Why can't Java resolve the variable in this for each loop? -


in following each loop, "bird cannot resolved" error @ lines marked !. have setup interface bird implemented abstract class birdtype of cardinal, hummingbird, bluebird, , vulture children. getcolor() , getposition() methods defined in abstract class while fly() unique each of child classes. client code provided professor test interface/inheritance relations have setup. note have tested interface, abstract class , child classes , seem work. think issue for-each loop can provide code other classes if needs be. advice?

import java.awt.*; public class aviary {     public static final int size = 20;     public static final int pixels = 10;      public static void main(string[] args){         //create drawing panel         drawingpanel panel = new drawingpanel(size*pixels,size*pixels);         //create pen         graphics g = panel.getgraphics();          //create birds         bird[] birds = {new cardinal(7,4), new cardinal(3,8),             new hummingbird(2,9), new hummingbird(16,11),             new bluebird(4,15), new bluebird(8,1),             new vulture(3,2), new vulture(18,14)};          while (true){             //clear screen             g.setcolor(color.white);             g.fillrect(0, 0, size*pixels, size*pixels);              //tell birds fly , redraw birds             (bird bird : birds)                  bird.fly(); !               g.setcolor(bird.getcolor()); !               point pos = bird.getposition();                 g.filloval((int)pos.getx()*pixels, (int)pos.gety()*pixels,                     pixels, pixels);                 panel.sleep(500);         }     } }

you need wrap body want executed in for loop in braces

for (bird bird : birds) {     bird.fly();     g.setcolor(bird.getcolor());     point pos = bird.getposition();     g.filloval((int)pos.getx()*pixels, (int)pos.gety()*pixels,     pixels, pixels);     panel.sleep(500); }

otherwise, body of for loop next statement following ). equivalent to

for (bird bird : birds)      bird.fly();  // bird not in scope anymore g.setcolor(bird.getcolor()); point pos = bird.getposition(); g.filloval((int)pos.getx()*pixels, (int)pos.gety()*pixels, pixels, pixels); panel.sleep(500);

as darien has said in comments, indentation not part of java language, has no bearing on syntax. should use make code easier read, expressed in java code style conventions.


-

Comments

Post a Comment

Popular posts from this blog

html - Sizing a high-res image (~8MB) to display entirely in a small div (circular, diameter 100px) -

first of all, thank being patient know simple question more couple of weeks' experience figure out. i've seen folks persevere , helpful on here , hope you're willing me. here fiddle: http://jsfiddle.net/65uzf/ here 1 of places searched answers on here: ( vertically center image thumbnails fix-sized div ) tried solutions on there , didn't work out me. i've searched ~4 or 5 others, , been unsuccessful those, too. what want take large image (what linked background-image #ysypic , #tabpic divs) , display thumbnail version of image in confines of divs have set it. is, using background properties have laid out in css, portion of image displays inside of circular divs. without these properties, display defaults smaller section of image [presumably pi*(50^2) area in top left] terrible resolution. i not care if entire image doesn't display inside of circles (it won't, given difference in shape), , overflow not being displayed fine. want able see figu
Read more

java - IntelliJ - No such instance method -

using intellij's 12 ultimate, i'm running following code in debugger: java import play.api.libs.json.jsvalue; public class foo { ... public jsvalue tojson() { ... } public class fooexample { ... foo foo = new foo(); system.out.println("...); //<-- breakpoint at breakpoint, right-clicked source code , picked "evaluate expression," typing in: foo.tojson() . but following error showed up: no such instance method: play.api.libs.json.jsvalue$class.com.foo.foo.tojson () am doing wrong? foo#tojson calls scala code, if matters. edit had breakpoint after instantiation of foo. downvoted it, deserved it. edit my answer no longer valid after op modified question (i.e. moved breakpoint actual is).. a breakpoint hit before line executed. in case foo has not yet been declared or instantiated (i.e. foo constructor has not yet been called). you'll need put breakpoint @ next line (or step on current line) if want evaluate foo .
Read more

identifier - Is it possible for an html5 document to have two ids? -

i wondering if html5 element can have 2 ids, this: <button id="thing1" id="thing2" name="button1" onclick="change()">click here</button> or this: <button id="thing1, thing2" name="button1" onclick="change()">click here</button> also, if 1 of ids said 1 thing, , other id said thing, 1 used? tl;dr : no. in versions of html, each element can have 1 id. see the spec : the id attribute specifies element's unique identifier (id). [dom] the value must unique amongst ids in element's home subtree , must contain @ least 1 character. the value must not contain space characters. note: there no other restrictions on form id can take; in particular, ids can consist of digits, start digit, start underscore, consist of punctuation , etc. note: element's unique identifier can used variety of purposes, notably way link specific parts of document usin
Read more