Android EventHandling

8/10/2019 Android EventHandling

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ANDROID EVENT

HANDLING

L. Grewe


2/17

Widget : Views that have

events For a ist o! the widgets "rovided #$ Android%see the android.widget "a&'age.

(o)e E*a)"es

+,tton -he&'+o* Datei&'er EditTe*t I)ageView (ear&hView ("inner


3/17

Event Handing

De&ide what Widgets who/s events to "ro&ess Defne an event listener and register it

with the View.

View.On-i&'Listener 0!or handing 1&i&'s1 on aView2% View.OnTo,&hListener 0!or handing to,&hs&reen events in a View2% andView.On3e$Listener 0!or handing devi&e 'e$"resses within a View2

http://developer.android.com/guide/topics/ui/ui-events.html details more


4/17

4sing E&i"se 55ets re&a o,r e*a)"e!ro) o,r starting e&t,re

6Heo Word ro7e&t8 Lets add a #,tton


5/17

Lets add a +,tton to a

"rogra)5#ased inter!a&e (te" 9: Add #,tton (te" : Register Event Hander

TWO OTION( se"arate &ass to hande

event0s2% OR have the A&tivit$ &ontaining the#,tton do the event handing

(te" ;: I)"e)ent Event Hander


6/17

Event handing done #$

A&tivit$ itse! Here &ode to hande is inside A&tivit$ itse! ",#i& &ass E*a)"eA&tivit$ e*tends A&tivit$ i)"e)ents On-i&'Listener=

"rote&ted void on-reate0+,nde savedVa,es2 =

...

+,tton #,tton ? 0+,tton2@ndView+$Id0R.id.&or'$2 //STEP 1 #,tton.setOn-i&'Listener0this2 //STEP - registration B

CC I)"e)ent the On-i&'Listener &a#a&' //STEP ! "event handler ",#i& void on-i&'0View v2 =

CC do so)ething when the #,tton is &i&'ed B ...B


7/17

Event Handing 5 here have

a (EARATE &assEVE#T $%#D&'#( )*DE in separate o+,ect m)or&istner CC -reate an anon$)o,s i)"e)entation o! On-i&'Listener STEP !

"rivate On-i&'Listener )-or'$Listener ? new On-i&'Listener02 = ",#i& void on-i&'0View v2 = CC do so)ething when the #,tton is &i&'ed

BB

CCNow inside $o,r A&tivit$ &ass"rote&ted void on-reate0+,nde savedVa,es2 = ...

// STEP 1: -a"t,re o,r #,tton !ro) a$o,t +,tton #,tton ? 0+,tton2@ndView+$Id0R.id.&or'$2 // STEP : Register the on-i&' istener with the i)"e)entation a#ove #,tton.setOn-i&'Listener0)-or'$Listener2 ...B


8/17

De"ends on IDE


9/17

(TE9: -reate a +,tton

-reate #,tton,sing L G4Iinter!a&e in E&i"se

(et "ro"ert$ soa#e on #,tton is6Hit e8

Aso% added te*tview withinstr,&tions teing,ser to hit #,tton


10/17

(TE: Register the )ainA""i&ation A&tivit$ as

EventHander !or #,tton Gra# #,tton asso&iated with its id% store ino&a varia#e #.

-a seton-i&'Listener0this2pu+lic class %ndroidEample0Event$adling%ctivit etends %ctivit implements *n)lic&istener

int hits 234

C -aed when the a&tivit$ is @rst &reated. C

Override

pu+lic void on)reate56undle saved'nstanceState7

super.on)reate5saved'nstanceState74

set-ontentView0R.a$o,t.main);

+,tton # ? 0+,tton2@ndView+$Id0R.id.button1);

#.setOn-i&'Listener0this74

B


11/17

(TE: Register the )ainA""i&ation A&tivit$ as

EventHander !or #,tton Have the )ain &ass 6AndroidE*a)"eeventHandingA&tivit$8i)"e)ent On-i&'Listener !or #,tton

In )ethod on-i&' in&re)ent hits and ,se in dis"a$ string.pu+lic class %ndroidEample0Event$adling%ctivit etends %ctivit implements *n)lic&istener

int hits 234

C -aed when the a&tivit$ is @rst &reated. C

Override

pu+lic void on)reate56undle saved'nstanceState7

//see previous slide88..

B

CC I)"e)ent the On-i&'Listener &a#a&'

CC(TE ; event hander

pu+lic void on)lic5View v7

CC do so)ething when the #,tton is &i&'ed

this.hits994

Te*tView te*t ? 0Te*tView2@ndView+$Id0R.id.textView1);

(tring s ? 1Jo, hit )e 1 K this.hits4

te*t.setTe*t0s2

B

B


12/17

Lets r,n the "revio,s &ode.

R,n $o,r &ode


13/17

A!ter r,nning it#e!ore hit

#,tton


14/17

A!ter hitting #,tton a !ew

ti)es


15/17


16/17

Re)e)#er


17/17

Android EventHandling

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