Save and Load Text Files in Android Internal Storage – Simple Notepad

In many Android apps a simple way to persist user notes is to store the text in a private .txt file inside the app’s internal storage. The article demonstrates this by building a minimal notepad that saves and loads its content.

The UI consists of a LinearLayout with a title TextView, an EditText for input, and a Button that triggers the save operation. The layout XML is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".StoreTextActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:gravity="center_horizontal"
        android:textSize="18sp"
        android:textColor="@android:color/black"
        android:text="记事本" />

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#FFC8C8C8" />

    <EditText
        android:id="@+id/edit_text"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:gravity="start"
        android:hint="请输入文本"
        android:inputType="textMultiLine" />

    <Button
        android:id="@+id/btn_save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="saveFile"
        android:text="保存" />

</LinearLayout>

The saveFile(String str) method opens a private file named badao.txt with openFileOutput, writes the supplied string via a BufferedWriter, shows a toast on success, and finally closes both the writer and the stream in a finally block.

public void saveFile(String str) {
    FileOutputStream fos = null;
    BufferedWriter writer = null;
    try {
        fos = openFileOutput("badao.txt", Context.MODE_PRIVATE);
        writer = new BufferedWriter(new OutputStreamWriter(fos));
        writer.write(str);
        Toast.makeText(this, "保存成功", Toast.LENGTH_LONG).show();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (writer != null) {
            try { writer.close(); } catch (IOException e) { e.printStackTrace(); }
        }
        if (fos != null) {
            try { fos.close(); } catch (IOException e) { e.printStackTrace(); }
        }
    }
}

When the activity starts, onCreate calls load() to read any previously saved text. If the returned string is not empty, it populates the EditText and shows a "加载成功" toast.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_store_text);
    editText = findViewById(R.id.edit_text);
    String str = load();
    if (!TextUtils.isEmpty(str)) {
        editText.setText(str);
        Toast.makeText(this, "加载成功", Toast.LENGTH_LONG).show();
    }
}

The load() method opens the same badao.txt with openFileInput, reads each line with a BufferedReader, appends it to a StringBuilder, and returns the combined text. All streams are safely closed in a finally block.

public String load() {
    FileInputStream fis = null;
    BufferedReader reader = null;
    StringBuilder content = new StringBuilder();
    try {
        fis = openFileInput("badao.txt");
        reader = new BufferedReader(new InputStreamReader(fis));
        String line;
        while ((line = reader.readLine()) != null) {
            content.append(line);
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (reader != null) {
            try { reader.close(); } catch (IOException e) { e.printStackTrace(); }
        }
        if (fis != null) {
            try { fis.close(); } catch (IOException e) { e.printStackTrace(); }
        }
    }
    return content.toString();
}

The article also provides the complete StoreTextActivity source, which combines the layout, the save and load methods, and the click handler that forwards the button press to saveFile(editText.getText().toString()). After running the app, entering text, and tapping "保存", the file is created under data/data/your.package.name/files. Relaunching the app shows the previously saved content, confirming that the internal‑storage I/O works as expected.