   set   the   current   sum   back   to   0   and   then   prompt   the   user   for    another   integer.   

5.   [15]   If   the   user   entered   -­‐3,   print   the   sum   and   then   quit   the   application.  
  
6.   [15]   If   the   user   entered   a   positive   integer,   add   it   to   the   sum   and   then   prompt   the   user   for    another   integer.  

  7.   [15]   If   the   user   entered   a   negative   number   less   than   3,   simply   ignore   the   number   and   then    prompt   the   user   for   another   integer.     It’s   worth   noting   that   your   application   will   likely   crash   if    the   user   enters   text   that   cannot   be   parsed   as   an   integer   (depending   on   your   input   method).      We   will   cover   this   later   in   the   term,   so   handling   this   case   is   not   required   (see   extra   credit).  

  8.   [+10]   (Extra   credit)   Allow   the   user   to   enter   non-­‐integer   input   without   crashing   the    application.   ☺     Hint:   you’ll   likely   need   to   use   a   try/catch   block,   which   is   covered   in   chapter   7   of    the   text.    Here’s   output   from   a   sample   run:      Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  1  Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  2 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  3 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -1 Sum: 6 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  4 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -1 Sum: 10 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -2 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -1 Sum: 0 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  1 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -1 Sum: 1 Enter a positive integer (-1 to print, -2 to reset, -3 to exit):  -3 Sum: 1 Zip   the   Assignment1   folder   in   your   Eclipse   workspace   directory   and   upload   the   .zip   file   to    Blackboard   (see   Assignments   section   for   submission   link).
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