半期考试 之 SQLite 操作2
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半期考试 之 SQLite 操作2
要求:
- 两个输入框,要求输入姓名和年龄;
- 下方四个按钮,分别表示增加,删除,更新,回滚;
- 添加或者删除后,下方的listview数据动态改变;
xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="@+id/editText_name"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:ems="10"
android:hint="Input name?"
android:inputType="textPersonName"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/editText_age"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="11dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:ems="10"
android:hint="Input age?"
android:inputType="number"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/editText_name" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="44dp"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:onClick="add"
android:text="Add"
app:layout_constraintEnd_toStartOf="@+id/button2"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="@+id/editText_age"
tools:ignore="OnClick" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="6dp"
android:layout_marginRight="6dp"
android:onClick="delete"
android:text="Delete"
app:layout_constraintBottom_toTopOf="@+id/listView"
app:layout_constraintEnd_toStartOf="@+id/button3"
app:layout_constraintStart_toEndOf="@+id/button"
tools:ignore="OnClick" />
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="2dp"
android:layout_marginRight="2dp"
android:onClick="update"
android:text="Update"
app:layout_constraintBottom_toTopOf="@+id/listView"
app:layout_constraintEnd_toStartOf="@+id/button4"
app:layout_constraintStart_toEndOf="@+id/button2"
tools:ignore="OnClick" />
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="1dp"
android:layout_marginRight="1dp"
android:onClick="retrieve"
android:text="Retrieve"
app:layout_constraintBottom_toTopOf="@+id/listView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/button3"
tools:ignore="OnClick" />
<ListView
android:id="@+id/listView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/button" />
</androidx.constraintlayout.widget.ConstraintLayout>
java
public class MainActivity extends AppCompatActivity
mysqlHelper mySQLHelper;
SQLiteDatabase db;
EditText editText_name, editText_age;
ListView listView;
SimpleCursorAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText_name = findViewById(R.id.editText_name);
editText_age = findViewById(R.id.editText_age);
listView = findViewById(R.id.listView);
mySQLHelper = new MySqlHelper(this, "db", null, 1);
db = mySQLHelper.getWritableDatabase();
Cursor cursor = db.query(MySqlHelper.PersonTable, null, null, null, null, null, null, null);
adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2, cursor, new String[]"name", "age", new int[]android.R.id.text1, android.R.id.text2, CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
listView.setAdapter(adapter);
public void add(View view)
String name = editText_name.getText().toString();
String age = editText_age.getText().toString();
// db.execSQL("insert into person(name,age) values('"+name+"','"+age+"')");
ContentValues contentValues = new ContentValues();
contentValues.put("name", name);
contentValues.put("age", age);
db.insert(MySqlHelper.PersonTable, null, contentValues);
reload();
public void delete(View view)
String name = editText_name.getText().toString();
db.delete(MySqlHelper.PersonTable, "name=?", new String[]name);
reload();
public void update(View view)
String name = editText_name.getText().toString();
String age = editText_age.getText().toString();
ContentValues contentValues = new ContentValues();
contentValues.put("name", name);
contentValues.put("age", age);
db.update(MySqlHelper.PersonTable, contentValues, "name=?", new String[]name);
reload();
public void retrieve(View view)
String name = editText_name.getText().toString();
new MyAsyncTask().execute("%" + name + "%");
// Cursor cursor=db.query(MySQLHelper.PersonTable,null,"name like *",new String[]name,null,null,null,null);
// adapter.swapCursor(cursor);
private void reload()
Cursor cursor = db.query(MySqlHelper.PersonTable, null, null, null, null, null, null, null);
adapter.swapCursor(cursor);
class MyAsyncTask extends AsyncTask<String, Nullable, Cursor>
@Override
protected Cursor doInBackground(String... strings)
Cursor cursor = db.query(MySqlHelper.PersonTable, null, "name like ?", new String[]"%" + strings[0] + "%", null, null, null, null);
return cursor;
@Override
protected void onPostExecute(Cursor cursor)
super.onPostExecute(cursor);
adapter.swapCursor(cursor);
数据库操作类
public class MySqlHelper extends SQLiteOpenHelper
public static final String PersonTable = "person";
public MySqlHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version)
super(context, name, factory, version);
@Override
public void onCreate(SQLiteDatabase db)
db.execSQL("create table if not exists person(_id integer primary key autoincrement,name text,age integer)");
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
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