java - Applying key bindings to state transitions when implementing a state pattern -

-

here's programming style question best strategy map input keys actions in class implement state pattern.

i'm dealing 2 classes:

the first implements state pattern, controls multi-state physical device:

class devicecontroller {     state _a, _b, _current;      // actions may prompt transition 1 state     public void actiona() { ... }     public void actionb() { ... }     public void actionc() { ... }      public state getstatea() { ... }     public state getstateb() { ... }      public void setcurrentstate() { ... } };

the second keylistener retrieves keyboard input , calls appropriate action device controller when pressed input key matches (for time being) hard-coded bindings table:

class keydemo implements keylistener {      devicecontroller _controller;     ...     @override     public void keypressed(keyevent arg0) {         char key = character.touppercase(arg0.getkeychar());         switch (key) {         case 'a':             _controller.actiona();             break;         case 'b' :         ...     }     ... }

is there best-practice coding style bind keys actions in controller ? have go through switch statement, in sample code ? seems me solution dirty code: isn't state pattern supposed eliminate unmaintanable if , switch control structures ?

thank suggenstions.

using polymorphism can achive goal. i've used enum maybe more appropriated use interfaces or abstract class , implement each of key processors. think?

import java.awt.event.keyevent; import java.awt.event.keylistener;  enum keyprocessor {     {         void executeaction() {             _controller.actiona();         }     },     b {         void executeaction() {             _controller.actionb();         }     };      private static final devicecontroller _controller = new devicecontroller();      void executeaction() {         system.out.println("no action defined");     } }  class devicecontroller {     state _a;     state _b;     state _current;      // actions may prompt transition 1 state     public void actiona() {         system.out.println("action performed.");      }      public void actionb() {         system.out.println("action b performed.");     }      public void actionc() {     }      public state getstatea() {         return null;     }      public state getstateb() {         return null;     }      public void setcurrentstate() {     } } // end class devicecontroller  public class keydemo implements keylistener {      devicecontroller _controller;      // ...     @override     public void keypressed(keyevent arg0) {         keypressed(character.touppercase(arg0.getkeychar()));         // ...     }      public void keypressed(char c) {         keyprocessor processor = keyprocessor.valueof(c + "");         if (processor != null) {         processor.executeaction();     }      }      @override     public void keytyped(keyevent e) {     }      @override     public void keyreleased(keyevent e) {     }      public static final void main(string[] args) {         keydemo main = new keydemo();         main.keypressed('a');         main.keypressed('b');     } } // end class keydemo  class state { }

Comments

Post a Comment

Popular posts from this blog

c# - How to set Z index when using WPF DrawingContext? -

-
how set z-index drawing object when using drawingcontext.drawxxx() methods? the object drawn last have higher z index. can't change index of drawn objects. way draw in order. if using wpf (as placed tag), can use, example, canvas control. create shapes need like polyline obj = new polyline(); //... // ... set properties of obj and add them canvas uielementcollection: yourcanvasname.children.add(obj); //or yourcanvasname.children.insert(i, obj); first items of collection have higher z index. advantages in way: no need redraw on window changes, can anytime move objects , change order.
Read more

razor - Is this a bug in WebMatrix PageData? -

-
i think may have found bug in webmatrix's pagedata, not sure. concerns how pass data partial page calling page. in webmatrix documentation (tutorials, e.g. " 3 - creating consistent look ", , example code), pagedata recommended mechanism pass data between pages (e.g. content page layout page, or partial page). however have found not work other way, pass data partial page calling page. modifying or adding entries in pagedata in partial page, not seem calling page. cutting right down simplest possible example, in test page may have this: @{ pagedata["test"] = "initial entry"; } <p>before calling partial page, test value @pagedata["test"]</p> @renderpage("_testpartial.cshtml") <p>after returning calling page, test value @pagedata["test"]</p> and in _testpartial.cshtml page might have this: @{ pagedata["test"] = "modified entry"; } <p>in partial page...
Read more

visual c++ - Using relative values in array sorting ( asm ) -

-
i need sort through array , sort each individual row in array in ascending order. doesn't seem going (surprise!) keep getting hit 2 errors: a2101: cannot add 2 relocatable labels , a2026: constant expected here's sort, makes sense me, think i'm still trying implement high-lvl language techniqes assembly. there way around not being able use relative values? (the array 7 rows 9 columns, btw). mov cx, 7; cx = number of rows outer: ; outer loop walk through rows push cx mov cx, 9 mov row, cx ;rows middle: ; middle-loop walk through columns push cx sub cx, 1 ;cx = cx-1 mov column, cx ;columns inner: ;inner loop - compare , exchange column values cmp marray[row*9 + column], marray[row*9 + column+1] xchg marray[row*9 + column+1], marray[row*9 + column] ; compare , exchange values marray table inc column loop inner pop cx loop mid...
Read more