structure equivalant in java

Nagy Vilmos

Make your class serialisable and write it to a binary buffer. Sorted.

Panic, Chaos, Destruction. My work here is done. or "Drink. Get drunk. Fall over." - P O'H

trioum

can you send me the piece of code for writing class content to the file

Trioum

TorstenH

what kind of file? do you want to have an output to some textfile or did you get stuck on how to assume values to the fields? regards Torsten

I never finish anyth...

Nagy Vilmos

trioum wrote:

can you send me the piece of code for writing class content to the file

0. Define the class as implements Serializable:

class Foo implements Serializable
{
private int bar;
// stuff

// other stuff
}

1. Write it to a binary buffer:

Foo foo = new Foo(42);

try
{
java.io.ObjectOutputStream os =
new java.io.ObjectOutputStream(
new java.io.FileOutputStream("foobar.dat"));
os.writeObject(foo);
} catch (java.io.IOException e)
{
e.printStackTrace();
} finaly
{
os.close();
}

That's hard how?

Panic, Chaos, Destruction. My work here is done. or "Drink. Get drunk. Fall over." - P O'H

David Skelly

That won't compile. os is out of scope in the finally block.

trioum

wont compile

Trioum

trioum

there is difference i getting when writing using c and java following lines shows the difference when I use the c code struct _Foo { int one; int two; char buffer[50]; } ; struct _Foo foo; memset(&foo,'0/',sizeof(_Foo)); foo.one = 2; foo.two = 3; strcpy(foo.buffer,"my name is trioum"); FILE *fp; fp = fopen("cfile.txt","wb"); if(fp) { fwrite(&foo,sizeof(struct _Foo),1,fp); fclose(fp); } result in the file I get my name is trioum ////////////////////////////////// but when I write the same code in java public static class _Foo implements Serializable { public int one; public int two; public String buffer = new String(new char[50]); } ObjectOutputStream outputStream = null; try { outputStream = new ObjectOutputStream(new FileOutputStream("javafile.txt")); _Foo Foo = new _Foo(); Foo.one = 2; Foo.two = 3; Foo.buffer = "my name is trioum"; outputStream.writeObject(Foo); } catch (FileNotFoundException ex) { ex.printStackTrace(); } catch (IOException ex) { ex.printStackTrace(); } I get the result in javafile.txt ¬í sr Main$_FooDpÕGTÂ¯_ I oneI twoL buffert Ljava/lang/String;xp t my name is trioum But I want the result as seen in cfile.txt by c code How can I solve the problem

Trioum

David Skelly

That's because you are serializing the whole Foo object, which is not what you want. I'm not going to write the whole thing for you but I think I would make Foo look something like this:

public class Foo {

public char one;
public char two;
public String buffer;
... etc ...

public String toExternalForm() {
StringBuilder sb = new StringBuilder();
sb.append(one);
sb.append(two);
sb.append(buffer);
... etc ...
return sb.toString();
}

}

Then to use it:

foo.one = 2;
foo.two = 3;
foo.buffer = "something";
bw = new BufferedWriter(...etc...);
bw.write(foo.toExternalForm());
bw.flush();

That's basically it, you can look up BufferedWriter and whatever else you need and you might want to be a bit more intelligent about handling nulls. (I am using char instead of int in the class Foo because if we use int then StringBuilder would give us 23something which is not what you want, if I have understood correctly.)

trioum

check it again it is producing wrong result

Trioum

David Crow

Why not use a class?

class xyz
{
public int data;
public string buffer;
};

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