我建議你引用SQLiteOpenHelper而不是硬編碼查詢。
下面的代碼將幫助您
員工模型類
package com.database;
public class Employee {
int _id;
String _name;
String _phone_number;
public Employee(){
}
// constructor
public Employee (int id, String name, String _phone_number){
this._id = id;
this._name = name;
this._phone_number = _phone_number;
}
// constructor
public Employee (String name, String _phone_number){
this._name = name;
this._phone_number = _phone_number;
}
// getting ID
public int getID(){
return this._id;
}
// setting id
public void setID(int id){
this._id = id;
}
// getting name
public String getName(){
return this._name;
}
// setting name
public void setName(String name){
this._name = name;
}
// getting phone number
public String getPhoneNumber(){
return this._phone_number;
}
// setting phone number
public void setPhoneNumber(String phone_number){
this._phone_number = phone_number;
}
}
SQLite的助手類
公共類DatabaseHelper擴展SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "employeeDB";
private static final String TABLE_EMPLOYEE = "employee";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_PH_NO = "phone_number";
public DatabaseHelper (Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_EMPLOYEE + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
+ KEY_PH_NO + " TEXT" + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
// Create tables again
onCreate(db);
}
個
CRUD操作
// 添加新員工
public void addEmployee(Employee employee) {}
// 獲得一個員工
public Contact getEmployee(int id) {}
// 讓所有員工
public List<Employee> getAllEmployees() {}
// 獲取僱員計數
public int getEmployeesCount() {}
// 更新單個僱員
public int updateEmployee(Employee employee) {}
// 刪除單個僱員
public void deleteEmployee(Employee employee) {}
插入新記錄
public void addemployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, employee.getName());
values.put(KEY_PH_NO, employee.getPhoneNumber());
db.insert(TABLE_EMPLOYEE, null, values);
db.close();
}
讀行（S）
public Contact getEmployee(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_EMPLOYEE, new String[] { KEY_ID,
KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Employee employee= new Employee(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), cursor.getString(2));
return employee;
}
讓所有員工
public List<Contact> getAllEmployees() {
List<Employee> employeeList = new ArrayList<Employee>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_EMPLOYEE;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Employee employee= new Employee();
employee.setID(Integer.parseInt(cursor.getString(0)));
employee.setName(cursor.getString(1));
employee.setPhoneNumber(cursor.getString(2));
employeeList.add(employee);
} while (cursor.moveToNext());
}
return employeeList;
}
讓所有員工數
public int getEmployeesCount() {
String countQuery = "SELECT * FROM " + TABLE_EMPLOYEE;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
// return count
return cursor.getCount();
}
更新記錄
public int updateEmployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, employee.getName());
values.put(KEY_PH_NO, employee.getPhoneNumber());
// updating row
return db.update(TABLE_EMPLOYEE, values, KEY_ID + " = ?",
new String[] { String.valueOf(employee.getID()) });
}
刪除記錄
public void deleteEmployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_EMPLOYEE, KEY_ID + " = ?",
new String[] { String.valueOf(employee.getID()) });
db.close();
}
你在模擬器嘗試？ – Lucifer
是的，我試圖在模擬器。 – Moyeen
所以當你檢查/ data/data /目錄時，你可能已經關閉了你的模擬器，我建議你讓模擬器打開然後檢查它。 – Lucifer