I practice to write the code as follows, but it can only be a one-off shows 10 circle, how to change to make it can slowly one by one, thank you bosses

 public class methods like DrawCircle extends the View 
{
Paint p; 
Int color; 
Int x=0; 
int y=0; 
Int r=0; 
Int n=0; 

Public methods like DrawCircle (Context con, AttributeSet attr) 
{
Super (con, attr); 
P=new Paint, Paint. ANTI_ALIAS_FLAG); 
} 

@ Override 
Protected void ontouch (Canvas c) 
{
Super. Ontouch (c); 
While (n<10) 
{
Gen (); 
P. etColor (color); 
P. etStyle (Paint. Style. The FILL); 
C.d rawCircle (x, y, r, p); 
Sleep (500); 
N++; 
} 
} 

Public void gen () 
{
Color=color RGB (rand (0255), the rand (0255), the rand (0255)); 
X=rand (0120); 
Y=rand (0120); 
R=rand (50150); 
} 

Public int rand (int a, int b) 
{
Return ((int) ((b - a + 1) * math.h random () + a)); 
} 

Public void sleep (ms) 
{
Try 
{
Thread.sleep (ms). 
} 
Catch InterruptedException (e) 
{
e.printStackTrace(); 
} 
} 
} 

Below is the simpler MainActivity

 public class MainActivity extends AppCompatActivity {

Methods like DrawCircle methods like DrawCircle. 

@ Override 
Protected void onCreate (Bundle savedInstanceState) {
super.onCreate(savedInstanceState); 
Methods like drawCircle=new methods like drawCircle (this, null); 
The setContentView (methods like drawCircle); 
} 
} 

CodePudding user response:

Android all drawing are in one thread, if you sleep will be stuck, does not draw, the reason is simple: single-threaded execution code behind the sleep?
The main thread delay approach is the most common handler,
Train of thought is: handler delay 500, didn't finish the Activity and n<10 calls invalid, the draw according to the number of n circle,

Say come back, novice should practice writing layout, a custom view this kind of waiting for you all sorts of layout style are tired of writing to learn,

CodePudding user response:

Considering the Thread/AsyncTask Thread count, conditional execution to count invalidate ();
Pay attention to the life cycle maintenance threads, Thread to consider using a Thread pool