The method println(double) in the type PrintStream

问题:

Here is the code:

import java.util.Scanner;

public class MoviePrices {
    public static void main(String[] args) {
        Scanner user = new Scanner(System.in);
        double adult = 10.50;
        double child = 7.50;
        System.out.println("How many adult tickets?");
        int fnum = user.nextInt();

        double aprice = fnum * adult;
        System.out.println("The cost of your movie tickets before is ", aprice);

    }
}

I am very new to coding and this is a project of mine for school. I am trying to print the variable aprice within that string but I am getting the error in the heading.

回答1:

Instead of this:

System.out.println("The cost of your movie tickets before is ", aprice);

Do this:

System.out.println("The cost of your movie tickets before is " + aprice);

This is called "concatenation". Read this Java trail for more info.

Edit: You could also use formatting via PrintStream.printf. For example:

double aprice = 4.0 / 3.0;
System.out.printf("The cost of your movie tickets before is %f\n", aprice);

Prints:

The cost of your movie tickets before is 1.333333

You could even do something like this:

double aprice = 4.0 / 3.0;
System.out.printf("The cost of your movie tickets before is $%.2f\n", aprice);

This will print:

The cost of your movie tickets before is $1.33

The %.2f can be read as "format (the %) as a number (the f) with 2 decimal places (the .2)." The $ in front of the % is just for show, btw, it's not part of the format string other than saying "put a $ here". You can find the formatting specs in the Formatter javadocs.

回答2:

you are looking for

System.out.println("The cost of your movie tickets before is " + aprice);

+ concatenates Strings. , separates method parameters.

回答3:

Try this one

System.out.println("The cost of your movie tickets before is " + aprice);

And you can also do that:

System.out.printf("The cost of your movie tickets before is %f\n", aprice);

回答4:

This will help:

System.out.println("The cost of your movie tickets before is " + aprice);

The reason is that if you put in a coma, you are sending two different parameters. If you use the line above, you add the double onto your string, and then it sends the parameters as a String rather than a String and a double.

回答5:

It occurs when you use , instead of + i.e:

use this one:

System.out.println ("x value" +x);

instead of

System.out.println ("x value", +x);