เพิ่มข้อมูลได้ จากนั้นใช้คอมโบบ็อก โดยดึงข้อมูลมาจากฐานข้อมูล

activity_main.xml

[code lang=”xml”]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.phaisarn.jackapplication.MainActivity">

<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal">

<EditText android:id="@+id/edittext_newcategory" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:hint="New Category" />

<Button android:id="@+id/button_category" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Add" />

</LinearLayout>

<Spinner android:id="@+id/spinner_categories" android:layout_width="fill_parent" android:layout_height="wrap_content" />

</LinearLayout>
[/code]

MainActivity.java

[code lang=”java”]
package com.phaisarn.jackapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private DataBaseHelper db;
private Spinner spinnerCategories;
private EditText editTextNewCategory;
private Button buttonCategory;

private List<String> listCategories = new ArrayList<>();
private ArrayAdapter<String> adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

// connect database
db = new DataBaseHelper(this);
if (db == null)
db = new DataBaseHelper(this);

spinnerCategories = (Spinner) findViewById(R.id.spinner_categories);
editTextNewCategory = (EditText) findViewById(R.id.edittext_newcategory);
buttonCategory = (Button) findViewById(R.id.button_category);
buttonCategory.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String newCategory = editTextNewCategory.getText().toString();
if (newCategory .equalsIgnoreCase("")) {
Toast.makeText(getApplicationContext(), "Please Enter New Category", Toast.LENGTH_SHORT).show();
} else {
db.addCategory(new Category(newCategory ));
prepareData();
editTextNewCategory.setText("");
//Toast.makeText(MainActivity.this, "New Category was Successfully added to Database", Toast.LENGTH_SHORT).show();
}
}
});

prepareData();
}

public void prepareData() {
listCategories = db.getAllCategories();
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, android.R.id.text1, listCategories);
spinnerCategories.setAdapter(adapter);
}
}
[/code]

Category.java

[code lang=”java”]
package com.phaisarn.jackapplication;

/**
* Created by jack on 2/9/2017.
*/

public class Category {
int id;
String name;

public Category(String name) {
this.name = name;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}
[/code]

DataBaseHelper.java

[code lang=”java”]
package com.phaisarn.jackapplication;

/**
* Created by jack on 2/9/2017.
*/

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import java.util.ArrayList;
import java.util.List;

public class DataBaseHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "categories";
private static final String TABLE_NAME = "category";
private static final String COLUMN_ID = "id";
private static final String COLUMN_NAME = "name";

private static final String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "("
+ COLUMN_ID + " INTEGER PRIMARY KEY,"
+ COLUMN_NAME + " TEXT" + ")";
private static final String CREATE_UNIQUE_INDEX = "CREATE UNIQUE INDEX IF NOT EXISTS "
+ COLUMN_NAME + " ON "
+ TABLE_NAME + "(" + COLUMN_NAME + ")";

public DataBaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
db.execSQL(CREATE_UNIQUE_INDEX);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//Drop table if exists
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
//create the table again
onCreate(db);
}

public void addCategory(Category category) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(COLUMN_NAME, category.getName());
db.insert(TABLE_NAME, null, cv);
db.close();
}

public List<String> getAllCategories() {
List<String> list = new ArrayList<>();

SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT " + COLUMN_NAME + " FROM " + TABLE_NAME, null);
if (cursor.moveToFirst()) {
do {
list.add(cursor.getString(0));
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return list;
}
}
[/code]