How do I get the program to ask questions after input?

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I've tried, mainly for the purpose of this question of making a simple "calculator" type program. When it runs the last 3 sentences will print out without letting the user enter anything. How do I make the program only ask a question after input?
Thanks for any help in advance.

What I have tried:

Java

import java.util.Scanner;
public class hello1{
public static void main(String[]args)
{

 Scanner scan = new Scanner(System.in);
 String s1 ="";
 int num1=0;
 int square=0;

    do
    {
    	System.out.println("Please enter a number between 1 and 20");
    	num1 = scan.nextInt();
    	System.out.println("Do you want to square this number?");
    	String s2 = scan.nextLine();
    	if(s2.equalsIgnoreCase("Yes"))
    	{
    		square = num1*num1;
    		System.out.println("The square is " + square);
    	}
    	else
    	{
    		System.out.println("No square");
    	}

        System.out.println("Do you want to continue? Y/N");//Print
        s1 =scan.nextLine();//Read

    }

    while(s1.equalsIgnoreCase("Y"));
}
}

Posted 4-Nov-16 11:20am

Member 12833355

Updated 4-Nov-16 23:30pm

v2

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2 solutions

Solution 1

With the debugger, you will see exactly what num1, s2 and s1 contain at runtime.

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
When the code don't do what is expected, you are close to a bug.

Posted 4-Nov-16 13:27pm

Patrice T

Updated 5-Nov-16 0:13am

v2

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Richard MacCutchan · Accepted Answer · 2016-11-04T23:30:00

Solution 2

Just add the extra line in your code as shown:

Java

System.out.println("Please enter a number between 1 and 20");
num1 = scan.nextInt();
scan.nextLine(); // add this line to consume the newline character
System.out.println("Do you want to square this number?");

Posted 4-Nov-16 23:30pm

Richard MacCutchan

Comments

Patrice T 5-Nov-16 6:26am

I am afraid the solution can't be so simple !
The OP is already using scan.nextLine() in second and third input.
It don't match the problem description.

Richard MacCutchan 5-Nov-16 6:27am

Yes it is and it does.

Patrice T 5-Nov-16 6:37am

If adding a scan.nextLine() is the solution, the description should speak about a skip of second input.

Richard MacCutchan 5-Nov-16 6:42am

I tested my fix and it does what OP wants. If your test does not work then please provide the details.

Patrice T 5-Nov-16 6:54am

In this case, I suspect the problem description is wrong, that is why I suggest to debug the program to see what really happen.
I don't have Java to test it.

Richard MacCutchan 6-Nov-16 2:44am

It doesn't need debugging, it's a simple error. After calling scan.nextInt(); there is still, at the very least, an unconsumed newline in the input buffer. So the next call to scan.nextLine(); will read that, and not the input typed by the user.