PowenKo, Android Tutorial 065-1, File, read and write, get last Modified time

package com.powenko.Tutorial_File_read_write;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Calendar;
import java.util.Date;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class Tutorial_File_read_write extends Activity {
    /** Called when the activity is first created. */
	protected String filePath="myfilename.txt";
	
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        
        file_write(filePath,"PowenKo.com  sample code");
        try {
			file_read(filePath);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		// 時間有問題
		File file = new File(filePath);
		Date lastModDate = new Date(file.lastModified());
		Log.i("powen:","File last modified: "+ lastModDate.toString());
		long dateModified=file.lastModified();
	
		
		Date date = new Date(dateModified*1000);
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		String timeline = String.format("%1$4d" + "-" + "%2$02d",calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH) + 1);
		
		
		
		
        
    }
   protected void file_read(String i_filePath) throws IOException{
	   // try opening the myfilename.txt
	   String line;
	   try {
	     // open the file for reading
	     InputStream instream = openFileInput(i_filePath);
	  
	     
	     // if file the available for reading
	     if (instream!=null) {
	       // prepare the file for reading
	       InputStreamReader inputreader = new InputStreamReader(instream);
	       BufferedReader buffreader = new BufferedReader(inputreader);

	        StringBuffer stringBuffer = new StringBuffer("");

	       
	      // line =buffreader.readLine();
	       char[] buffer = new char[3072];
	        int len1 = 0;
	        while ( (len1 = buffreader.read(buffer)   ) != -1 ) 
	        {
	            String buff = new String(buffer,0,len1);
	            stringBuffer.append(buff);
	        }
	        String stranica = new String(stringBuffer);
	       // c.disconnect();
	        buffreader.close();

	        
	        
	        
	  
	     }
	  
	     // close the file again
	   //  instream.close();
	     
	   } catch (java.io.FileNotFoundException e) {
	     // do something if the myfilename.txt does not exits
	   }
   }
   protected void file_write(String i_filePath,String mySettings){
    	
    	// try to write the content
    	try {
    	  // open myfilename.txt for writing
    	  OutputStreamWriter out = new OutputStreamWriter(openFileOutput(i_filePath,0));
    	  // write the contents on mySettings to the file
    	  out.write(mySettings);
    	  // close the file
    	  out.close();
    	} catch (java.io.IOException e) {
    	  //do something if an IOException occurs.
    	}
    }
 
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.powenko.Tutorial_File_read_write"
      android:versionCode="1"
      android:versionName="1.0">


    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".Tutorial_File_read_write"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

sample code:
Tutorial_File_read_write