4.Android development file read and write

package cn.fc.filepersistencetest;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.text.TextUtils;
import android.widget.EditText;
import android.widget.Toast;

import org.w3c.dom.Text;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class MainActivity extends AppCompatActivity {
    
    

    private EditText edit;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        edit = (EditText)findViewById(R.id.edit);
        String inputText = load();
        if(!TextUtils.isEmpty(inputText)){
    
    
            edit.setText(inputText);
            edit.setSelection(inputText.length());
            Toast.makeText(this, "Restoring successed", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onDestroy(){
    
    
        super.onDestroy();
        String inputText = edit.getText().toString();
        save(inputText);
    }

    // 用于存储数据
    public void save(String inputText){
    
    
        FileOutputStream out = null;
        BufferedWriter writer = null;

        try{
    
    
            out = openFileOutput("data", Context.MODE_PRIVATE);
            writer = new BufferedWriter(new OutputStreamWriter(out));
            writer.write(inputText);

        }catch (IOException e){
    
    
            e.printStackTrace();
        } finally {
    
    
            try{
    
    
                if(writer != null){
    
    
                    writer.close();
                }
            } catch (IOException e){
    
    
                e.printStackTrace();
            }
        }
    }

    public String load(){
    
    
        FileInputStream in = null;
        BufferedReader reader = null;
        StringBuilder content = new StringBuilder();

        try{
    
    
            in = openFileInput("data");
            reader = new BufferedReader(new InputStreamReader(in));
            String line = "";
            while ((line = reader.readLine()) != null){
    
    
                content.append(line);
            }
        } catch (IOException e){
    
    
            e.printStackTrace();
        } finally {
    
    
            try{
    
    
                if (reader != null){
    
    
                    reader.close();
                }
            } catch (IOException e){
    
    
https://github.com/MrDHY/android-develop                e.printStackTrace();
            }

        }
        return content.toString();
    }
}

project address