[Android] Day of development

These days because the computer's USB port has failed, has not played Android-studio

Later, after reloading the computer from Win7-Win10, a portion of the USB port can be used, and then develop Android

Next, follow the book and make a small ball that follows your finger: (I used the Android-studio to upgrade to the latest version 3.0 Beta 1)

Create a new Drawview.java class in the Mainactivity.java directory with the following code:

 Packagecom.oazzz.test7;ImportAndroid.content.Context;ImportAndroid.graphics.Canvas;ImportAndroid.graphics.Color;ImportAndroid.graphics.Paint;ImportAndroid.util.AttributeSet;Importandroid.view.MotionEvent;ImportAndroid.view.View; Public classDrawviewextendsView { Public floatCurrentX = 40;  Public floatCurrentY = 50; //defining and creating brushesPaint p =NewPaint ();  PublicDrawview (Context context) {Super(context); }     PublicDrawview (context context, AttributeSet set) {Super(context, set); } @Override Public voidOnDraw (canvas canvas) {Super. OnDraw (canvas); //set the color of a brushP.setcolor (color.red); //Draw a small circle (as a ball)Canvas.drawcircle (CurrentX, CurrentY, 15, p); }    //overriding event handling methods for touch events of this component@Override Public Booleanontouchevent (Motionevent event) {//Modify CurrentX, currenty two propertiesCurrentX =Event.getx (); CurrentY=event.gety (); //notifies the current component to redraw itselfinvalidate (); //returns true to indicate that the method has handled the event        return true; }}

Next modify the Mainactivity.java content as:

 Packagecom.oazzz.test7;ImportAndroid.os.Bundle;Importandroid.support.constraint.ConstraintLayout;Importandroid.support.v7.app.AppCompatActivity; Public classMainactivityextendsappcompatactivity {@Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); //get the LinearLayout container in the layout fileConstraintlayout root =(constraintlayout) Findviewbyid (r.id.root); //Creating Drawview Components        FinalDrawview draw =NewDrawview ( This); //set the maximum width and height of a custom componentDraw.setminimumwidth (300); Draw.setminimumheight (500);    Root.addview (Draw); }}

The r.id.root comes from the activity_main.xml:

<?XML version= "1.0" encoding= "Utf-8"?><Android.support.constraint.ConstraintLayoutxmlns:android= "Http://schemas.android.com/apk/res/android"Xmlns:app= "Http://schemas.android.com/apk/res-auto"Xmlns:tools= "Http://schemas.android.com/tools"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"Tools:context= "Com.oazzz.test7.MainActivity" android:id= "@+id/root" >    <TextViewAndroid:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "Hello world!"App:layout_constraintbottom_tobottomof= "Parent"App:layout_constraintleft_toleftof= "Parent"App:layout_constraintright_torightof= "Parent"App:layout_constrainttop_totopof= "Parent" /></Android.support.constraint.ConstraintLayout>

Only the light green part is added.

After reloading the Win10, stepping on a lot of pits, Android-studio is directly from another computer copied over to C:\Program Files\android-studio began to use. You do not need to download the installation JRE or set the environment variables in the system properties. Each time you use Android-studio, Gradle Sync's current configuration is:

[Android] Day of development