try {
FileInputStream f = new FileInputStream("proj.bin");
ObjectInputStream o = new ObjectInputStream(f);
this.FigureList = (ArrayList<Figure>) o.readObject();
o.close();
} catch (Exception x) {
}
this.addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
try {
FileOutputStream f = new FileOutputStream("proj.bin");
ObjectOutputStream o = new ObjectOutputStream(f);
o.writeObject(FigureList);
o.flush();
o.close();
} catch (Exception x) {
}
System.exit(0);
}
});
I've been using this code to save the infos of my panel(Figure position, color and those kind of things), so whenever I run the code again, there will be things already there. Can save it as SVG and use this svg file in others apps? I've tried to change ".bin" for ".svg" but it seems it's not that easy.
You can see my whole code here
Related
I am working on a debuging csv output inside an event driven java application. I define my filewriter like this on init.
public File csvFile;
public FileWriter fileWriter;
then I initialies them
this.csvFile = new File("c:\\missingitems.csv");
this.fileWriter = null;
try {
this.fileWriter = new FileWriter(this.csvFile);
StringBuilder line = new StringBuilder();
line.append("Date, ItemId");
line.append("\n");
this.fileWriter.write(line.toString());
} catch (IOException e) {
e.printStackTrace();
}
then within my actual program logic this gets called for every timestep in my data
for(Long item : this.items) {
StringBuilder line = new StringBuilder();
line.append(event.getDateTime().toLocalDate().toString() + "," +item.intValue());
line.append("\n");
try {
this.fileWriter.write(line.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
on exit of my program I call
try {
this.fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
However this seems to be only working if i close the filewriter after each append. Is there a way of keeping the file open and just append to it, I would also like to not loose my data in case my application crashes. I am a python guy and not super familiar with java.
I am performing a project, where so far in the discipline, we can not use database to persist the data. I am persisting the data in .tmp files. The first time I persisted the list of doctors, and it worked, but now that I'm trying to persist the patient user data, but this error happens, that file is not found.
These are my load, anda save methods in the class "SharedResources":
public void loadUserPatient(Context context) {
FileInputStream fis1;
try {
fis1 = context.openFileInput("patient.tmp");
ObjectInputStream ois = new
ObjectInputStream(fis1);
userPatient = (UserPatient) ois.readObject();
ois.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ClassNotFoundException e) {
e.printStackTrace();
}
}
public void saveUserPatient(Context context) {
FileOutputStream fos1;
try {
fos1 = context.openFileOutput("patient.tmp",
Context.MODE_PRIVATE);
ObjectOutputStream oos =
new ObjectOutputStream(fos1);
oos.writeObject(userPatient);
oos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
here is the whole class: https://ideone.com/f3c74u
the error is happening on line 16 of MainActivity:
SharedResources.getInstance().loadUserPatient(this);
here is the whole class "Main": https://ideone.com/OyiljP
And I think this error is ocurring because of the 52nd line of the UserPatientAdd class:
SharedResources.getInstance().getUserPatient();
because when I work with an ArrayList, I put an add at the end of the line, like:SharedResources.getInstance().getDoctors().add(doctor);
And I get confused on how to proceed when I deal only with a user.
This is the whole UserPatientAdd class: https://ideone.com/clUSa3
How can I solve this problem?
You need to set the UserPatient using something like this
In your SharedResources class, create a new method:
public void setUserPatient(UserPatient user) {
userPatient = user;
}
Then in your UserPatientAdd class set the new object:
UserPatient userPatient = new UserPatient (birth, name, bloodType, bloodPressure, cbpm, vacinesTaken, vacinesToBeTaken,
allergies,weight, height, surgeries, desease);
SharedResources.getInstance().setUserPatient(userPatient);
Done
Whenever I run my code, the inv.txt file changes from having 25 lines of the character 1 to nothing, could someone tell me what I'm doing wrong?
PS the main class includes inventory.addItem();
public class inventory {
File inventory = new File("Resources/inv.txt");
File db = new File("Resources/db.txt");
FileWriter write;
StringBuilder writethis;
public void addItem(int item, int slot){
int i;
Scanner scan = null;
try {
scan = new Scanner(inventory);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
write = new FileWriter(inventory);
} catch (IOException e) {
e.printStackTrace();
}
for(i = 1; i < slot; i++)writethis.append(scan.nextLine());
System.out.println(writethis.toString());
}
}
Use write = new FileWriter(inventory, true);
It will append data to existing file. See the documentation on FileWriter Constructor for further details.
I am wondering why I get this warning with the new eclipse Juno despite I think I correctly closed everything. Could you please tell me why I get this warning in the following piece of code?
public static boolean copyFile(String fileSource, String fileDestination)
{
try
{
// Create channel on the source (the line below generates a warning unassigned closeable value)
FileChannel srcChannel = new FileInputStream(fileSource).getChannel();
// Create channel on the destination (the line below generates a warning unassigned closeable value)
FileChannel dstChannel = new FileOutputStream(fileDestination).getChannel();
// Copy file contents from source to destination
dstChannel.transferFrom(srcChannel, 0, srcChannel.size());
// Close the channels
srcChannel.close();
dstChannel.close();
return true;
}
catch (IOException e)
{
return false;
}
}
IF you're running on Java 7, you can use the new try-with-resources blocks like so, and your streams will be automatically closed:
public static boolean copyFile(String fileSource, String fileDestination)
{
try(
FileInputStream srcStream = new FileInputStream(fileSource);
FileOutputStream dstStream = new FileOutputStream(fileDestination) )
{
dstStream.getChannel().transferFrom(srcStream.getChannel(), 0, srcStream.getChannel().size());
return true;
}
catch (IOException e)
{
return false;
}
}
You won't need to explicitly close the underlying channels. However if you're not using Java 7, you should write the code in a cumbersome old way, with finally blocks:
public static boolean copyFile(String fileSource, String fileDestination)
{
FileInputStream srcStream=null;
FileOutputStream dstStream=null;
try {
srcStream = new FileInputStream(fileSource);
dstStream = new FileOutputStream(fileDestination)
dstStream.getChannel().transferFrom(srcStream.getChannel(), 0, srcStream.getChannel().size());
return true;
}
catch (IOException e)
{
return false;
} finally {
try { srcStream.close(); } catch (Exception e) {}
try { dstStream.close(); } catch (Exception e) {}
}
}
See how much better the Java 7 version is :)
You should always close in finally because if an exception rise, you won't close the resources.
FileChannel srcChannel = null
try {
srcChannel = xxx;
} finally {
if (srcChannel != null) {
srcChannel.close();
}
}
Note: even if you put a return in the catch block, the finally block will be done.
eclipse is warning you about the FileInputStream and FileOutputStream that you can no longer reference.
I am trying to do some kind of serialization where I can directly read and write objects from file.
To start of I just tried to write a character to file and tried to read it. This keeps giving me EOF exception always.
I am trying it on a Android device. Here is my code:
public class TestAppActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
WriteToFile();
Load();
} catch (Exception e) {
e.printStackTrace();
}
}
public void Load () throws IOException
{
InputStream fis;
ObjectInputStream in = null;
try {
fis = new FileInputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
in = new ObjectInputStream(fis);
char temp = in.readChar();
} catch (IOException e) {
e.printStackTrace();
} finally {
in.close();
}
}
public static void WriteToFile() throws Exception {
try {
OutputStream file = new FileOutputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
ObjectOutput output = new ObjectOutputStream(file);
try {
output.writeChar('c');
} finally {
output.close();
}
} catch (IOException ex) {
throw ex;
}catch (Exception ex) {
throw ex;
}
}
}
In this case, EOFException means there is no more data to be read, which (again in this case) can only mean that the file is empty.
Why are you using ObjectInput/OutputStreams but only writing chars? You'd be better off with DataInput/OutputStreams for that usage.
Also there is no point in catching exceptions only to rethrow them.
Also there is no point in reading a char from a file unless you are going to put it somewhere other than in a local variable that isn't even returned by the method.
I have imported this code in my sample project with following change.
i replaced "\\test2.ser"with "/test2.ser" and it worked. please try this.