What does void do in java

Question

The return type   the data type of the value returned by the method  or void if the method does not return a value    http   download oracle com javase tutorial java javaOO methods html  Okay  then   Here is my question   public class EnumTest       Day day       public EnumTest Day day            this day   day             public void tellItLikeItIs             switch  day                case MONDAY  System out println  Mondays are bad                              break               case FRIDAY  System out println  Fridays are better                              break               case SATURDAY              case SUNDAY  System out println  Weekends are best                              break               default      System out println  Midweek days are so-so                              break                       public static void main String   args            EnumTest firstDay   new EnumTest Day MONDAY           firstDay tellItLikeItIs            EnumTest thirdDay   new EnumTest Day WEDNESDAY           thirdDay tellItLikeItIs            EnumTest fifthDay   new EnumTest Day FRIDAY           fifthDay tellItLikeItIs            EnumTest sixthDay   new EnumTest Day SATURDAY           sixthDay tellItLikeItIs            EnumTest seventhDay   new EnumTest Day SUNDAY           seventhDay tellItLikeItIs                http   download oracle com javase tutorial java javaOO enum html  The above code does not work without void   Exception in thread  main  java lang Error  Unresolved compilation problems       The method tellItLikeItIs   is undefined for the type EnumTest   What did I miss out  Why is there a void in there  And it does return a string

User · Accepted Answer

The reason the code will not work without void is because the System.out.println(String string) method returns nothing and just prints the supplied arguments to the standard out terminal, which is the computer monitor in most cases. When a method returns "nothing" you have to specify that by putting the void keyword in its signature.

You can see the documentation of the System.out.println here:

http://download.oracle.com/javase/6/docs/api/java/io/PrintStream.html#println%28java.lang.String%29

To press the issue further, println is a classic example of a method which is performing computation as a "side effect."

User · Answer

You mean the tellItLikeItIs method  Yes  you have to specify void to specify that the method doesn t return anything  All methods have to have a return type specified  even if it s void   It certainly doesn t return a string - look  there are no return statements anywhere  It s not really clear why you think it is returning a string  It s printing strings to the console  but that s not the same thing as returning one from the method

User · Answer

Void  the type modifier void states that the main method does not return any value  All parameters to a method are declared inside a prior of parenthesis  Here  String args    declares a parameter named args which contains an array of objects of the class type string

User · Answer

Void doesn t return anything  it tells the compiler the method doesn t have a return value

User · Answer

void means it returns nothing   It does not return a string  you write a string to System out but you re not returning one   You must specify what a method returns  even if you re just saying that it returns nothing     Technically speaking they could have designed the language such that if you don t write a return type then it s assumed to return nothing  however making you explicitly write out void helps to ensure that the lack of a returned value is intentional and not accidental

User · Answer

When the return type is void  your method doesn t return anything     Look again at your code  There s no return in that method   You print to the console and exit

[java] What does void do in java?

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Examples related to void