java - 尝试通过列表从 .txt 中删除一行时应用强制关闭

Question

我正在尝试从 .txt 文件中删除一行，当用户单击按钮并收到提示时，但我正在强制关闭。

删除代码如下:

package ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds;

import android.app.ActionBar;
import android.util.Log;
import android.view.View.OnClickListener;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.widget.DrawerLayout;
import android.text.method.ScrollingMovementMethod;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;


public class viewMeds extends Activity {



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        setTitle("View Medications");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_meds);


        String SDRoot = Environment.getExternalStorageDirectory().getPath();
        final File output = new File(SDRoot,"output.txt");
        //Get the text file

        //Read text from file


        StringBuilder text = new StringBuilder();

        try {
            BufferedReader br = new BufferedReader(new FileReader(output));
            String line;

            while ((line = br.readLine()) != null) {
                    text.append("Medication: " + line);
                    text.append("\n\n");

            }
        }
        catch (IOException e) {
            //You'll need to add proper error handling here
        }

        //Find the view by its id
        TextView tv = (TextView)findViewById(R.id.viewMedsTxt);
        tv.setMovementMethod(new ScrollingMovementMethod());

        //Set the text
        tv.setText(text);

        Button delete = (Button)findViewById(R.id.deleteMed);
        delete.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {


                final AlertDialog.Builder alert = new AlertDialog.Builder(viewMeds.this);

                alert.setTitle("Delete a Medication");
                alert.setMessage("Enter Which Line The Desired Medication Is On:");

                // Set an EditText view to get user input
                final EditText input = new EditText(viewMeds.this);
                alert.setView(input);

                alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        int value = -1;

                        try {
                            value = Integer.parseInt(input.toString());
                            value = value -1;
                            Log.i("", value + " is a number");
                        } catch (NumberFormatException e) {
                            alert.setMessage("That wasn't a number.\nEnter Which Line The Desired Medication Is On:");
                        }
                        // Do something with value!

                        try {
                            removeLine(output,value);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                });

                alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        // Canceled.
                    }
                });

                alert.show();


            }
        });

    }


    public void removeLine(final File file, final int lineIndex) throws IOException{
        final List<String> lines = new LinkedList<>();
        final Scanner reader = new Scanner(new FileInputStream(file), "UTF-8");
        while(reader.hasNextLine())
            lines.add(reader.nextLine());
        reader.close();
        assert lineIndex >= 0 && lineIndex <= lines.size() - 1;
        lines.remove(lineIndex);
        final BufferedWriter writer = new BufferedWriter(new FileWriter(file, false));
        for(final String line : lines)
            writer.write(line);
        writer.flush();
        writer.close();
    }



    public void restoreActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setTitle("View Medications");
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case R.id.action_settings:
                Intent prefIntent = new Intent("android.intent.action.PREFS");
                startActivity(prefIntent);
                break;
            case R.id.exit:
                finish();
                break;

        }

        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        public PlaceholderFragment() {
        }
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.activity_main, container, false);
        return rootView;
    }

   /* @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ((MainActivity) activity).onSectionAttached(
                getArguments.getInt(ARG_SECTION_NUMBER));
    }*/
}

这是当我输入 1 时 logcat 输出的内容:

10-20 21:15:29.554  10258-10258/ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds, PID: 10258
    java.lang.IndexOutOfBoundsException
            at java.util.LinkedList.remove(LinkedList.java:660)
            at ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds.viewMeds.removeLine(viewMeds.java:136)
            at ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds.viewMeds$1$1.onClick(viewMeds.java:107)
            at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5034)
            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:1270)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1086)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)

非常感谢。

编辑:写入文件的代码:

String SDRoot = Environment.getExternalStorageDirectory().getPath();
            final File output = new File (SDRoot,"output.txt");

        if(!output.exists()){
            try {
                output.createNewFile();
                Context context = getApplicationContext();
                CharSequence text = "Output File Created!";
                int duration = Toast.LENGTH_LONG;

                Toast fileCreated = Toast.makeText(context, text, duration);
                fileCreated.show();
            } catch (IOException e) {
                Context context = getApplicationContext();
                CharSequence text = "Output File Not Created!";
                int duration = Toast.LENGTH_LONG;

                Toast fileNotCreated = Toast.makeText(context, text, duration);
                fileNotCreated.show();
                e.printStackTrace();
            }
        }


            Button addbutton = (Button)findViewById(R.id.addMeds);
        addbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String outputLine = "\n" + medOut.getText() + " "+ doseOut.getText() + dayout.getText() +":" + " "+ ":" + timeOut.getText();

                try {
                    FileOutputStream fOut = new FileOutputStream(output, true);
                    OutputStreamWriter myOutputStreamWriter = new OutputStreamWriter(fOut);
                    myOutputStreamWriter.append(outputLine);
                    myOutputStreamWriter.flush();
                    myOutputStreamWriter.close();
                    Toast.makeText(getBaseContext(), "Medication Added",
                            Toast.LENGTH_SHORT).show();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                    Toast.makeText(getBaseContext(), e.getMessage(),
                            Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                    Toast.makeText(getBaseContext(), e.getMessage(),
                            Toast.LENGTH_SHORT).show();
                }






            }
        });

Answer 1

尝试替换这段代码:

assert lineIndex >= 0 && lineIndex <= lines.size() - 1;
lines.remove(lineIndex);

使用此代码:

if(lineIndex >= 0 && lineIndex <= lines.size() - 1)
   lines.remove(lineIndex);