正在将文件创建和写入SD卡…“找不到文件”异常即将到来

Question

I'm trying to write a file on SD Card but I'm unable to do it. Can you help me debug the code?

In the Method WriteToFile at this line it's getting exception FileOutputStream fos = new FileOutputStream(fileWithinMyDir); .

package utilities;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import android.content.Context;
import android.os.Environment;
import android.util.Log;

public class LauncherFileOperations {

    public void writeToFile(Context context, Object object, String directoryName, String fileName)
    {

    try{
        File mydir = new File(Environment.getExternalStorageDirectory() + directoryName); //Creating an internal dir; 
        if(!mydir.exists())
            mydir.mkdir();

        File fileWithinMyDir = new File(mydir, fileName+".pList"); //Getting a file within the dir. 
        FileOutputStream fos = new FileOutputStream(fileWithinMyDir);

        ObjectOutputStream oos = new ObjectOutputStream(fos); //Select where you wish to save the file...
        oos.writeObject(object); // write the class as an 'object'
        oos.flush(); // flush the stream to insure all of the information was written to 'save.bin'
        oos.close();// close the stream
    }
    catch(Exception ex) {
        Log.v("LauncherFile OPerations.. writeFailed to Launcherfile",ex.toString());
    }
    }

    public Object readFromFile(Context context, String directoryName, String fileName) {
        Object o = null;
        try{
            File mydir = new File(Environment.getExternalStorageDirectory() + directoryName); //Creating an internal dir; 
            File fileWithinMyDir = new File(mydir, fileName+".pList"); //Getting a file within the dir. 
            FileInputStream fis = new FileInputStream(fileWithinMyDir);
            ObjectInputStream ois = new ObjectInputStream(fis);
            o = ois.readObject();
            ois.close();
        }
        catch(Exception ex) {
            Log.v("LauncherFile operations..readFailed ",ex.toString());
        }
        return o;
    }
}

Answer 1

File mydir = new File(Environment.getExternalStorageDirectory() + "/" +directoryName); //Creating an internal dir; 
    if(!mydir.exists())
        mydir.mkdir();

    File fileWithinMyDir = new File(mydir, fileName+".pList"); //Getting a file within the dir. 
    FileOutputStream fos = new FileOutputStream(fileWithinMyDir);

I think you have to give "/" for the folder structure.. And if you have more then one folders please use mkdirs().