switch usage in Java, programming rule/grammar

fhleung · 07-05-2013, 11:53 PM

switch logic is available almost all types of programming language.

Code:

int type;
type = System.in.read();
switch(type) {


case 11:
switch(type2) {
case 21:
variable = "case 21";
case 22:
variable = "case 22";
break;


case 12:
variable = "case 2";
break;
}

My question is:

I would like to have DOUBLE switch(), I mean like second switch() inside each case like above code. Could you please show me a brief implementation/example ?

in the switch(type) , inside the bracket, what type of this variable can be?

Thank you.

psionl0 · 07-06-2013, 01:18 AM

Do you mean something like this?

Code:

switch(type) {

   case 11: 
      switch(type2) {
         case 21:
            variable = "case 21";
            break;
         case 22:
            variable = "case 22";
            break;
      }
      break;

   case 12:
      variable = "case 2";
      break;
}

type could be char, short, int, long or enumerated.

fhleung · 07-06-2013, 08:57 PM

Thank you for reply. The type variable in the switch(type) is INPUT
and the OUTPUT would be, to the console screen. So...

INPUT = switch(type) switch(type2)
OUTPUT = System.out.print(variable);

for example code to test, I have System.in.read(); to get the input from keyboard
but it's NOT work. Any idea?

Code:

type = System.in.read();

psionl0 · 07-06-2013, 09:24 PM

Quote:

Originally Posted by fhleung

I have System.in.read(); to get the input from keyboard
but it's NOT work. Any idea?

You have to press the Enter key to get characters into the input buffer.

The standard Java console is not designed for inputting individual characters.

fhleung · 07-06-2013, 09:42 PM

Code:

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

public class  {

public static void main(String[] args) {
		int type;
		int type2 = 21;
		String variable = null;

InputStreamReader i = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(i);

				type = br.read();
				//type = System.in.read();

				switch (type) {
				
				case 11:
					switch(type2) {
				         case 21:
				            variable = "case 21";
 				            break;
				         case 22:
				            variable = "case 22";
				            break;
				        }
					break;
				case 12:
					variable = "case 2";
					break;
				default:
					variable = "case 3";
					break;
				}

				System.out.print(variable);

}
}

"You have to press the Enter key to get characters into the input buffer."
Enter pressED after something on keyboard keyin

Please run the above code. It always output default. Any idea?

psionl0 · 07-06-2013, 11:51 PM

Try type = System.in.read();

Bear in mind that codes 11 and 12 are control characters which won't be in your input stream so you will always get the default case.

fhleung · 07-08-2013, 01:25 AM

"Bear in mind that codes 11 and 12 are control characters which won't be in your input stream"

Wait... I don't get what you mean.
11 and 12 are int type wasn't it? What I want was type number 11, 12 on the keyboard.

pan64 · 07-08-2013, 01:40 AM

as integers 11 and 12 mean the 11th and 12th ascii chars, and they are both control characters, cannot be entered.
as strings "11" and "12" can be entered but cannot be handled by System.in.read() (because it handles only single keypresses/chars)
see here: http://www.abbeyworkshop.com/howto/j...ine/index.html

devnull10 · 07-08-2013, 06:28 AM

And also I would suggest not to use a variable name "type".

fhleung · 07-09-2013, 06:43 PM

I just don't get what you mean

I made changes to the above code using InputStreamReader and BufferedReader. Please run the above code.

"type could be char, short, int, long or enumerated."
Please show me a similar code example that the INPUT type is int

psionl0 · 07-10-2013, 05:25 AM

Try a simpler interactive language (like BASIC) where you can quickly learn the difference between integers, bytes, characters and strings.

THEN go back to a professional language like Java.

fhleung · 07-10-2013, 05:47 AM

"type could be char, short, int, long or enumerated."
Please show me a similar code example that the INPUT type is int

pan64 · 07-10-2013, 07:14 AM

you can find some examples here: http://www.roseindia.net/tutorialsea...System.in.read

psionl0 · 07-10-2013, 07:46 AM

Quote:

Originally Posted by fhleung

"type could be char, short, int, long or enumerated."
Please show me a similar code example that the INPUT type is int

Quote:

Originally Posted by fhleung

What I want was type number 11, 12 on the keyboard.

It sounds like you want to input character strings like "11", "12" etc and then convert them to integers.

I'm not sure that Java's System.in class has methods that do this directly. However, the java.lang.Integer class has methods which will convert the input strings to integers.

Soderlund · 07-10-2013, 02:22 PM

You want to read integers from the keyboard, right? Any reason not to use the Scanner class?

Code:

Scanner scan = new Scanner(System.in);
while (!scan.hasNextInt())
{
    scan.next(); // Discard non-integer.
}
switch (scan.nextInt())
{
    ...
}