Имея ошибку во время чтения/записи в файл в моем App

Question

MainActivity:

package com.example.jaypatel.file; 

import android.content.Context; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.EditText; 

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

public class MainActivity extends AppCompatActivity { 

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

    public void writeData(View view) 
    { 
     BufferedWriter bufferWriter = null; 
     try { 
      FileOutputStream fileOutputStream = openFileOutput("testFile", Context.MODE_PRIVATE); 
      bufferWriter = new BufferedWriter(new OutputStreamWriter(fileOutputStream)); 
      bufferWriter.write(((EditText)this.findViewById(R.id.editText1)).getText().toString()); 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     }finally 
     { 
      try { 
       bufferWriter.close(); 
      }catch (IOException e){ 
       e.printStackTrace(); 
      } 
     } 
    } 

    public void readData(View view) 
    { 
     BufferedReader bufferedReader = null; 
     StringBuilder result = new StringBuilder(); 
     try { 
      FileInputStream fileInputStream = openFileInput("testFile"); 
      BufferedReader bufferReader = new BufferedReader(new InputStreamReader(fileInputStream)); 
      String line; 
      while ((line=bufferReader.readLine())!=null){ 
       result.append(line + "\r\n"); 
      } 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } catch (IOException e){ 
      e.printStackTrace(); 
     }finally { 
      try { 
       bufferedReader.close(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
     ((EditText)this.findViewById(R.id.editText2)).setText(result); 
    } 
} 

ERROR LOG:

FATAL EXCEPTION: main 
Process: com.example.jaypatel.file, PID: 3382 
java.lang.IllegalStateException: Could not execute method for android:onClick 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) 
    at android.view.View.performClick(View.java:4438) 
    at android.view.View$PerformClick.run(View.java:18422) 
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5017) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
    at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.reflect.InvocationTargetException 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
    at android.view.View.performClick(View.java:4438) 
    at android.view.View$PerformClick.run(View.java:18422) 
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5017) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
    at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
    at com.example.jaypatel.file.MainActivity.readData(MainActivity.java:65) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
    at android.view.View.performClick(View.java:4438) 
    at android.view.View$PerformClick.run(View.java:18422) 
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5017) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
    at dalvik.system.NativeStart.main(Native Method) 

Answer 1

Я получил свою ошибку, как вы должны объявить двухбуквенный считыватель буфера, поэтому он отображает исключение нулевого указателя,

Просто пройти через мой ниже отредактированного код будет работать

public void readData(View view) 
    { 
    BufferedReader bufferedReader = null; 
    StringBuilder result = new StringBuilder(); 
    try { 
     FileInputStream fileInputStream = openFileInput("testFile"); 
     bufferReader = new BufferedReader(new InputStreamReader(fileInputStream)); 
     String line; 
      while ((line=bufferReader.readLine())!=null){ 
       result.append(line + "\r\n"); 
     } 
     } catch (FileNotFoundException e) { 
     e.printStackTrace(); 
     } catch (IOException e){ 
     e.printStackTrace(); 
    }finally { 
     try { 
      bufferedReader.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
    ((EditText)this.findViewById(R.id.editText2)).setText(result); 
} 

Answer 2

Проблема в том, с editText2, вы не инициализируются его. Я предпочитаю вас сделать следующее:

1. Объявить частной области private EditText editText;

2. Bind вид (editText2) внутри onCreate() метода, как этот

   editText = (EditText) findViewById(R.id.editText2);

3. Внутри readData() вместо
   
   ((EditText)this.findViewById(R.id.editText2)).setText(result);
   
   используйте эту строку кода :

   this.editText.setText(result);