ストレージにファイルを保存する(内部ストレージ)

外部ストレージに保存する場合はmanifest fileへの記載が必要みたいだけど、内部ストレージなら不要のようだ

1. activity_main.xml (前回の使いまわし)
<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="1">

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editText_dataText"
            android:layout_weight="1.04"
            android:text="good morning" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Save"
            android:id="@+id/button_save"
            android:onClick="onButtonSaveClick" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Load"
            android:id="@+id/button_load"
            android:onClick="onButtonLoadClick" />
    </LinearLayout>
    <!-- 読み込み用 -->
    <TextView
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:id="@+id/labelList"
        />

</LinearLayout>

2. MainActivity.java
package com.example.training.filelocaloperation;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;


public class MainActivity extends Activity {

    TextView tv;
    String LOCAL_FILE = "test.text";

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

        tv = (TextView)findViewById(R.id.editText_dataText);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void onButtonSaveClick(View v){
        String text = tv.getText().toString();
        Toast.makeText(MainActivity.this, new StringBuilder().append("Saveクリックした").append(text).toString(), Toast.LENGTH_SHORT).show();

        OutputStream out;
        try {
            // out = openFileOutput(LOCAL_FILE,MODE_APPEND);    // 追記
            out = openFileOutput(LOCAL_FILE, Context.MODE_PRIVATE);       // 上書き
            PrintWriter writer = new PrintWriter(new OutputStreamWriter(out,"UTF-8"));
            writer.append(text);
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // tv.setText("Saveクリック");
    }

    public void onButtonLoadClick(View v){
        Toast.makeText(MainActivity.this, "Loadクリックした", Toast.LENGTH_SHORT).show();
        // tv.setText("Loadクリック");

        StringBuilder text = new StringBuilder();

        InputStream inputStream;
        String lineBuffer = null;
        try {
            inputStream = openFileInput(LOCAL_FILE);

            BufferedReader reader= new BufferedReader(new InputStreamReader(inputStream,"UTF-8"));
            while( (lineBuffer = reader.readLine()) != null ){
                text.append(lineBuffer);
                Log.d("FileAccess", lineBuffer);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        TextView lblList = (TextView)this.findViewById(R.id.labelList);
        lblList.setText(text);
    }
}