Write a diary using SQLite in android Development

Write a diary using SQLite in android Development

Use a database to store data.

The following is a small example.

The effect is as follows:

When no data is displayed in the LIstView, we need to tell the user that there is no data.

There are two methods:

1.

The activity inherits the ListActivity and is written in the layout file as follows:

2.

If (adapter. isEmpty () & textView = null) {textView = new TextView (MainActivity. this); textView. setText ("the host is very lazy and nothing is left"); textView. setVisibility (View. GONE); (ViewGroup) listView. getParent ()). addView (textView); listView. setEmptyView (textView);} else {listView. setAdapter (simpleCursorAdapter );}

Database usage (Android comes with SQLite. If you want to use other databases, you must use Web Server ):

Inherit from SQLiteOpenHelper.

Public DBHelper (Context context) // Database Name, database version public void onCreate (SQLiteDatabase db) /// create public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) // update the database

The Code is as follows:

Cn.edu. bzu. diary. activity

MainActivity. java

Public class MainActivity extends Activity {ListView listView; Cursor diaries; // Cursor TextView textView = null; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); listView = (ListView) findViewById (R. id. listview); refreshList (); this. registerForContextMenu (listView);}/*** refresh Adapter */public void refreshList () {DiaryDao diaryDao = new DiaryDao (this); diaries = diaryDao. getAllDairies (); SimpleCursorAdapter simpleCursorAdapter = new SimpleCursorAdapter (MainActivity. this, R. layout. item, diaries, new String [] {"title", "created"}, new int [] {R. id. title, R. id. created}); if (simpleCursorAdapter. isEmpty () & textView = null) {textView = new TextView (MainActivity. this); textView. setText ("the host is very lazy and nothing is left"); textView. setVisibility (View. GONE); (ViewGroup) listView. getParent ()). addView (textView); listView. setEmptyView (textView);} else {listView. setAdapter (simpleCursorAdapter) ;}}@ Overridepublic void onCreateContextMenu (ContextMenu menu, View v, ContextMenuInfo menuInfo) {menu. setHeaderTitle ("operation"); menu. add (0, 1, Menu. NONE, "edit"); menu. add (0, 2, Menu. NONE, "delete"); super. onCreateContextMenu (menu, v, menuInfo) ;}@ Overridepublic boolean onContextItemSelected (MenuItem item) {// onContextItemSelectedAdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo) item. getMenuInfo (); switch (item. getItemId () {case 1: Intent intent = new Intent (); Bundle bundle = new Bundle (); bundle. putInt ("id", (int) menuInfo. id); intent. putExtras (bundle); intent. setClass (MainActivity. this, diaryeditaciti.pdf. class); startActivity (intent); break; case 2: DiaryDao dao = new DiaryDao (MainActivity. this); dao. delete (int) menuInfo. id); // menuInfo. the id is consistent with the database ID refreshList (); break;} return super. onContextItemSelected (item);}/*** refresh the Adapter by using the lifecycle in the exit log adding process */@ Overrideprotected void onResume () {super. onResume (); refreshList () ;}@ Overridepublic boolean onCreateOptionsMenu (Menu menu) {getMenuInflater (). inflate (R. menu. main, menu); return true;}/*** enter the "Diary add page" through the menu */@ Overridepublic boolean onOptionsItemSelected (MenuItem item) {switch (item. getItemId () {case R. id. save: Intent intent = new Intent (); intent. setClass (MainActivity. this, diaryaddaciti.pdf. class); startActivity (intent); break;} return super. onOptionsItemSelected (item );}}

Diaryaddaciti.pdf. java

Public class diaryaddaciti#extends Activity {DiaryDao diaryDao = new DiaryDao (diaryaddaciti.pdf. this); Button button; EditText editText, editText2; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. diaryadd_aciti.pdf); editText = (EditText) findViewById (R. id. et_diaryadd); // The title editText2 = (EditText) findViewById (R. id. et02_diaryadd); // content button = (Button) findViewById (R. id. but) ;}@ Overridepublic boolean onCreateOptionsMenu (Menu menu) {// Inflate the menu; this adds items to the action bar if it is present. getMenuInflater (). inflate (R. menu. diary_add_acitivity, menu); return true;} public void click (View view) {String title = editText. getText (). toString (); String content = editText2.getText (). toString (); Diary diary = new Diary (title, content, Tool. dateChange (new Date (); DiaryDao diaryDao = new DiaryDao (this); diaryDao. save (diary); finish ();}}

Diaryeditaciti.pdf. java

Public class DiaryEditAcitivity extends Activity {DiaryDao diaryDao = new DiaryDao (diaryeditaciti.pdf. this); Button button; EditText editText, editText2; int id; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. diaryadd_aciti.pdf); editText = (EditText) findViewById (R. id. et_diaryadd); // The title editText2 = (EditText) findViewById (R. id. et02 _ Diaryadd); // content button = (Button) findViewById (R. id. but); Bundle bundle = this. getIntent (). getExtras (); if (bundle! = Null) {id = bundle. getInt ("id"); Diary diary = diaryDao. getDiaryById (id); editText. setText (diary. getTitle (); editText2.setText (diary. getContent () ;}@ Overridepublic boolean onCreateOptionsMenu (Menu menu) {// Inflate the menu; this adds items to the action bar if it is present. getMenuInflater (). inflate (R. menu. diary_add_acitivity, menu); return true;} public void click (View view) {String title = editText. getText (). toString (); String content = editText2.getText (). toString (); Diary diary = new Diary (title, content, Tool. dateChange (new Date (); diary. setId (id); DiaryDao diaryDao = new DiaryDao (this); diaryDao. update (diary); finish ();}}

Cn.edu. bzu. diary. daoDiaryDao. java

Public class DiaryDao {private DBHelper dbHelper; private SQLiteDatabase sqLiteDatabase; public DiaryDao (Context context) {dbHelper = new DBHelper (context );} /*** Add a diary * @ param Diary */public void save (diary) {String SQL = "insert into diary (title, content, created) values (?,?,?) "; SqLiteDatabase = dbhelper.getwritabledatabase(;;sqlitedatabase.exe cSQL (SQL, new String [] {diary. getTitle (), diary. getContent (), diary. getDatetime ()});}/*** delete the id of the diary ** @ param id */public void delete (Integer id) {sqLiteDatabase = dbHelper. getWritableDatabase (); // The result is that sqlitedatabase.exe cSQL ("delete from diary where _ id =? ", New Object [] {id});}/*** update diary ** @ param Diary */public void update (diary) {sqLiteDatabase = dbHelper. getWritableDatabase (); // The result is that sqlitedatabase.exe cSQL ("update diary set title = ?, Content = ?, Created =? Where _ id =? ", New Object [] {diary. getTitle (), diary. getContent (), diary. getDatetime (), diary. getId ()});}/*** returns a cursor. You can also use the comments section to return a List set (using SimpleAdapter), where the cursor is used, the main reason is that * The ID in AdapterContextMenuInfo is consistent with that in the database * @ return cursor */public Cursor getAllDairies () {// Diary diary = null; // List
 
  
Diaries = new ArrayList
  
   
(); SqLiteDatabase = dbHelper. getReadableDatabase (); Cursor cursor = sqLiteDatabase. rawQuery ("select * from diary", null);/** while (cursor. moveToNext () {String title = * cursor. getString (cursor. getColumnIndex ("title"); String content = * cursor. getString (cursor. getColumnIndex ("content"); String created = * cursor. getString (cursor. getColumnIndex ("created"); diary = new * Diary (title, content, cr Eated); diaries. add (diary);} */return cursor;}/*** obtain the total number of records */public long count () {long count = 0; sqLiteDatabase = dbHelper. getReadableDatabase (); Cursor cursor = sqLiteDatabase. rawQuery ("select count (*) from diary", null); cursor. moveToFirst (); count = cursor. getLong (0); return count;} public Diary getDiaryById (int id) {sqLiteDatabase = dbHelper. getWritableDatabase (); Diary diary = null; Cursor cursor = SqLiteDatabase. rawQuery ("select * from diary where _ id =? ", New String [] {id +" "}); if (cursor. moveToFirst () {String title = cursor. getString (cursor. getColumnIndex ("title"); String content = cursor. getString (cursor. getColumnIndex ("content"); String created = cursor. getString (cursor. getColumnIndex ("created"); diary = new Diary (title, content, created);} return diary ;}}
  
 

Cn.edu. bzu. diary. dbDBHelper. java

Public class DBHelper extends SQLiteOpenHelper {public static final String DATABASE_NAME = "diary. db "; public static final int VERSION = 1; // Database Name, database VERSION public DBHelper (Context context) {super (context, DATABASE_NAME, null, VERSION ); // TODO Auto-generated constructor stub} // create a database, field: id (Primary Key), title, content, created; @ Overridepublic void onCreate (SQLiteDatabase db) {// TODO Auto-generated method stubdb.exe cSQL ("create table diary (_ id integer primary key autoincrement, title varchar (20), content varchar (1000), created) ") ;}// used for database updates @ Overridepublic void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub }}

Cn.edu. bzu. diary. entityDiary. java

public class Diary {private Integer id;private String title;private String content;private String datetime;public Diary(){}public Diary(String title,String content,String datetime){this.title = title;this.content = content;this.datetime = datetime;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public String getContent() {return content;}public void setContent(String content) {this.content = content;}public String getDatetime() {return datetime;}public void setDatetime(String datetime) {this.datetime = datetime;}@Overridepublic String toString() {return "Diary [title=" + title + ", content=" + content + ", datetime="+ datetime + "]";}}

Cn.edu. bzu. diary. toolsTool. java

Public class Tool {/*** time display style * @ param date * @ return */public static String dateChange (Date date) {SimpleDateFormat simpleDateFormat = new SimpleDateFormat ("MM dd, yyyy, hh: mm: ss seconds"); return simpleDateFormat. format (date );}}

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