ch14.rar

package com.ehappy.exsqlite04; import androidx.appcompat.app.AlertDialog; import androidx.appcompat.app.AppCompatActivity; import androidx.cursoradapter.widget.SimpleCursorAdapter; import android.content.DialogInterface; import android.database.Cursor; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.Toast; public class MainActivity extends AppCompatActivity { /* 自建的資料庫類別 */ private MyDB db=null; /* 資料表欄位 */ //private final static String _ID = "_id"; //private final static String NAME = "name"; //private final static String PRICE = "price"; Button btnAppend,btnEdit,btnDelete,btnClear; EditText edtName,edtPrice; ListView listview01; Cursor cursor; long myid; // 儲存 _id 的值 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // 取 得元件 edtName=(EditText)findViewById(R.id.edtName); edtPrice=(EditText)findViewById(R.id.edtPrice); listview01=(ListView)findViewById(R.id.ListView01); btnAppend=(Button)findViewById(R.id.btnAppend); btnEdit=(Button)findViewById(R.id.btnEdit); btnDelete=(Button)findViewById(R.id.btnDelete); btnClear=(Button)findViewById(R.id.btnClear); // 設定偵聽 btnAppend.setOnClickListener(myListener); btnEdit.setOnClickListener(myListener); btnDelete.setOnClickListener(myListener); btnClear.setOnClickListener(myListener); listview01.setOnItemClickListener(listview01Listener); db =new MyDB(this); // 建立 MyDB 物件 db.open(); cursor=db.getAll();// 載入全部資料 UpdateAdapter(cursor); // 載入資料表至 ListView 中 } private ListView.OnItemClickListener listview01Listener= new ListView.OnItemClickListener(){ public void onItemClick(AdapterView<?> parent, View v, int position, long id) { ShowData(id); cursor.moveToPosition(position); } }; private void ShowData(long id){ //顯示單筆資料 Cursor c=db.get(id); myid=id; // 取得 _id 欄位 edtName.setText(c.getString(1)); // name 欄位 edtPrice.setText("" + c.getInt(2)); // price 欄位 } @Override protected void onDestroy(){ super.onDestroy(); db.close(); // 關閉資料庫 } private Button.OnClickListener myListener=new Button.OnClickListener(){ public void onClick(View v){ try{ switch (v.getId()){ case R.id.btnAppend:{ // 新增 int price=Integer.parseInt(edtPrice.getText().toString()); String name=edtName.getText().toString(); if ( db.append(name,price)>0){ cursor=db.getAll();// 載入全部資料 UpdateAdapter(cursor); // 載入資料表至 ListView 中 ClearEdit(); } break; }case R.id.btnEdit: { //修改 int price=Integer.parseInt(edtPrice.getText().toString()); String name=edtName.getText().toString(); if (db.update(myid,name,price)){ cursor=db.getAll();// 載入全部資料 UpdateAdapter(cursor); // 載入資料表至 ListView 中 } break; }case R.id.btnDelete: { //刪除 if (cursor != null && cursor.getCount() >= 0){ AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this); builder.setTitle("確定刪除"); builder.setMessage("確定要刪除" + edtName.getText() + "這筆資料?"); builder.setNegativeButton("取消", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int i) { } }); builder.setPositiveButton("確定",new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int i) { if (db.delete(myid)){ cursor=db.getAll();// 載入全部資料 UpdateAdapter(cursor); // 載入資料表至 ListView 中 ClearEdit(); } } }); builder.show(); } break; }case R.id.btnClear: { //清除 ClearEdit(); break; } } }catch (Exception err){ Toast.makeText(getApplicationContext(), "資料不正確!", Toast.LENGTH_SHORT).show(); } } }; public void ClearEdit(){ edtName.setText(""); edtPrice.setText(""); } public void UpdateAdapter(Cursor cursor){ if (cursor != null && cursor.getCount() >= 0){ SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2, // 包含兩個資料項 cursor, // 資料庫的 Cursors 物件 new String[] { "name", "price" }, // name、price 欄位 new int[] { android.R.id.text1, android.R.id.text2 }, 0); listview01.setAdapter(adapter); // 將adapter增加到listview01中 } } }