Android Developer's practical trivia points-1

1. Remove the Actionbar from the Android screen:

1 this. requestwindowfeature (Window.feature_no_title); // Remove title bar 2 // This is a full-screen display of the code            
3 This.getwindow (). SetFlags (Windowmanager.layoutparams.flag_fullscreen,windowmanager.layoutparams.flag_ fullscreen); 3 Setcontentview (r.layout.login);

2. Disable Activity Auto Traverse: Config in re-manifest file

1 <  2     android:name= "Unitestactivity"3    android: Screenorientation= "Landscape">4</activity >

The TextView in 3.Android shows a lot of things he can't drag.

1 <ScrollView>2 <TextView3 Android:id= "@+id/text"4 Android:layout_width= "Wrap_content"5 Android:layout_height= "Wrap_content"6 Android:text= "TextView" />7 </ScrollView>

TextView a lot of content, Scroolview wrapped TextView can be dragged

The difference between 4.int and integer:

int is the basic data type integer is the wrapper class, and the default value for int is 0,integer null. Look at the need to use them

5.Spinner: (Click events and add data to Spinner)

Define an array string[] arr;

Set Arrayadapter adapter=new arrayadapter ();

First say Click event:

1 Spinner.setonitemselectlisonner () {2     toast. (This, arr[arg2]+ "was clicked", Toast. ) Long). Show (); 3 4 }

Add data to the spinner inside:
First, you define a list collection:

1 Private List<string> list;

Add all the data in Arr to the list collection:

 for (int =0;i<arr.length;i++) {Ist.add (arr)};

The button will not be added until it is clicked:

Bt.setonclicklinner (new onclicklintenner) {String str=edit.gettext (). toString (); Adapter.add (str);}}

To delete data from spinner:

Bt.setonclicklistener (new Onclicklistener) {adapter.remove (spinner.getitemselectItem.toString ());}

6. Get the size of the phone screen: The main thing is to use displaymetrics this tool;

1 displaymetrics dis =new displaymetrics ();                         // declare this class 2 Getwindowmanger (). Getdefaultdisplay (). getmetrics (dis);     // to get this kind of service accordingly 3 String str= "screen resolution is" +dis.widthpixes+dis.getheight ();  // methods for calling the DIS class directly

Simplecursoeadapter in 7.Android:

1 cursor c=db. Query (); 2 3 simplecursoradapter adapter=new simplecursoradapter (This, Android.r.layout.simplelist.item_1,c,new sting["name"],new  inte[android.r.id.text1]); 4 5 Adapter.setdropdownview (android.r.layout.pinner1); 6 7 Spinnner.setadpter (adapter);

8.Sqlite Query Detailed:

Db. query{"table name", "new string[]{" to query the column name "}", "condition",new string[]{"Convert the query condition to New string[]{string.valueof ()}"}, null. null. null};

9.Android automatically converts Web pages to clickable: Add an attribute to TextView autolink=all just fine.

10.Android Click two times to exit the program: first set a global variable Boolean exit=false; Click Back to execute a method doexit ();

1  Public BooleanOnKeyDown (keycode,keyevent) {2     if(Code = =keyevent.codeback) {3 doexit ();4     }5 }6 Private voidDoexit () {7     if(!exit) {8Toast.maketoast (Maiin. This, "quit the program at one click", Toast.Long). Show ();9Handler.sendemptymessage (1,2000);Ten}Else { OneMain. This. Finish (); A     } - } -Handler handlre=NewHandler () { the Priva Ovid Handlermessage (Messager msg) { -         Switch(msg.what) { -          Case1: -exit=false; +              Break; -         } +     } A}

11.Android determine whether to connect:

1 connvicimanger con=(Connvitimanger) Getsystem. Server (Context.conntivimanger); 2 Boolena b=con.getactiviinfo (). Isacvle (); // If the returned true is a networked

Custom dialog in 12.Android:

First define the layout of the dialog you want, have a edittext or something, write directly to layout.

Then declare the layout in the activity:

1Linaerlayout layout= (linearlayout) Layoutinflater.from ( This). Infalter (R.layout.dialog,NULL);2 3Edittext edit= (Edittext) Findviewbyid (R.id.edit);//find the EditText in the layout4 5Alertdialog.builder dialog=NewAlertdialog.builder ( This);6 7Dialog.settitle ("Ip setting");8 9 Dialog.seticon (R.drawable.icon);Ten Dialog.setview (Layout) One dialog.setmessage ..... A  -Dialog.setpronegetbutton ("",Newdialoginterface.onclicklinter) { -}

TimerTask in 13.Android: Implements the function to countdown 10 seconds and then execute a method

Define a button, a TextView and a timer:

1Button.setonclicklinster (Newonclicklinster) {2     inti=10;3TimerTask timertask=NewTimerTask () {4      Public voidrun () {5Message msg=NewMessage ();6msg.what=i--;7 handler.sendmessage (msg);8         }9     }TenTimer.hueune (timertask,1000,1000); One } A  -Handler handler=Newhanler{ -      PublicHandler message () { the         if(msg.what>0){ - Text.setext (msg.what); -}Else { -Text.settext ("End"); + Timer,.clean (); -         } +     } A}

Timers in 14.Android:

Declare a chronometer in the layout file

Instantiate in activity and use Chronometer.setbase (systemtime.realtime); This is the start time.

Chronometer.start (); Start timer

Async in 15.Android:

Inherit asynctask this class and replicate three of the methods inside him:

OnPreExecute (): The first method of execution;

Doinbackgroup (): Time-consuming operation performed;

OnPostExecute (): Prompt the user after executing the time-consuming operation;

Android Developer's practical trivia points-1