[Java] reading file

[Umair_Ahmad_Khan]

i m tryin to learn java need little help

i have data in this format

46728 s 1000 2700

87324 c 1500 7689

79873 s 1000 800

89832 c 2000 3000

98322 c 1000 750

public void process() {  
		FileInputStream in;
		 DataInputStream input;
		int acc_no;
		char type;
		double min_bal;
		double curr_bal;


		  try{
			  in = new FileInputStream("Dat.txt");
			  input = new DataInputStream(in);
		  } catch (IOException e) 
		  {
			  System.out.print("Filen't exists");
			  System.exit(0);
		  }	  

		  try{			  
			  acc_no = input.readInt();
			  type = input.readChar();
			  min_bal = input.readDouble();
			  curr_bal = input.readDouble();
			  System.out.print('\n			  System.out.print(acc_no);
			  System.out.print('\t			  System.out.print(type);
			  System.out.print('\t			  System.out.print(min_bal);
			  System.out.print('\t			  System.out.print(curr_bal);  
		  }catch(EOFException eofex)
		  {
			  try{
				  input.close();
			  }catch (IOException ioe)
			  {
				  System.out.print("Fileclosed");
			  }
		  }
		  catch(IOException e)
		  {
			  System.out.print("Errorng reading file DATA.txt");
		  }

I just want to read and print the data :( but this giving me wrong output. and if i use input.readline and store whole line in string then it it prints right data i want data in int,char,double,double variables. i wil read data in whileloop line by line but atleast it shuld print first line right :(

[XgD]

Are the filenames correct? At the top you have Dat.txt, at the bottom you have DATA.txt

XgD

[Umair_Ahmad_Khan]

oh yes actually file opening ok everyfing else is ok .. only problem is i don't know how to get data in variables.

[kjordan2001]

Assuming you're using Java 1.5, you can use the Scanner class.

Scanner input = new Scanner(in);

int x = input.nextInt();

char c = input.next().charAt(0);

double y = input.nextDouble();

double z = input.nextDouble();

[davemania]

Read line into a string i.e input

String[] line = input.split(" ");

this will give you the columns into a string array and you can cast each element of the array into whatever variable you want

[JamesCherrill]

I think your problem is that the various read* methods simply take the next n bytes from the Stream. They don't automatically skip the blanks that you have between your data items.

[Umair_Ahmad_Khan]

for scanner object what i need to 'import'

using search i found java.util.*; but still givin error

[davemania]

Scanner is found in java.util.Scanner

What is the exact error you're getting

[Umair_Ahmad_Khan]

Ok I have done every thing :) everything working fine. just one problem

I made it using Jbuilder. so if i run it in Jbuilder its running fine no error and giving required results but if i go to command prompt and type java bank.java

it gives error

Exception in thread "main" java.lang.NoClassDefFoundError: E:\WORK\java\

bank/java

what is this exceptiong :/ it only appear if i run using java command in windows

[JamesCherrill]

  Umair_Ahmad_Khan said:

Ok I have done every thing :) everything working fine. just one problem

I made it using Jbuilder. so if i run it in Jbuilder its running fine no error and giving required results but if i go to command prompt and type java bank.java

it gives error

Exception in thread "main" java.lang.NoClassDefFoundError: E:\WORK\java\

bank/java

what is this exceptiong :/ it only appear if i run using java command in windows

.java files are your source program. At run time you need the .class file.

Your best approach is to use JBuilder to make an executable .jar containing all your classes that you need for your app (see the JBuilder help & examples for step-by-step instructions) then run it with

java -jar myAppName.jar or by simply double-clicking it

Edited May 13, 2006 by JamesCherrill