reading a double

[Russell Wade]

Real beginner here. Started to experiment with some code. Originally had the values hardcoded into the program. Then I wanted to read the values in through the console. The following code compiles but does give the desired results.

public static void main(String [] args) throws IOException{
DataInputStream in = new DataInputStream(
System.in);
System.out.println("Enter beginning balance:");
ip_value = in.readDouble();
System.out.println(ip_value);
TestAccount account = new TestAccount();
NumberFormat dollarformat = NumberFormat.getCurrencyInstance();
System.out.println("beginning balance = " + dollarformat.format(ip_value));
2000 was entered.
results:
6.004549348750547E-67
beginning balance = $0.00

[Wayne L Johnson]

If you look at the Java API for java.io.DataInputStream you'll see that it reads native java data as bytes. The "readDouble()" method indicates that it'll read the next eight bytes and interpret it as a double (based on the IEEE 754 spec). This is not what you want.
You want to read in the characters you type and convert that to a double. try this:

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter beginning balance:");
String ip_str = in.readLine();
double ip_value = Double.parseDouble(ip_str);
System.out.println(ip_value);

And as a defensive measure, you'll probably want to put the "parseDouble()" call inside of a try/catch block.
[ March 08, 2004: Message edited by: Wayne L Johnson ]