Develop Reference

Android - openFileInput() NullPointerException [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 3 years ago.
I'm trying to generate a code as string in my android application and save it to a text file. When you press a Share button, the code should be read from the text file and be copied to the clipboard.
I guess I'm not understanding something about acivity/context.
Of course I read in the documentation about it, but I can't figure out the problem. Hope you guys could help me!
FileSystem.java
package com.niclasjaksch.shoppinglist;
import android.content.Context;
import androidx.appcompat.app.AppCompatActivity;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
class FileSystem extends AppCompatActivity {
static String filename = "shoppinglist_code.txt";
void Create() {
try {
FileOutputStream fOut = openFileOutput(filename, Context.MODE_PRIVATE);
String str = Utility.randomString(10);
fOut.write(str.getBytes());
fOut.close();
} catch (IOException e) {
e.printStackTrace();
}
}
String Read() {
String result = "";
try {
FileInputStream fin = openFileInput(filename);
int c;
while( (c = fin.read()) != -1){
result += c;
}
fin.close();
} catch (Exception e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
return result;
}
void Clear() {
try {
File dir = getFilesDir();
File file = new File(dir, filename);
file.delete();
} catch (Exception e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
Share.java
package com.niclasjaksch.shoppinglist;
import android.content.ClipData;
import androidx.appcompat.app.AppCompatActivity;
class Share extends AppCompatActivity {
android.content.ClipboardManager clipboardManager = null;
FileSystem fs = new FileSystem();
void Share() {
String code = fs.Read();
if(code == "" || code == null) {
fs.Create();
code = fs.Read();
}
ClipData clipData = ClipData.newPlainText("Source Text", code);
clipboardManager.setPrimaryClip(clipData);
}
}
MainActivity.java
...
Share share = new Share();
...
#Override
public boolean onOptionsItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.item_share:
share.Share();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
Getting a NullPointerException in this line:
FileOutputStream fOut = openFileOutput(filename, Context.MODE_PRIVATE);

Only create subclasses of AppCompatActivity for actual UI work, where you will start that activity using startActivity() or startActivityForResult().
Move those methods to a real activity, such as MainActivity, and get rid of the Share and FileSystem classes.

First things first, you shouldn't extend AppCompatActivity for FileSystem and Share.
What's happening is that the openFileOutput is taking the FileSystem object (this) as it's context. When in reality it wouldn't count as a separate activity.
You could either do as CommonWare suggest and remove the classes FileSystem and Share, and move their functions to the MainActivity. Or you could explicitly pass the context from the MainActivity.

Parameter passed from callee but comes as null in the method definition

I am basically trying to create an unzip function. I called the function with parameters in the block below:
UnzipUtility unzipUtility = new UnzipUtility();
try {
unzipUtility.unzip(localFilePath, parentPath);
} catch (IOException e) {
e.printStackTrace();
}
Definition of the method is in a class UnzipUtility, the code as follows:
public void unzip(String zipFilePath, String destDirectory) throws IOException {
File destDir = new File(destDirectory);
if (!destDir.exists()) {
destDir.mkdir();
}
ZipInputStream zipIn = new ZipInputStream(new FileInputStream(zipFilePath));
ZipEntry entry = zipIn.getNextEntry();
// iterates over entries in the zip file
while (entry != null) {
String filePath = destDirectory + File.separator + entry.getName();
if (!entry.isDirectory()) {
// if the entry is a file, extracts it
extractFile(zipIn, filePath);
} else {
// if the entry is a directory, make the directory
File dir = new File(filePath);
dir.mkdir();
}
zipIn.closeEntry();
entry = zipIn.getNextEntry();
}
zipIn.close();
}
But during runtime, though parameters are passed properly in the main class, the values shows up as null in the unzip method.
Please help with this
The main class is as follows:
package com.example.sftpconnection;
import android.annotation.SuppressLint;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.SftpException;
//import java.io.BufferedOutputStream;
import java.io.File;
//import java.io.FileOutputStream;
import java.io.IOException;
//import java.io.OutputStream;
import java.util.List;
import com.example.sftpconnection.UnzipUtility;
public class SFTPActivity extends AppCompatActivity {
private String fileName = "1234.zip";
private String localFilePath;
private String parentPath;
#SuppressLint("StaticFieldLeak")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sftp);
new AsyncTask<Void, Void, List<String>>() {
#Override
protected List<String> doInBackground(Void... params) {
try {
Downloader(fileName);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}.execute();
UnzipUtility unzipUtility = new UnzipUtility();
try {
unzipUtility.unzip(localFilePath, parentPath);
} catch (IOException e) {
e.printStackTrace();
}
}
public void Downloader(String fileName) {
String user = "1234";
String pass = "1234";
String host = "1234";
int portNum = 22;
JSch jsch = new JSch();
Session session;
try {
session = jsch.getSession(user,host,portNum);
session.setConfig("StrictHostKeyChecking", "no");
session.setPassword(pass);
session.connect();
Channel channel = session.openChannel("sftp");
channel.connect();
ChannelSftp sftpChannel = (ChannelSftp) channel;
File localFile = File.createTempFile("1234",".zip");
sftpChannel.get(fileName,localFile.getAbsolutePath());
//sftpChannel.get(fileName);
Log.d(fileName, " has been downloaded");
sftpChannel.exit();
session.disconnect();
localFilePath = localFile.getAbsolutePath();
parentPath = localFile.getParent();
} catch (JSchException | IOException | SftpException e) {
e.printStackTrace();
}
}
}
I edited the data fields for security reasons.

Could cut the following lines:
UnzipUtility unzipUtility = new UnzipUtility();
try {
unzipUtility.unzip(localFilePath, parentPath);
} catch (IOException e) {
e.printStackTrace();
}
paste just below the following line in class SFTPActivity:
Downloader(fileName);
of method doInBackground.
Actually the method doInBackground() runs in different thread from the thread in which the method onCreate runs. You attempt to use the variables before the method Downloader(fileName) could do its job. This is the reason why you see null values in variables like: localFilePath and parentPath

The reason why your code does not work is because at the time of running this line:
unzipUtility.unzip(localFilePath, parentPath);
the variables localFilePath and parentPath have not been set.
You might argue that they are set in the method Downloader, which is called before the unzip line. Unfortunately, this is not true. In this case, code execution is not linear because you are using an AsyncTask. The stuff in the async task runs simultaneously with the lines that come after it.
Your download call is not going to finish before unzipUtility.unzip is called, because downloading takes a huge amount of time, compared to creating a new UnzipUtility object.
This is why localFilePath and parentPath are null.
One way to solve this problem is to move the unzip logic into the async task as well:
new AsyncTask<Void, Void, List<String>>() {
#Override
protected List<String> doInBackground(Void... params) {
try {
Downloader(fileName);
UnzipUtility unzipUtility = new UnzipUtility();
unzipUtility.unzip(localFilePath, parentPath);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}.execute();
Another way is to override onPostExecute in the AsyncTask as well:
new AsyncTask<Void, Void, List<String>>() {
// doInBackground goes here...
#Override
protected void onPostExecute(Long result) {
try {
UnzipUtility unzipUtility = new UnzipUtility();
unzipUtility.unzip(localFilePath, parentPath);
} catch (Exception e) {
e.printStackTrace();
}
}
}

JFileChooser showSaveDialog not working sometimes

I'm using Netbeans 7.2 on OS X 10.9. The JFileChooser.showSaveDialog() fails on certain occasions. Before I call the showSaveDialog, I call showOpenDialog to open an .srt file. The show dialog fails only when I open certain files esp. from /Volumes/.. on a mounted device. Here's the code:
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFileChooser;
import javax.swing.filechooser.FileNameExtensionFilter;
import org.apache.commons.io.FilenameUtils;
public class FileSaver extends JFileChooser {
private int result;
private File subFile;
private File save;
private File filename;
private String rectifiedSub;
private FileNameExtensionFilter filter;
public FileSaver(File subFile, String rectifiedSub) {
this.subFile = subFile;
this.rectifiedSub = rectifiedSub;
filename = new File(System.getProperty("user.home"));
filter = new FileNameExtensionFilter("Subtitle Files (*.srt)", "srt");
}
public void createAndShowGUI() {
System.out.println("6");
this.setDialogTitle("Select destination");
System.out.println("6");
this.setCurrentDirectory(filename);
System.out.println("6");
this.setSelectedFile(new File(subFile.getName()));
System.out.println("6");
this.setFileFilter(filter);
System.out.println("6");
result = this.showSaveDialog(this);
System.out.println("6");
if(result == JFileChooser.APPROVE_OPTION) {
save = fixExtension(this.getSelectedFile());
write(save);
}
this.setVisible(true);
}
public void write(File save) {
FileWriter fw = null;
try {
fw = new FileWriter(save);
fw.write(rectifiedSub);
} catch (IOException ex) {
Logger.getLogger(FileSaver.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
fw.close();
} catch (IOException ex) {
Logger.getLogger(FileSaver.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
public File fixExtension(File file) {
if(!FilenameUtils.getExtension(file.getName()).equalsIgnoreCase(".srt"))
file = new File(file.getParentFile(), FilenameUtils.getBaseName(file.getName()).concat(".srt"));
return file;
}
}
Output:
6
6
6
6
6
It stops at the 6 before the line result = this.shhowSaveDialog(this);. The program freezes after that and the save dialog doesn't show up. It works perfectly fine on some files. Somebody tell me whats happening ?
Git: https://github.com/Jimmy-666/Subzero.git

Android External File Inconsistently Appearing

I'm using an IntentService to append single NMEA strings to a log file stored in the external public storage on an Android device, but I'm getting inconsistent behavior.
First off the log file does not appear when the device is connected for USB debugging. I read that many Android devices cannot write to external storage when connected via USB, but even when it is run disconnected from USB, it may take several times of turning it on and off and rerunning the applications before the log file appears in the file system. If I do not clear the log, I still have to restart the phone before it will begin appending to the file again.
How can I get the file to appear consistently everytime?
import android.app.IntentService;
import android.content.Intent;
public class LogFileService extends IntentService {
DebugLog debug = new DebugLog("LogFileService");
public static final String GPS_STR = "GPS_STR";
public static final String FILE_PATH = "FILE_PATH";
public static final String FILE_NAME = "gps_data.txt";
public LogFileService() {
super("LogFileService");
}
#Override
protected void onHandleIntent(Intent intent) {
debug.log("Handling intent");
String data = intent.getStringExtra(GPS_STR);
debug.log("Writing " + data);
GpsLogFile logFile = new GpsLogFile(FILE_NAME);
logFile.open();
logFile.write(data);
logFile.close();
}
#Override
public void onCreate() {
super.onCreate();
debug.log("Created");
}
}
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import android.content.Context;
import android.os.Environment;
public class GpsLogFile {
DebugLog debug = new DebugLog("LogFile");
private File filePath = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOWNLOADS
);
private File logFile = null;
private String fileName = null;
private PrintWriter fileOut = null;
public GpsLogFile(String name) {
fileName = name;
}
public void open() {
try {
filePath.mkdirs();
if (!isExternalMediaAvailable()) {
throw new IOException("External media not available.");
}
logFile = new File(filePath, fileName);
//logFile.mkdirs();
if (!logFile.exists()) {
logFile.createNewFile();
}
fileOut = new PrintWriter(
new FileOutputStream(logFile.getAbsolutePath(), true)
);
} catch (IOException e) {
debug.log("Unable to open file.");
debug.log(e.getMessage());
}
}
public void write(String data) {
debug.log("Writing to " + logFile.getAbsolutePath() + " " + data);
try {
fileOut.write(data);
//fileOut.newLine();
checkPrintWriterError(fileOut);
fileOut.flush();
} catch (IOException e) {
debug.log("Unable to write");
debug.log(e.getMessage());
}
}
public void close() {
if (null != fileOut) {
try {
fileOut.close();
checkPrintWriterError(fileOut);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
private void checkPrintWriterError(PrintWriter writer) throws IOException {
if (true == writer.checkError()) {
throw new IOException("Print writer error.");
}
}
}

file upload in FileNet?

I'm writing code to upload a file in FileNet.
A standalone java program to take the some inputs, and upload it in FileNet. I'm new to FileNet. Can you help me out, How to do it?

You can use Document.java provided by IBM for your activities and many other Java classes
package fbis.apitocasemanager;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import com.user.DocumentUtil;
public class Addfilescasemanager {
/**
* #param args
*/
public static void addfiles_toicm(String directory, String lFolderPath)
{
try {
DocumentUtil.initialize();
String path = directory;
System.out.println("This is the path:..............................."
+ path);
String file_name;
File folder = new File(directory);
File[] listOfFiles = folder.listFiles();
for (int i = 0; i < listOfFiles.length; i++)
{
if (listOfFiles[i].isFile())
{
file_name = listOfFiles[i].getName();
System.out.println(file_name);
String filePaths = directory + file_name;
// File file = new File("C:\\FNB\\att.jpg");
File file = new File(filePaths);
InputStream attStream = null;
attStream = new FileInputStream(file);
DocumentUtil.addDocumentWithStream(lFolderPath, attStream,
"image/jpeg", file_name, "Document");
}
}
} catch (FileNotFoundException e)
{
e.printStackTrace();
}
}//end of method
public static void addfile_toicm(File file_name, String lFolderPath)
{
try {
DocumentUtil.initialize();
InputStream attStream = null;
attStream = new FileInputStream(file_name);
DocumentUtil.addDocumentWithStream(lFolderPath, attStream,
"image/jpeg", file_name.getName(), "Document");
System.out.println("File added successfully");
} catch (Exception e)
{
System.out.println(e.getMessage());
}
}//end of method
public static void main(String nag[])
{
addfiles_toicm("E:\\FSPATH1\\BLR_14122012_001F1A\\","/IBM Case Manager/Solution Deployments/Surakshate Solution for form 2/Case Types/FISB_FactoriesRegistration/Cases/2012/12/06/16/000000100103");
}
}
and my DocumentUtil class is
package com.user;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import javax.security.auth.Subject;
import com.filenet.api.collection.ContentElementList;
import com.filenet.api.constants.AutoClassify;
import com.filenet.api.constants.AutoUniqueName;
import com.filenet.api.constants.CheckinType;
import com.filenet.api.constants.DefineSecurityParentage;
import com.filenet.api.constants.RefreshMode;
import com.filenet.api.core.Connection;
import com.filenet.api.core.ContentTransfer;
import com.filenet.api.core.Document;
import com.filenet.api.core.Domain;
import com.filenet.api.core.Factory;
import com.filenet.api.core.Folder;
import com.filenet.api.core.ObjectStore;
import com.filenet.api.core.ReferentialContainmentRelationship;
import com.filenet.api.util.UserContext;
public class DocumentUtil {
public static ObjectStore objectStore = null;
public static Domain domain = null;
public static Connection connection = null;
public static void main(String[] args)
{
initialize();
/*
addDocumentWithPath("/FNB", "C:\\Users\\Administrator\\Desktop\\Sample.txt.txt",
"text/plain", "NNN", "Document");
*/
File file = new File("E:\\Users\\Administrator\\Desktop\\TT.txt");
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
addDocumentWithStream("/FNB", fis, "text/plain", "My New Doc", "Document");
}
public static void initialize()
{
System.setProperty("WASP.LOCATION", "C:\\Progra~1\\IBM\\WebSphere\\AppServer\\profiles\\AppSrv01\\installedApps\\P8Node01Cell\\FileNetEngine.ear \\cews.war\\WEB-INF\\classes\\com\\filenet\\engine\\wsi");
System.setProperty("SECURITY.AUTH.LOGIN.CONFIG",
"C:\\Progra~1\\IBM\\WebSphere\\AppServer\\profiles\\AppSrv01\\installedApps\\P8Node01Cell\\FileNetEngine.ear\\client-download.war\\FileNet\\Download\\dap501.153\\jaas.conf.wsi");
System.setProperty(":SECURITY.AUTH.LOGIN.CONFIG",
"C:\\Progra~1\\IBM\\WebSphere\\AppServer\\profiles\\AppSrv01\\installedApps\\P8Node01Cell\\FileNetEngine.ear\\client-download.war\\FileNet\\Download\\dap501.153\\jaas.conf.wsi");
System.setProperty("java.security.auth.login.config","C:\\Progra~1\\IBM\\WebSphere\\AppServer\\java\\jre");
connection = Factory.Connection.getConnection(CEConnection.uri);
Subject sub = UserContext.createSubject(connection,
com.user.CEConnection.username, CEConnection.password,
CEConnection.stanza);
UserContext.get().pushSubject(sub);
domain = Factory.Domain.getInstance(connection, null);
objectStore = Factory.ObjectStore.fetchInstance(domain, "TARGET", null);
System.out.println("\n\n objectStore--> " + objectStore.get_DisplayName());
}
public static void addDocumentWithPath(String folderPath, String filePath,
String mimeType, String docName, String docClass) {
Folder folder = Factory.Folder.fetchInstance(objectStore,
folderPath, null);
System.out.println("\n\n Folder ID: " + folder.get_Id());
// Document doc = Factory.Document.createInstance(os, classId);
Document doc = CEUtil.createDocWithContent(new File(filePath), mimeType,
objectStore, docName, docClass);
doc.save(RefreshMode.REFRESH);
doc = CEUtil.createDocNoContent(mimeType, objectStore, docName, docClass);
doc.save(RefreshMode.REFRESH);
CEUtil.checkinDoc(doc);
ReferentialContainmentRelationship rcr = CEUtil.fileObject(objectStore, doc, folderPath);
rcr.save(RefreshMode.REFRESH);
}
public static void addDocumentWithStream(String folderPath,
InputStream inputStream, String mimeType,
String docName, String docClass) {
Folder folder = Factory.Folder.fetchInstance(objectStore,
folderPath, null);
System.out.println("\n\n Folder ID: " + folder.get_Id());
// Document doc = Factory.Document.createInstance(os, classId);
Document doc = Factory.Document.createInstance(objectStore, null);
ContentElementList contEleList = Factory.ContentElement.createList();
ContentTransfer ct = Factory.ContentTransfer.createInstance();
ct.setCaptureSource(inputStream);
ct.set_ContentType(mimeType);
ct.set_RetrievalName(docName);
contEleList.add(ct);
doc.set_ContentElements(contEleList);
doc.getProperties().putValue("DocumentTitle", docName);
doc.set_MimeType(mimeType);
doc.checkin(AutoClassify.AUTO_CLASSIFY, CheckinType.MAJOR_VERSION);
doc.save(RefreshMode.REFRESH);
ReferentialContainmentRelationship rcr = folder.file(doc,
AutoUniqueName.AUTO_UNIQUE, docName,
DefineSecurityParentage.DO_NOT_DEFINE_SECURITY_PARENTAGE);
rcr.save(RefreshMode.REFRESH);
/*
doc.save(RefreshMode.REFRESH);
doc = CEUtil.createDocNoContent(mimeType, objectStore, docName, docClass);
CEUtil.checkinDoc(doc);
ReferentialContainmentRelationship rcr = CEUtil.fileObject(objectStore, doc, folderPath);
rcr.save(RefreshMode.REFRESH);
*/
}
public static ObjectStore getObjecctStore()
{
if (objectStore != null) {
return objectStore;
}
// Make connection.
com.filenet.api.core.Connection conn = Factory.Connection
.getConnection(CEConnection.uri);
Subject subject = UserContext.createSubject(conn,
CEConnection.username, CEConnection.password, null);
UserContext.get().pushSubject(subject);
try {
// Get default domain.
Domain domain = Factory.Domain.getInstance(conn, null);
// Get object stores for domain.
objectStore = Factory.ObjectStore.fetchInstance(domain, "TARGET",
null);
System.out.println("\n\n Connection to Content Engine successful !!");
} finally {
UserContext.get().popSubject();
}
return objectStore;
}
}

The above answer is extremely good. Just wanted to save people some time but I don't have the points to comment so am adding this as an answer.
Eclipse wasted a lot of my time getting the above to work because it suggested the wrong classes to import. Here's the list of correct ones:
import com.filenet.api.collection.ContentElementList;
import com.filenet.api.constants.AutoClassify;
import com.filenet.api.constants.AutoUniqueName;
import com.filenet.api.constants.CheckinType;
import com.filenet.api.constants.DefineSecurityParentage;
import com.filenet.api.constants.RefreshMode;
import com.filenet.api.core.Document;
import com.filenet.api.core.ObjectStore;
import com.filenet.api.core.ContentTransfer;
import com.filenet.api.core.Folder;
import com.filenet.api.core.Factory;
import com.filenet.api.core.ReferentialContainmentRelationship;