class MainActivity

package com.example.choi.mystudy25_3;

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

public class MainActivity extends AppCompatActivity {

    EditText etCountry, etLanguage;
    Button btnSet;


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

        etCountry=(EditText)findViewById(R.id.et_country);
        etLanguage=(EditText)findViewById(R.id.et_language);
        btnSet=(Button)findViewById(R.id.bt_set);



        // 파일저장
        btnSet.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //파일이 없으면 자동으로 만들어 준다.
                //getSharedPreferences(String name, int mode)
                SharedPreferences sp =getSharedPreferences("preference", 0);
                SharedPreferences.Editor editor=sp.edit();

                String country=etCountry.getText().toString();
                String language=etLanguage.getText().toString();

                editor.putString("country", country);
                editor.putString("language", language);
                editor.commit();

            }
        });

        init();

    }


    //초기값 설정
    private void init(){

        //preference 의 임의 값을 가져온다. 없으면 생성
        SharedPreferences sp =getSharedPreferences("preference", 0);
        //preference 저장된 country 값을 가졍 온다. 없으면  country 에 korea 로 생성
        //  String getString(String key, @Nullable String defValue);
        // 값이 없으면 디폴트 값이 korea 이다.
        String country =sp.getString("country", "korea");
        String language =sp.getString("language", "hangeul");

        etCountry.setText(country);
        etLanguage.setText(language);
    }



    // 종료시 자동 저장
    @Override
    protected void onPause() {
        super.onPause();

        SharedPreferences sp =getSharedPreferences("preference", 0);
        SharedPreferences.Editor editor=sp.edit();

        String country=etCountry.getText().toString();
        String language=etLanguage.getText().toString();

        editor.putString("country", country);
        editor.putString("language", language);
        editor.commit();

        Toast.makeText(MainActivity.this, "종료시 자동 저장", Toast.LENGTH_SHORT).show();

    }




}

 

 

R.layout.activity_main

<?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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.choi.mystudy25_3.MainActivity">


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

        <TextView
            android:text="국가"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/textView"
            android:layout_weight="1"
            android:textStyle="normal|bold"
            android:textAlignment="center"
            android:textSize="24sp"
            android:textColor="@color/colorAccent" />

        <EditText
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:ems="10"
            android:id="@+id/et_country"
            android:layout_weight="4" />
    </LinearLayout>

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

        <TextView
            android:text="언어"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/textView2"
            android:layout_weight="1"
            android:textStyle="normal|bold"
            android:textAlignment="center"
            android:textSize="24sp"
            android:textColor="@color/colorAccent" />

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:ems="10"
            android:id="@+id/et_language"
            android:layout_weight="4" />

    </LinearLayout>

    <Button
        android:text="setting"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/bt_set"
        android:background="@android:color/holo_green_dark"
        android:textColor="@android:color/background_light" />


</LinearLayout>