[SOLVED] Reading an input string?!

[sfe23]

I simply want to read an input string and output different messages depending on what I read.
the main problem is since my input is of type String then I cannot treat it as integers. How can I know if the user has input a number between 1 and 9?
Also if I encounter *, I want to output that is an operator.
My code outputs " it's an operand" no matter what I give it as an input!?
can someone help me please?


import java.io.*;
import java.lang.*;

class Test{

public static void main(String[] args) throws IOException
{
String input;
System.out.print("Enter input: ");

input = getString(); // read a string from kbd
for(int j=0; j<input.length(); j++) // for each char
{
char ch = input.charAt(j); // get it
// just so you know i have tried this as well
// int a = new Integer('ch').intValue();
// if (a >= 1 || a <= 9){

if (ch >= 1 || ch<= 9){
System.out.println("it's an opearnd");
}
else if (ch=='+' || ch == '-' || ch=='*' || ch=='/'){
System.out.println("it's a valid operator");
}
else
System.out.println("wrong input!");

}
}
public static String getString() throws IOException
{
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
String s = br.readLine();
return s;
}

} // end class

[CJSLMAN]

Wouldn't it be easier to use Character's method isDigit() or isLetter() to determine if it's a number or letter?

Character (Java Platform SE 6))
Character (Java Platform SE 6))

Luck,
CJSL

[sfe23]

[QUOTE=CJSLMAN;58248]Wouldn't it be easier to use Character's method isDigit() or isLetter() to determine if it's a number or letter?

Thanks, I didn't know that existed! I love Java :)

I get this error message though: cannot find symbol method isDigit(char)
even though I imported java.lang.Character;

import java.io.*;
//import java.lang.*;
import java.lang.Character; // in order to be able to use isDigit(char ch) method

class Test{

public static void main(String[] args) throws IOException
{
String input;
System.out.print("Enter input: ");

input = getString(); // read a string from kbd
for(int j=0; j<input.length(); j++) // for each char
{
char ch = input.charAt(j); // get it
// just so you know i have tried this as well
// int a = new Integer('ch').intValue();
// if (a >= 1 || a <= 9){

if (isDigit(ch)){
System.out.println("it's an opearnd");
}
else if (ch=='+' || ch == '-' || ch=='*' || ch=='/'){
System.out.println("it's a valid operator");
}
else
System.out.println("wrong input!");

}
}
public static String getString() throws IOException
{
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
String s = br.readLine();
return s;
}

} // end class

Does it have anything to do with the method being static?!

[Fubarable]

The isDigit(...) method is static, and you need to call it on the Character class:

if (Character.isDigit('3'))
{
  //...
}

[sfe23]

Fubarable,
I have tried that as well. in the above code if you replace
if (isDigit(ch)){
System.out.println("it's an opearnd");
}
with the following code:
if (Character.isDigit('ch')){
System.out.println("it's an opearnd");
}
I get 4 errors for that line that I added isDigit method!!
unclosed character literal
')' expected
unclosed character literal
';' expected

could you tell me why plz?

[Fubarable]

could you tell me why plz?

First you must tell us why you have (ch) in one example and ('ch') in another? Which is right (think on this before answering)?

[sfe23]

Well I changed it because i thought 'ch' is the right one which is NOT!
ch is the correct one.
and I can't believe I didn't even try it! I tried 100 other things but this!!
thanks for the hint Fubarable :)