Android SQLite database usage example

Android SQLite database usage example

For a brief introduction, mainstream mobile devices such as Android and iPhone all use SQLite as the storage engine for complex data. When we develop applications for mobile devices, we may need to use SQLite to store a large amount of data, so we need to master the SQLite development skills on mobile devices. For the Android platform, the system has built-in rich APIs for developers to operate SQLite. We can easily access data.

 

Now we use SQLite to develop an English dictionary. Is the project structure ......

MySQLite. java

 

Package sn. qdj. sqlitedemo; import android. content. context; import android. database. databaseErrorHandler; import android. database. sqlite. SQLiteDatabase; import android. database. sqlite. SQLiteDatabase. cursorFactory; import android. database. sqlite. SQLiteOpenHelper; import android. util. log; /*** SQLite database operation ** @ author qingdujun **/public class MySQLite extends SQLiteOpenHelper {/*** construct an SQL statement to CREATE a TABLE */final String CREATE_TABLE_ SQL = CREATE TABLE dict (uid integer primary key autoincrement, + word interge, + detail varchar); public MySQLite (Context context, String name, CursorFactory factory, int version) {super (context, name, factory, version ); // TODO Auto-generated constructor stub} public MySQLite (Context context, String name, CursorFactory factory, int version, DatabaseErrorHandler errorHandler) {super (context, name, factory, version, errorHandler); // TODO Auto-generated constructor stub} @ Overridepublic void onCreate (SQLiteDatabase db) {// automatically create the table db.exe cSQL (CREATE_TABLE_ SQL) when using the data library for the first time; Log. I (create, OK) ;}@ Overridepublic void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub }}

MainActicity. java

 

 

Package sn. qdj. sqlitedemo; import java. util. arrayList; import java. util. hashMap; import java. util. map; import android. app. activity; import android. content. intent; import android. database. cursor; import android. database. sqlite. SQLiteDatabase; import android. OS. bundle; import android. util. log; import android. view. view; import android. view. view. onClickListener; import android. widget. button; import android. widget. E DitText; import android. widget. toast; public class MainActivity extends Activity {MySQLite dbHelpher; Button insert = null; Button search = null; @ Override protected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main);/*** create a MySQLite object and specify the database version as 1 */dbHelpher = new MySQLite (this, myDict. db3, null, 1); insert = (Button) findViewById (R. id. Btn_insert); search = (Button) findViewById (R. id. btn_search);/***** insert event */insert. setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View v) {// TODO Auto-generated method stubLog. I (insert, front); String word = (EditText) findViewById (R. id. et_word )). getText (). toString (); String detail = (EditText) findViewById (R. id. et_detail )). getText (). toString (); // insert statement myInsert (dbHelpher. getRea DableDatabase (), word, detail); Log. I (insert, after); Toast. makeText (getApplicationContext (), inserted successfully, 800 ). show () ;}});/*** query event */search. setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View v) {// TODO Auto-generated method stubString key = (EditText) findViewById (R. id. et_word )). getText (). toString (); String SQL = SELECT * FROM dict WHERE word LIKE? OR detail LIKE ?; String selectionArgs [] = {% + key + %, % + key + %}; Cursor cursor = dbHelpher. getReadableDatabase (). rawQuery (SQL, selectionArgs); // create a Bundle object Bundle data = new Bundle (); data. putSerializable (data, converCursorToList (cursor); // create an IntentIntent intent = new Intent (MainActivity. this, ResultActivity. class); intent. putExtras (data); // start ActivitystartActivity (intent) ;}});} protected ArrayList
 
  
> ConverCursorToList (Cursor cursor) {ArrayList
  
   
> Result = new ArrayList
   
    
> (); // Traverse the result set while (cursor. moveToNext () {Map
    
     
Map = new HashMap
     
      
(); Map. put (word, cursor. getString (1); map. put (detail, cursor. getString (2); result. add (map);} return result;}/***** @ param db * @ param word * @ param detail description */private void myInsert (SQLiteDatabase db, String word, string detail) {db.exe cSQL (insert into dict values (null ,?,?), New String [] {word, detail}) ;}@ Override public void onDestroy () {super. onDestroy ();/*** close SQLiteDatabase */if (dbHelpher! = Null) {dbHelpher. close ();}}}
     
    
   
  
 

Activity_main.xml

 

 

ResultActivity. java

 

 

Package sn. qdj. sqlitedemo; import java. util. list; import java. util. map; import android. app. activity; import android. content. intent; import android. OS. bundle; import android. widget. listView; import android. widget. simpleAdapter; public class ResultActivity extends Activity {@ Override protected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. result); ListView listView = (ListView) findViewById (R. id. show); Intent intent = getIntent (); // gets the data Bundle data = intent. getExtras (); // retrieve the data List from the Bundle
 
  
> List = (List
  
   
>) Data. getSerializable (data); // encapsulate the List into SimpleAdapter adapter = new SimpleAdapter (ResultActivity. this, list, R. layout. line, new String [] {word, detail}, new int [] {R. id. word, R. id. detail}); // fill the ListView. setAdapter (adapter );}}
  
 

Result. xml