Android-SQLite (add, delete, modify, query) operation instance code

Five classes are required:

1. entity class: Person. java

2. abstract class: SQLOperate. java (encapsulates Database Operations)

3. helper class: DBOpenHelper. java (inherits SQLiteOpenHelper)

4. Implementation class: SQLOperateImpl. java (implement abstract class SQLOperate. java)

5. Test class: Test. java (inheriting AndroidTestCase)

1. Person. java

Copy codeThe Code is as follows: package com. mrzhu. sqltite;

Public class Person {

Private int _ id;
Private String name;

Public int getId (){
Return _ id;
}

Public void setId (int _ id ){
This. _ id = _ id;
}

Public String getName (){
Return name;
}

Public void setName (String name ){
This. name = name;
}

@ Override
Public String toString (){
Return "Person [id =" + _ id + ", name =" + name + "]";
}

Public Person (){
Super ();
}

Public Person (int _ id, String name ){
Super ();
This. _ id = _ id;
This. name = name;
}
}

2. SQLOperate. java

Copy codeThe Code is as follows: package com. mrzhu. sqltite;

Import java. util. List;

/**
* Add, delete, modify, and query
* @ Author ZLQ
*
*/
Public interface SQLOperate {
Public void add (Person p );
Public void delete (int id );
Public void updata (Person p );
Public List <Person> find ();
Public Person findById (int id );
}

3. DBOpenHelper. java

Copy codeThe Code is as follows: package com. mrzhu. sqltite;

Import android. content. Context;
Import android. database. sqlite. SQLiteDatabase;
Import android. database. sqlite. SQLiteOpenHelper;

/**
* Helper class
* @ Author ZLQ
*
*/
Public class DBOpneHelper extends SQLiteOpenHelper {

Private static final int VERSION = 1; // VERSION
Private static final String DB_NAME = "people. db"; // Database Name
Public static final String STUDENT_TABLE = "student"; // table name
Public static final String _ ID = "_ id"; // name of the column in the table
Public static final String NAME = "name"; // NAME of the column in the table
// Create a database statement, and add spaces before and after STUDENT_TABLE, _ ID, and NAME.
Private static final String CREATE_TABLE = "create table" + STUDENT_TABLE + "(" + _ ID + "Integer primary key autoincrement," + NAME + "text )";

Public DBOpneHelper (Context context ){
Super (context, DB_NAME, null, VERSION );
}

// Called when the database is created for the first time
@ Override
Public void onCreate (SQLiteDatabase db ){
Db.exe cSQL (CREATE_TABLE );
}

// Called during Version Upgrade
@ Override
Public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion ){

}

}

4. SQLOperateImpl. java

Copy codeThe Code is as follows: package com. mrzhu. sqltite;

Import java. util. ArrayList;
Import java. util. List;

Import android. content. ContentValues;
Import android. content. Context;
Import android. database. Cursor;
Import android. database. sqlite. SQLiteDatabase;

Public class SQLOperateImpl implements SQLOperate {

Private DBOpneHelper dbOpenHelper;

Public SQLOperateImpl (Context context ){
DbOpenHelper = new DBOpneHelper (context );
}

/**
* Add: Use insert to insert data to the database.
*/
Public void add (Person p ){
SQLiteDatabase db = dbOpenHelper. getWritableDatabase ();
ContentValues values = new ContentValues ();
Values. put (DBOpneHelper. _ ID, p. getId ());
Values. put (DBOpneHelper. NAME, p. getName ());
Db. insert (DBOpneHelper. STUDENT_TABLE, null, values );
}

/**
* Delete: delete data by id
*/
Public void delete (int id ){
SQLiteDatabase db = dbOpenHelper. getWritableDatabase ();
Db. delete (DBOpneHelper. STUDENT_TABLE, DBOpneHelper. _ ID + "=? ", New String [] {String. valueOf (id )});
}

/**
* Modify the data of the specified id.
*/
Public void updata (Person p ){
SQLiteDatabase db = dbOpenHelper. getWritableDatabase ();
ContentValues values = new ContentValues ();
Values. put (DBOpneHelper. _ ID, p. getId ());
Values. put (DBOpneHelper. NAME, p. getName ());
Db. update (DBOpneHelper. STUDENT_TABLE, values, DBOpneHelper. _ ID + "=? ", New String [] {String. valueOf (p. getId ())});
}

/**
* Query and query all the data in the table
*/
Public List <Person> find (){
List <Person> persons = null;
SQLiteDatabase db = dbOpenHelper. getReadableDatabase ();
Cursor cursor = db. query (DBOpneHelper. STUDENT_TABLE, null );
If (cursor! = Null ){
Persons = new ArrayList <Person> ();
While (cursor. moveToNext ()){
Person person = new Person ();
Int _ id = cursor. getInt (cursor. getColumnIndex (DBOpneHelper. _ ID ));
String name = cursor. getString (cursor. getColumnIndex (DBOpneHelper. NAME ));
Person. setId (_ id );
Person. setName (name );
Persons. add (person );
}
}
Return persons;
}

/**
* Query data of a specified id
*/
Public Person findById (int id ){
SQLiteDatabase db = dbOpenHelper. getReadableDatabase ();
Cursor cursor = db. query (DBOpneHelper. STUDENT_TABLE, null, DBOpneHelper. _ ID + "=? ", New String [] {String. valueOf (id)}, null );
Person person = null;
If (cursor! = Null & cursor. moveToFirst ()){
Person = new Person ();
Int _ id = cursor. getInt (cursor. getColumnIndex (DBOpneHelper. _ ID ));
String name = cursor. getString (cursor. getColumnIndex (DBOpneHelper. NAME ));
Person. setId (_ id );
Person. setName (name );
}
Return person;
}
}

5. Test. java

Add <application> </application> In AndroidManifest. xml

(TargetPackage is the package name of the current project)

<Instrumentation

Android: targetPackage = "com. mrzhu. sqltite"

Android: name = "android. test. InstrumentationTestRunner">

</Instrumentation>

In <application> </application>, add <uses-library android: name = "android. test. runner"/>

Copy codeThe Code is as follows: package com. mrzhu. sqltite;

Import java. util. List;

Import android. test. AndroidTestCase;
Import android. util. Log;

Public class Test extends AndroidTestCase {
Public void testAdd () throws Exception {
SQLOperateImpl test = new SQLOperateImpl (getContext ());
Person person = new Person (2, "Peter ");
Test. add (person );
}

Public void testDelete () throws Exception {
SQLOperateImpl test = new SQLOperateImpl (getContext ());
Test. delete (1 );
}

Public void testUpdata () throws Exception {
SQLOperateImpl test = new SQLOperateImpl (getContext ());
Person person = new Person (1, "Tom ");
Test. updata (person );
}

Public void testFind () throws Exception {
SQLOperateImpl test = new SQLOperateImpl (getContext ());
List <Person> persons = test. find ();
For (Person person: persons ){
Log. I ("System. out", person. toString ());
}
}

Public void testFindById () throws Exception {
SQLOperateImpl test = new SQLOperateImpl (getContext ());
Person person = test. findById (2 );
Log. I ("System. out", person. toString ());
}
}