return from void method..

[swati bannore]

One more question which returns from void method..

public class Test045
{
int Method1(int i) { return 1; } //1
//void Method2(int i) { return i + 1; } //2
int Method3(int i) { return i + 1; } //3
void Method4(int i) { return; } //4
public static void main(String args[]){
Test045 demo = new Test045();
System.out.println(demo.Method1(1));
//System.out.println(demo.Method2(2));
System.out.println(demo.Method3(3));
// WHy does it give error,Can not convert int to char[].........?
System.out.println(demo.Method4(2));
}
}

Thanx

[Bindesh Vijayan]

Swati, I don't get the same error.The only error I get is regarding the last call that is bcoz of void type return declared.
System.out.println(demo.Method4(2));
Thanks.
[This message has been edited by Bindesh Vijayan (edited September 08, 2001).]

[Ragu Sivaraman]

Bindesh,
I dont seem to get any errors on both the cases
1. int method(int i) {
return i+1;
}
+ has both operands as integers
2. void method4(int a) {
return;
}
void can have return
just that it cant return any value thats all
Let me know
Thankx

[swati bannore]

Hi,
Let me make it very simple and clear.

public class Test045
{
void Method4(int i) { return; } //4
public static void main(String args[]){
Test045 demo = new Test045();
System.out.println(demo.Method4(2));
// When I call a method with integer literal,it gives error as ,Can not convert void to char[].........?
}
}

Hope it will be clear now,and u cld help me.
Thanx

[Ragu Sivaraman]

Originally posted by swati bannore:
Hi,
Let me make it very simple and clear.
Hope it will be clear now,and u cld help me.
Thanx

swati,
When i try to compile this code , yes i do get error
But the error message is different
C:\SCJP\Vest.java:8: 'void' type not allowed here
System.out.println(demo.Method4(2));
^
1 error
Tool completed with exit code 1
Its becoz, there is no signature in System class that can
accept void as a parameter
From JDK doc:
public static final PrintStream out
The "standard" output stream. This stream is already open and ready to accept output data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.
For simple stand-alone Java applications, a typical way to write a line of output data is:
System.out.println(data)
But I am sorry swati, I dont know why and how you getting that error? Let me know if you discover it
Thankx
Ragu

[Bindesh Vijayan]

I too get the same error Swati,as Raghu reports.
Thanks

[swati bannore]

Hi,
I am using JDK1.2.2 , cld the error differ cause of that..?
Anyways..Main doubt is when you have return statement in void method.WHat's the ponit in having return ststamenet ,if compiler is to give error when you call them.
Thanx anyways

[Bindesh Vijayan]

Swati I think you mistook the error.What I think, the problem is not bcoz you have return a statement, but the problem is that you are trying to print the value returned from the method in println statement.
System.out.println takes a valid arg but since your method is not returning any thing,bcoz simply saying return in any function means to return from that position.This means to say that if you havae a return statement in between the function then after reading that return statement it will return from the function without executing the other statements below the line.
This is the use of return .Here is a small example

public void ret()
{
if(true)
{
System.out.println("Swati1");
return;
}
else
{
System.out.println("Swati2");//this will not be printed
}
}

Thanks.
[This message has been edited by Bindesh Vijayan (edited September 09, 2001).]

[swati bannore]

Thanx a Bunch Bindesh.....

[Bindesh Vijayan]

I am sorry Swati I was wrong there.You know it happens sometime .Actually I was wrong here

This means to say that if you havae a return statement in between the function then after reading that return statement it will return from the function without executing the other statements below the line.

This statement is true regarding C but not in Java.Iam sorry again.I was too quick.
But Iam cent percent correct with my logic behind the error.
As too you real question,
WHat's the ponit in having return statemnt

I'll try to find an answer for it or may be some one will answer it, before I do.

[Guoqiao Sun]

Hi, swati, I think the problem is that Java does not provide the following method:
<code>
System.out.println(void);
</code>
The following code gives compile error:

public class T050 
{    
    public static void main(String args[])
    {
        System.out.println(method());
    }
    
    public static void method()
    {
        return;
    }    
}

error is:

<font color=red>
T050.java [9:1] No method found matching println(void)
        System.out.println(method());
                   ^
1 error

Originally posted by swati bannore:

Regards,

------------------
Guoqiao Sun
Sun Certified Programmer for Java™ 2 Platform
try my mock exam¹² at my homepage.

[Jin Qin]

Test049
The answer should be 12 instead of 18. Take note of the seek(4)
before r.writeLong(5).
BTW, Sun, I gained a lot from your contribution. Keep the excellent work ! Appreciated.
Regards,
Jin

[Valentin Crettaz]

I made the same error jin, but read carefully the question. It says how many bytes are written and not how many byte are actually contained in the file !! So the answer is correct (18)
Val

[Guoqiao Sun]

Thank you Valentin for your nice feedback.
Good luck to your SCJP tour!

------------------
Guoqiao Sun
Sun Certified Programmer for Java™ 2 Platform
try my mock exam¹²³ at my homepage.