Android game development 2-circle collision

Collision is a very important part. Let me briefly introduce it. Circleactivity Code ; Package yy. circle; import android. app. activity; import android. OS. bundle; import android. view. view; import android. view. window; import android. view. windowmanager; public class circleactivity extends activity {/** called when the activity is first created. * // @ override public void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); this. requestwindowfeature (window. feature_no_title ); This. getwindow (). setflags (windowmanager. layoutparams. flag_fullscreen, windowmanager. layoutparams. flag_fullscreen); setcontentview (new circle (this) ;}} circle code; Package yy. circle; import android. content. context; import android. graphics. canvas; import android. graphics. color; import android. graphics. paint; import android. graphics. paintflagsdrawfilter; import android. view. keyevent; import android. view. m Otionevent; import android. view. surfaceholder; import android. view. surfaceview; import android. view. surfaceholder. callback; public class circle extends surfaceview implements callback, runnable {private surfaceholder SFH; private paint; private thread; private Boolean flag; private canvas; private int screenw, screenh; // Private bitmap BMP; private int X1 = 20, Y1 = 20, R1 = 20; private int X2 = 50, y2 = 50, R2 = 20; private Boolean iscollsion; private paintflagsdrawfilter PFD = new paintflagsdrawfilter (0, paint. anti_alias_flag | paint. filter_bitmap_flag); Public circle (context) {super (context); SFH = This. getholder (); SFH. addcallback (this); paint = new paint (); paint. setcolor (color. white); paint. setantialias (true); // BMP = bitmapfactory. decoderesource (this. getresources (), R. drawable. icon); s Etfocusable (true);} public void surfacecreated (surfaceholder holder) {screenw = This. getwidth (); screenh = This. getheight (); flag = true; thread = new thread (this); thread. start ();} public void mydraw () {try {canvas = SFH. lockcanvas (); If (canvas! = NULL) {canvas. setdrawfilter (PFD); canvas. drawcolor (color. black); If (iscollsion) {paint. setcolor (color. red); paint. settextsize (20); canvas. drawtext ("collision! ", Paint);} else {paint. setcolor (color. white);} canvas. drawcircle (x1, Y1, R1, paint); canvas. drawcircle (X2, Y2, R2, paint); // canvas. drawbitmap (BMP, 100,100, paint) ;}} catch (exception e) {} finally {If (canvas! = NULL) {SFH. unlockcanvasandpost (canvas) ;}} public Boolean ontouchevent (motionevent event) {x1 = (INT) event. getx ()-R1; Y1 = (INT) event. gety ()-R1; If (iscollsionwithcircle (x1, Y1, R1, X2, Y2, R2) {iscollsion = true;} else {iscollsion = false;} return true ;} private Boolean iscollsionwithcircle (INT X1, int Y1, int R1, int X2, int Y2, int R2) {/* If (x1> = X2 & x1> = x2 + r2 + R1) {return false ;} else if (X1 <= X2 & X1 + R1 + R2 <= x2) {return false ;} else if (Y1> = Y2 & Y1> = y2 + r2 + R1) {return false ;} else if (Y1 <= Y2 & Y1 + R1 + R2 <= Y2) {return false;} */If (R1 + R2) * (R1 + R2) <= (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) {return false;} return true;} public Boolean onkeydown (INT keycode, keyevent event) {return Super. onkeydown (keycode, event);} public void logic () {} public void run () {While (FLAG) {long start = system. currenttimemillis (); mydraw (); logic (); long end = system. currenttimemillis (); try {If (end-start <50) {thread. sleep (50-(end-Start);} catch (interruptedexception e) {e. printstacktrace () ;}} public void surfacechanged (surfaceholder holder, int format, int width, int height) {} public void surfacedestroyed (surfaceholder holder) {flag = false ;}}