Layout

用RecyclerView顯示資料

<TextView
    android:text="TextView"
    android:textColor="#000000" android:textSize="20sp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" android:id="@+id/tv_name" android:layout_weight="1"/>
<TextView
    android:text="TextView"
    android:textColor="#000000" android:textSize="20sp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" android:id="@+id/tv_ways" android:layout_weight="1"/>
<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" app:srcCompat="@android:drawable/ic_menu_edit"
    android:id="@+id/imageView" android:layout_weight="1"/>

因為文字非常多，所以在RecyclerView的Layout中只放入兩個TextView，和一個ImageView當作修改的按鈕

Method

建立資料庫物件和Adapter物件及一個ArrayList當作資料來源

private val item = ArrayList<Notes>()
private lateinit var db : SQLiteDatabase
private lateinit var adapter : MyAdapter

在Adapter中，對三個元件監聽，當兩個TextView被按下時，彈出一個對話框顯示詳細的內容

class MyAdapter (private val context: Context,private val data: ArrayList<Notes>): RecyclerView.Adapter<MyAdapter.ViewHolder>() {
    class ViewHolder(v: View): RecyclerView.ViewHolder(v) {
        val tv_name = v.findViewById<TextView>(R.id.tv_name)
        val tv_ways = v.findViewById<TextView>(R.id.tv_ways)
    }

    override fun onCreateViewHolder(viewGroup: ViewGroup, position: Int): ViewHolder {
        val v = LayoutInflater.from(viewGroup.context).inflate(R.layout.item,viewGroup,false)
        return ViewHolder(v)
    }

    override fun getItemCount() = data.size

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        var dialog = AlertDialog.Builder(context)
            .setTitle(data[position].name)
            .setMessage("沖煮方式:${data[position].ways}\n" +
                    "酸:${data[position].acidity} 苦:${data[position].bitter} 甜:${data[position].sweet}\n" +
                    "風味描述:\n" + "${data[position].flavor}")
            .setPositiveButton("確認"){dialog,i->}
        
        holder.tv_name.text = data[position].name
        holder.tv_ways.text = data[position].ways
        holder.tv_name.setOnClickListener { 
            dialog.show()
        }
        holder.tv_ways.setOnClickListener {
            dialog.show() 
        }
    }
}

在MainActivity中，利用SQL指令取得資料庫的資料

fun viewUpdate() {
    db = DBHelper(this).writableDatabase
    //從資料庫取得資料
    val notes = db.rawQuery("SELECT * FROM Notes", null)
    //移動到第一筆資料
    notes.moveToFirst()
    item.clear()
    for (i in 0 until notes.count) {
        item.add(
            Notes(
                notes.getLong(0), notes.getString(1), notes.getInt(2), notes.getInt(3),
                notes.getInt(4), notes.getString(5), notes.getString(6))
        )
        //移動到下一筆資料
        notes.moveToNext()
        //更新RecyclerView
        adapter.notifyDataSetChanged()
    }
}

Activity回傳資料

startActivityForResult()
使用startActivityForResult()，可以讓被啟動的Activity回傳資料到onActivityResult()，啟動時設定requestCode判斷被啟動的是哪個Activity，在被啟動的Activity設定resultCode判斷資料處理情形

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    btn_add.setOnClickListener {
        val i = Intent(this,EditActivity::class.java)
        startActivityForResult(i,1)//將requestCode設為1 啟動EditActivity
    }
}
//當EditActivity結束時啟動
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    
    data?.extras.let {
        //當EditActivity有存資料到資料庫時執行
        if(requestCode == 1 && resultCode == Activity.RESULT_OK){
            viewUpdate()
        }
    }
    
}

在EditActivity加入setResult(Activity.RESULT_OK)設置ResultCode

btn_add.setOnClickListener {
    val db = DBHelper(this).writableDatabase
    val Id = System.currentTimeMillis()
    //儲存資料
    db.execSQL("INSERT INTO Notes(id,name,acidity,bitter,sweet,ways,flavor) VALUES(?,?,?,?,?,?,?)",
                arrayOf<Any?>(Id,"${ed_name.text}",seekBar_acidity.progress,seekBar_bitter.progress,seekBar_sweet.progress,"${ed_name.text}","${ed_flavor.text}")
    )
    //將ResultCode設為 RESULT_OK
    setResult(Activity.RESULT_OK)
    finish()
}

實作成果