Cannot convert from void to String

Question

Driver class:

String world = methods.printHelloWorld("Hello, world!");
{
    System.out.println(world);
}

method class:

public void printHelloWorld(String world)
{
    world = "Hello, world!";
}

Prompt: (part of a larger project)

void printHelloWorld()

Parameters: none

Return nothing. Directly prints to System.out the String "Hello, world!"

I'm getting the error that I cannot convert from void to String. I can't use a return in my method class. I know I can change public void printHelloWorld(String world) to public String printHelloWorld(String world), but that isn't what my teacher wants us to do. (I tried those already)

Why don't you just call the method without assigning it to anything? — Sotirios Delimanolis, Oct 09 '13 at 20:17
Hint: Pass by Value vs Pass by Reference. http://stackoverflow.com/questions/373419/whats-the-difference-between-passing-by-reference-vs-passing-by-value — Randy, Oct 09 '13 at 20:19

Ted Hopp · Answer 1 · 2013-10-09T20:26:05.857

You can't convert to a String because there's nothing to convert. A return type of void means "does not return a value".

Also, you can assign values inside a method to a formal parameter all you want (unless it is declared final) and it won't change the value of the actual parameter used in the call to the method.

Perhaps you were trying to do this:

String world = "Hello, world!";
methods.printHelloWorld(world);

and

public void printHelloWorld(String world)
{
    System.out.println(world);
}

score 1 · Answer 2 · answered Oct 09 '13 at 20:18

I know I can change public void printHelloWorld(String world) to public String printHelloWorld(String world), but that isn't what my teacher wants us to do. (I tried those already)

Then you can print inside the method itself. Something like:

public void printHelloWorld(String world)
{
    System.out.println(world);
}

M. Abbas · Accepted Answer · 2013-10-09T20:24:25.033

1

The exception is very clear: You cannot convert from void to String.

This is how you can achieve what you are trying to do:

public void printHelloWorld(String world) {
    System.out.println(world);
}

Then

methods.printHelloWorld("Hello, world!");

edited Oct 09 '13 at 20:24

answered Oct 09 '13 at 20:18

M. Abbas

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A side note: It's not an exception, it's a compile-time error :) – Simon Forsberg Oct 14 '13 at 00:11

score 0 · Answer 4 · edited Oct 09 '13 at 20:27

0

public void printHelloWorld(String world)
{
    world = "Hello, world!";
    System.out.println(world);
}

edited Oct 09 '13 at 20:27

Sachin Thapa

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answered Oct 09 '13 at 20:20

Victor

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Please include an explanation along with your code snippet. – bedwyr Oct 09 '13 at 20:22

score 0 · Answer 5 · answered Oct 09 '13 at 20:22

0

in method Class have

  public static String world = "Hello, world!";

in driver class

 String world1 = methods.world;
 System.out.println(world1);

answered Oct 09 '13 at 20:22

Kaushik Sivakumar

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9

score 0 · Answer 6 · answered Oct 09 '13 at 20:23

0

Your method should return String

public String printHelloWorld(String world)
{
    world = "Hello, world!";
    return world;
}

or Simply

public String printHelloWorld(String world)
{
    return "Hello, world!";
}

Cheers !!

answered Oct 09 '13 at 20:23

Sachin Thapa

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Cannot convert from void to String

6 Answers6