User input

[maydoncillo]

hi,
How will i check if the user input is valid digit/numbers..?
How will i do it in java..?

[heat84]

One soultion may be to use the Character class and then checking if the characters in a string are digits or not .

Read the java docs , I am sure you will get the information you need.

[JosAH]

hi,
How will i check if the user input is valid digit/numbers..?
How will i do it in java..?

Note that e.g. de Integer and Double class can convert a String to the type they
wrap. If the String doesn't represent a valid wrapped type (int or double in this
example) an NumberFormatExc eption is thrown.

kind regards,

Jos

[BigDaddyLH]

Demo: This reads from System.in, a line at a time and attempts to parse the line as an int.
[CODE=Java]import java.io.*;

public class NumberInputExam ple {
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(
new InputStreamRead er(System.in));
String line;
while((line = in.readLine()) != null) {
try {
int n = Integer.parseIn t(line);
System.out.form at("(%1$d)*(%1$ d)=%2$d%n", n, n*n);
} catch (NumberFormatEx ception e) {
System.out.form at("'%s' cannot be parsed%n", line);
}
}
}
}[/CODE]