Custom view implementations follow the finger of the ball

 Packagecom.pingyijinren.test;ImportAndroid.content.Context;ImportAndroid.graphics.Canvas;ImportAndroid.graphics.Color;ImportAndroid.graphics.Paint;ImportAndroid.util.AttributeSet;ImportAndroid.view.View;/*** Created by Administrator on 2016/5/21 0021.*/ Public classDrawviewextendsView {Private floatx=100; Private floaty=100;  PublicDrawview (Context context) {Super(context); }   //when customizing a view, you must implement the view's three constructors     PublicDrawview (Context context, AttributeSet attrs) {Super(Context,attrs); }     PublicDrawview (context context, AttributeSet attrs,intDefstyle) {        Super(Context,attrs,defstyle); } @Override Public voidOnDraw (canvas canvas) {//OnDraw is not required and can be rewritten on demand        Super. OnDraw (canvas); Paint Paint=NewPaint ();        Paint.setcolor (color.red); Canvas.drawcircle (x, Y,100, paint); }     Public voidSetX (floatx) {         This. x=x; }     Public voidSety (floaty) {         This. y=y; }}

<?xml version= "1.0" encoding= "Utf-8"? ><relativelayout xmlns:android= "http://schemas.android.com/apk/res/ Android "    xmlns:tools=" Http://schemas.android.com/tools "    android:layout_width=" Match_ Parent "    android:layout_height=" Match_parent "    tools:context=" Com.pingyijinren.test.MainActivity ">    <com.pingyijinren.test.DrawView        android:layout_width = "Wrap_content"        android:layout_height= "Wrap_content"        android:id= "@+id/ Drawview "/></relativelayout>

 Packagecom.pingyijinren.test;Importandroid.support.v7.app.AppCompatActivity;ImportAndroid.os.Bundle;ImportAndroid.util.Log;Importandroid.view.MotionEvent;ImportAndroid.view.View; Public classMainactivityextendsappcompatactivity {PrivateDrawview Drawview; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate); Try{Setcontentview (r.layout.activity_main); }        Catch(Exception e) {e.printstacktrace (); LOG.D ("Mainactivity", E.getmessage ()); } Drawview=(Drawview) Findviewbyid (R.id.drawview); Drawview.setontouchlistener (NewView.ontouchlistener () {//Drawview Responding to screen touch events@Override Public BooleanOnTouch (View V, motionevent event) {Drawview.setx (Event.getx ());                Drawview.sety (Event.gety ());                Drawview.invalidate (); return true;    }        }); }}

Custom View implements a small ball that follows your finger