파드레의 요모조모

책과 여기저기 안드로이드 파일 입출력에 관한 자료를 뒤졌는데 모두 잘 안되어 헤메던 중 아래  Happy Programmer분의 글에 주어진 예제가 잘 동작하여 파일 입력과 읽기에 적용해서 성공했습니다.

https://bitsoul.tistory.com/tag/안드로이드 저장장치 내부저장장치 InternalStorage openFileInput openFileOutput [Happy Programmer~]

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main_activity.java

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package com.jstudio.myfile;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class MainActivity extends AppCompatActivity {
    EditText mEdit;

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

        mEdit = (EditText)findViewById(R.id.edittext);
    }

    public void mOnclick(View v){
        FileOutputStream fos=null;
        BufferedOutputStream bos=null;
        DataOutputStream dos = null;

        switch (v.getId()){
            case R.id.save:
                try {
                    String str = "Android File IO test";
                  
                    fos = openFileOutput("text.txt",Context.MODE_APPEND);
                    PrintWriter out = new PrintWriter(fos);
                    out.println(str);
                    out.close();
                    mEdit.setText("write test");

                }catch (FileNotFoundException fnfe) {
                    mEdit.setText("File Not Found 2");
                    return;
                } catch ( Exception e){
                    mEdit.setText("error");
                }

                break;
            case R.id.load:
                try{
                    StringBuffer data1 = new StringBuffer();
                    FileInputStream fis = openFileInput("text.txt");//파일명

                    BufferedReader buffer = new BufferedReader(new InputStreamReader(fis));
                    //BufferedReader buffer = new InputStreamReader(fis);
                    String str = buffer.readLine(); // 파일에서 한줄을 읽어옴
                    while (str != null) {
                        data1.append(str + "\n");
                        str = buffer.readLine();
                    }
                    mEdit.setText(data1);
                    buffer.close();
                                        mEdit.setText(new String(data));*/
                } catch (Exception e){
                    mEdit.setText("File Not Found");
                }
                break;
            case R.id.loadres:
                try{
                    InputStream MyInput = getResources().openRawResource(R.raw.test);
                    byte[] data = new byte[MyInput.available()];
                    while (MyInput.read(data) !=-1){;}
                    MyInput.close();
                    mEdit.setText(new String(data));
                } catch (Exception e){;}
                break;
            case R.id.delete:
                if (deleteFile("text.txt")) {
                    mEdit.setText("delete success");
                } else {
                    mEdit.setText("delete Failed");
                }
                break;
        }}
}

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activity_main.xml

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<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat 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"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="mOnclick"
        android:text="save"/>
    <Button
        android:id="@+id/load"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="mOnclick"
        android:text="load"/>
    <Button
        android:id="@+id/loadres"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="mOnclick"
        android:text="loadres"/>
    <Button
        android:id="@+id/delete"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="mOnclick"
        android:text="delete"/>
    <EditText
        android:id="@+id/edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</androidx.appcompat.widget.LinearLayoutCompat>