To save file in a directory of Internal Storage

Here's a code of MainActivity.java to save a file named filename.txt in App's Internal Storage, which is working fine.

package com.bla.smthing;


import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class MainActivity extends Activity {

    EditText textmsg;
    static final int READ_BLOCK_SIZE = 100;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textmsg=(EditText)findViewById(R.id.editText1);
    }

    // write text to file
    public void WriteBtn(View v) {
        // add-write text into file
        try {
            FileOutputStream fileout=openFileOutput("mytextfile.txt", MODE_PRIVATE);
            OutputStreamWriter outputWriter=new OutputStreamWriter(fileout);
            outputWriter.write(textmsg.getText().toString());
            outputWriter.close();

            //display file saved message
            Toast.makeText(getBaseContext(), "File saved successfully!",
                    Toast.LENGTH_SHORT).show();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // Read text from file
    public void ReadBtn(View v) {
        //reading text from file
        try {
            FileInputStream fileIn=openFileInput("mytextfile.txt");
            InputStreamReader InputRead= new InputStreamReader(fileIn);

            char[] inputBuffer= new char[READ_BLOCK_SIZE];
            String s="";
            int charRead;

            while ((charRead=InputRead.read(inputBuffer))>0) {
                // char to string conversion
                String readstring=String.copyValueOf(inputBuffer,0,charRead);
                s +=readstring;
            }
            InputRead.close();
            textmsg.setText(s);


        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

I am able to see the file by File Explorer of Android Studio. How can I save the file in a directory say files/Somefolder/otherfolderchild/filename.txt?

Currently, it is saving as files/filename.txt Do I need to create additional parent file directories for that?

Try this it might help you. For the above marshmallow version please check the write permissions.

public void saveToExternalStorage() {
String fullPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/directoryName";
try
{
    File dir = new File(fullPath);
    if (!dir.exists()) {
    dir.mkdirs();
    }
    OutputStream fOut = null;
    File file = new File(fullPath, "fileName.txt");
    if(file.exists())
        file.delete();
    file.createNewFile();
    fOut = new FileOutputStream(file);
    fOut.flush();
    fOut.close();
}
catch (Exception e)
{
    Log.e("saveToExternalStorage()", e.getMessage());
}

}