SQLite练习项目——联系人列表增删改查

package com.example.xx.myapplication.ui; import android.content.DialogInterface; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.os.Bundle; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.view.ContextMenu; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.Button; import android.widget.ListView; import android.widget.SimpleCursorAdapter; import android.widget.Toast; import com.example.xx.myapplication.PersonAdapter; import com.example.xx.myapplication.R; import com.example.xx.myapplication.dal.PersonDao; import com.example.xx.myapplication.entity.Person; import java.util.List; public class MainActivity extends AppCompatActivity implements View.OnClickListener,DialogInterface.OnClickListener{ private Button btn_add; private ListView lv_contacts; private List<Person> persons; private PersonAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); btn_add = findViewById(R.id.btn_add); lv_contacts = findViewById(R.id.lv_contacts); btn_add.setOnClickListener(this); //获取数据源 PersonDao personDao = new PersonDao(this); persons = personDao.query(null, null, "_name ASC"); adapter = new PersonAdapter(this,persons); lv_contacts.setAdapter(adapter); //为listview注册ContextMenu registerForContextMenu(lv_contacts); } public static final int MENU_ITEM_EDIT = 1; public static final int MENU_ITEM_DELETE = 2; private int actionPosition; @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) { //将参数转换为AdapterView.AdapterContextMenuInfo类型 AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) menuInfo; actionPosition = info.position; menu.add(Menu.NONE,MENU_ITEM_EDIT,Menu.NONE,"编辑"+persons.get(actionPosition).getName()+"的个人信息"); menu.add(Menu.NONE,MENU_ITEM_DELETE,Menu.NONE,"删除"+persons.get(actionPosition).getName()+"的个人信息"); super.onCreateContextMenu(menu, v, menuInfo); } @Override public boolean onContextItemSelected(MenuItem item) { switch (item.getItemId()){ case MENU_ITEM_EDIT: //打开新的Activity Intent intent = new Intent(this,ContactFormActivity.class); intent.putExtra("person",persons.get(actionPosition)); startActivity(intent); break; case MENU_ITEM_DELETE: //弹出确认对话框 AlertDialog.Builder builder = new AlertDialog.Builder(this); AlertDialog dialog = builder.setTitle("警告") .setMessage("删除操作不可恢复，确定删除吗？") .setPositiveButton("确定",this) .setNegativeButton("取消",null) .create(); dialog.show(); break; } return super.onContextItemSelected(item); } @Override public void onClick(View view) { Intent intent = new Intent(this,ContactFormActivity.class); startActivity(intent); } @Override protected void onRestart() { super.onRestart(); //获取新的数据，刷新列表 PersonDao personDao = new PersonDao(this); persons.clear(); persons.addAll(personDao.query(null, null, "_name ASC")); adapter.notifyDataSetChanged(); } @Override public void onClick(DialogInterface dialogInterface, int i) { //删除 PersonDao personDao = new PersonDao(this); int affectedRows = personDao.delete(persons.get(actionPosition).getId()); if(affectedRows > 0){ Toast.makeText(this,"删除成功",Toast.LENGTH_SHORT).show(); //获取新数据,刷新页面 persons.clear(); persons.addAll(personDao.query(null, null, "_name ASC")); adapter.notifyDataSetChanged(); }else { Toast.makeText(this,"删除失败，请联系管理员",Toast.LENGTH_SHORT).show(); } } }