Android-query all, Query Count, query page

1. persondao

The full persondao code is as follows:

package com.njupt.sqllist;import java.util.ArrayList;import java.util.List;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;public class PersonDao {DBOpenHelper helper ;public PersonDao(Context context){helper = new DBOpenHelper(context);}public void insert(Person p){SQLiteDatabase db = helper.getWritableDatabase();db.execSQL("insert into person(name,balance) values(?,?)", new Object[]{ p.getName(),p.getBalance()});    db.close();}public void delete(int id){SQLiteDatabase db = helper.getWritableDatabase();db.execSQL("delete from person where id = ?", new Object[]{id});db.close();}public void update(Person p){SQLiteDatabase db = helper.getWritableDatabase();db.execSQL("update person set name = ? , balance = ? where id = ? ", new Object[]{p.getName(),p.getBalance(),p.getId()});}public Person query(int id){SQLiteDatabase db = helper.getReadableDatabase();Cursor c = db.rawQuery("select name , balance from person where id = ?", new String[]{id + ""});    Person p = null ;if(c.moveToNext()){String name = c.getString(c.getColumnIndex("name"));int balance = c.getInt(1);p = new Person(id,name,balance);}return p;}public List<Person> queryAll(){SQLiteDatabase db = helper.getReadableDatabase();Cursor c = db.rawQuery("select * from person", null);List<Person> persons = new ArrayList<Person>();while(c.moveToNext()){Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));persons.add(p);}return persons;}public int queryCount(){SQLiteDatabase db = helper.getReadableDatabase();Cursor c = db.rawQuery("select count(*) from person", null); c.moveToNext();  int count = c.getInt(0); return count;}public List<Person> queryPage(int pageNum , int pageSize){SQLiteDatabase db = helper.getReadableDatabase();Cursor c = db.rawQuery("select * from person limit ?,?", new String[]{(pageNum - 1)*pageSize + "",pageSize + ""  });List<Person> persons = new ArrayList<Person>();while(c.moveToNext()){Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));persons.add(p);}return persons;}}

2. dbtest

The full test code is attached below:

Package COM. njupt. sqllist; import Java. util. list; import Java. util. random; import android. test. androidtestcase; public class dbtest extends androidtestcase {public void test1 () {dbopenhelper helper = new dbopenhelper (getcontext (); helper. getwritabledatabase ();} public void testinsert () {persondao Dao = new persondao (getcontext (); random r = new random (40000); For (INT I = 0; I <100; ++ I) {person P = new person (0, "test" + I, R. nextint (); Dao. insert (p) ;}} public void testdelete () {persondao Dao = new persondao (getcontext (); Dao. delete (1);} public void testupdate () {persondao Dao = new persondao (getcontext (); person P = new person (2, "Liu Yifei", 45000); Dao. update (p);} public void testquery () {persondao Dao = new persondao (getcontext (); person P = Dao. query (3); system. out. println (p);} public void testqueryall () {persondao Dao = new persondao (getcontext (); List <person> Persons = Dao. queryall (); For (person P: Persons) {system. out. println (p) ;}} public void testquerycount () {persondao Dao = new persondao (getcontext (); int COUNT = Dao. querycount (); system. out. println (count);} public void testquerypage () {persondao Dao = new persondao (getcontext (); List <person> Persons = Dao. querypage (2, 10); For (person P: Persons) {system. out. println (p );}}}

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The paging result is as follows:

Total number of queries: