将字符串数组列表保存到内部文件目录android

Question

我目前正在开发一个Android应用程序，在运行时生成一些用户数据，这些数据保存在两个ArrayList中。应用程序关闭后，我需要将数据保存到内部存储器中，但在我的logcat中，我总是收到错误IOException file not found。

我很困惑为什么总会发生。以下是我的活动代码。请帮帮我！

    import java.io.BufferedReader;
    import java.io.DataInputStream;
     import java.io.DataOutputStream;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.FileReader;
    import java.io.IOException;
    import java.util.ArrayList;

    import android.content.Intent;
    import android.os.Bundle;
    import android.support.v7.app.ActionBar;
    import android.support.v7.app.ActionBarActivity;
    import android.text.Html;
    import android.view.Menu;
    import android.view.MenuInflater;
    import android.view.View;
    import android.widget.Button;


    public class MainActivity extends ActionBarActivity {


public static ArrayList<String> myArrayList=new ArrayList<String>();
public static ArrayList<String> myArrayListwr=new ArrayList<String>();
static int close=1;

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


    close=1;

     System.out.println("Oncreate called");

    try{ 
     final File dir = new File(getApplicationContext().getFilesDir() + "/file");

        if(!(dir.exists()))
        {

             dir.mkdirs(); //create folders where write files

        }
         final File file = new File(dir+ "/lines.txt");


             if(!(file.exists())) {

                 file.createNewFile();

                } 

             BufferedReader br = new BufferedReader(new FileReader(file));     
                if (br.readLine() == null) {
                    close=0;
                }
                br.close();

    }
    catch (IOException exc) { exc.printStackTrace(); } 




     try {
         if(myArrayList.size()==0 && close!=0)
         {
             System.out.println("retriving data from file lines");


             FileInputStream input =openFileInput("lines.txt");  // Open input stream

         DataInputStream din = new DataInputStream(input);

         int sz = din.readInt(); // Read line count
         for (int i=0;i<sz;i++) { // Read lines
            String line = din.readUTF();
            myArrayList.add(line);
         }
         din.close();
         }
        }
        catch (IOException exc) { exc.printStackTrace(); } 

     try {
         if(myArrayListwr.size()==0 && close!=0)
         {
             System.out.println("retriving data from file lineswr");
             final File dirwr = new File(getApplicationContext().getFilesDir() + "/file");
             if(!dirwr.exists())
             dirwr.mkdirs(); //create folders where write files
             final File filewr = new File(dirwr+ "/lineswr.txt");
             if(!filewr.exists()) {
                 filewr.createNewFile();
            } 
         FileInputStream inputwr = openFileInput("lineswr.txt"); // Open input stream
         DataInputStream dinwr = new DataInputStream(inputwr);
         int szwr = dinwr.readInt(); // Read line count
         for (int iwr=0;iwr<szwr;iwr++) { // Read lines
            String linewr = dinwr.readUTF();
            myArrayListwr.add(linewr);
         }
         dinwr.close();
         }
        }
        catch (IOException exc) { exc.printStackTrace(); } 

    Button phy = (Button) findViewById(R.id.button3);

     Button mat = (Button) findViewById(R.id.button1);

     Button bio = (Button) findViewById(R.id.button2);

     Button chem = (Button) findViewById(R.id.button4);

     }



@Override
public void onBackPressed() {

    super.onBackPressed();


    try {
        if(myArrayList.size()!=0)
        {
            System.out.println("inside on back pressed saving data to lines");
           //Modes: MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITABLE
            String fileName = getApplicationContext().getFilesDir()+"/file/"+ "lines.txt";

           FileOutputStream output = openFileOutput("lines.txt",MODE_PRIVATE);
           DataOutputStream dout = new DataOutputStream(output);
           dout.writeInt(myArrayList.size()); // Save line count
           for(String line : myArrayList) // Save lines
              dout.writeUTF(line);
           dout.flush(); // Flush stream ...
           dout.close(); // ... and close.
        }
    }
        catch (IOException exc) { exc.printStackTrace(); }
    try {
        if(myArrayListwr.size()!=0)
        {
            System.out.println("inside on back pressed saving data to lineswr");
           //Modes: MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITABLE
            String fileNamewr = getApplicationContext().getFilesDir()+"/file/"+ "lineswr.txt";

           FileOutputStream outputwr = openFileOutput("lineswr.txt",MODE_PRIVATE);
           DataOutputStream doutwr = new DataOutputStream(outputwr);
           doutwr.writeInt(myArrayListwr.size()); // Save line count
           for(String linewr : myArrayListwr) // Save lines
              doutwr.writeUTF(linewr);
           doutwr.flush(); // Flush stream ...
           doutwr.close(); // ... and close.
        }
    }
        catch (IOException exc) { exc.printStackTrace(); }

    Intent intent = new Intent(MainActivity.this, MainActivity.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.putExtra("EXIT", true);
    startActivity(intent);

  }

}