안드로이드 앱 개발 연습 - 8 | Storage

내부 저장소

FileUtil.kt

object FileUtil {
    fun readTextFile(fullPath: String): String {
        val file = File(fullPath)
        if (!file.exists()) return ""
        val reader = FileReader(file)
        val buffer = BufferedReader(reader)

        var temp = ""
        val result = StringBuffer()

        while (true) {
            temp = buffer.readLine()
            if (temp == null) break;
            else result.append(buffer)
        }

        buffer.close()
        return result.toString()
    }

    fun writeTextFile(directory: String, filename: String, data: String) {
        val dir = File(directory)
        if (!dir.exists()) dir.mkdirs()
        val writer = FileWriter("$directory/$filename")
        val buffer = BufferedWriter(writer)

        buffer.write(data)
        buffer.close()
    }
}

MainActivity.kt

class MainActivity : AppCompatActivity() {
    private val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.btnRead.setOnClickListener {
            var data = FileUtil.readTextFile("${filesDir}/data.txt")
            binding.textData.setText(data)
        }
        binding.btnWrite.setOnClickListener {
            var data = binding.textData.toString()
            FileUtil.writeTextFile("$filesDir", "data.txt", data)
        }
    }
}

---

SharedPreferences

MainActivity.kt

class MainActivity : AppCompatActivity() {
    private val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    private val shared by lazy { getSharedPreferences("data", Context.MODE_PRIVATE) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        initializeOption()

        val editor = shared.edit()

        binding.inputName.addTextChangedListener {
            val text = binding.inputName.text.toString()
            editor.putString("nickname", text)
            editor.apply()
        }
        binding.swt1.setOnCheckedChangeListener { buttonView, isChecked ->
            editor.putBoolean("option1", isChecked)
            editor.apply()
        }
        binding.swt2.setOnCheckedChangeListener { buttonView, isChecked ->
            editor.putBoolean("option2", isChecked)
            editor.apply()
        }
        binding.swt3.setOnCheckedChangeListener { buttonView, isChecked ->
            editor.putBoolean("option3", isChecked)
            editor.apply()
        }
        binding.radioGroup.setOnCheckedChangeListener { group, checkedId ->
            when (checkedId) {
                R.id.radioBtn1 -> {
                    editor.putInt("radioGroup", 0)
                    editor.apply()
                }
                R.id.radioBtn2 -> {
                    editor.putInt("radioGroup", 1)
                    editor.apply()
                }
            }
        }
        binding.checkBtn1.setOnCheckedChangeListener { buttonView, isChecked ->
            editor.putBoolean("myOption3", isChecked)
            editor.apply()
        }
        binding.checkBtn2.setOnCheckedChangeListener { buttonView, isChecked ->
            editor.putBoolean("myOption4", isChecked)
            editor.apply()
        }
    }

    private fun initializeOption() {
        binding.inputName.setText(shared.getString("nickname", ""))
        binding.swt1.isChecked = shared.getBoolean("option1", false)
        binding.swt2.isChecked = shared.getBoolean("option2", false)
        binding.swt3.isChecked = shared.getBoolean("option3", false)
        when (shared.getInt("radioGroup", 0)) {
            0 -> binding.radioBtn1.isChecked = true
            1 -> binding.radioBtn2.isChecked = true
        }
        binding.checkBtn1.isChecked = shared.getBoolean("myOption3", false)
        binding.checkBtn2.isChecked = shared.getBoolean("myOption4", false)
    }
}

 

SharedPreferences

private val shared by lazy { getSharedPreferences("name", Context.MODE_PRIVATE) }

 

Save Data

val editor = shared.edit()

editor.putString("nickname", text)
editor.apply()

Type	Code
Float	putFloat(key: String, value: Float)
Long	putLong(key: String, value: Long)
Int	putInt(key: String, value: Int)
String	putString(key: String, value: String)
Boolean	putBoolean(key: String, value: Boolean)
Set<String>	putStringSet(key: String, value: Set<String>)

 

Read Data

binding.inputName.setText(shared.getString("nickname", ""))

Type	Code
Float	getFloat(key: String, defaultValue: Float)
Long	getLong(key: String, defaultValue: Long)
Int	getInt(key: String, defaultValue: Int)
String	getString(key: String, defaultValue: String)
Boolean	getBoolean(key: String, defaultValue: Boolean)
Set<String>	getStringSet(key: String, defaultValue: Set<String>)

 

Other Method

Method	Description
remove(String Key)	해당 키의 데이터를 삭제
clear()	모든 데이터를 삭제
apply()	변경한 업데이트를 파일에 비동기적으로 저장
commit()	변경한 업데이트를 파일에 동기적으로 저장 (동기 작업이므로 UI 스레드에서 호출하는 것을 피해야 함)

activity_main.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">

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="20dp"
        android:orientation="vertical"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:orientation="horizontal">

            <EditText
                android:id="@+id/inputName"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:ems="10"
                android:hint="Input your Nickname"
                android:inputType="textPersonName"
                android:minHeight="48dp" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="150dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/textView2"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:text="Setting Option" />

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <Switch
                    android:id="@+id/swt1"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="Option1" />

                <Switch
                    android:id="@+id/swt2"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="Option2" />

                <Switch
                    android:id="@+id/swt3"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="Option3" />
            </LinearLayout>

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/textView3"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:text="Setting Option2" />

            <RadioGroup
                android:id="@+id/radioGroup"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1">

                <RadioButton
                    android:id="@+id/radioBtn1"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="My Option1" />

                <RadioButton
                    android:id="@+id/radioBtn2"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="My Option2" />
            </RadioGroup>
        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/textView4"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:text="Setting Option3" />

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <CheckBox
                    android:id="@+id/checkBtn1"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="My Option3" />

                <CheckBox
                    android:id="@+id/checkBtn2"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="My Option4" />
            </LinearLayout>
        </LinearLayout>
    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>