How can you run a Java program without main method

Question

Possible Duplicate    Printing message on Console without using main   method       Can someone suggest how can a JAVA program run without writing a main method    For eg   System out println  Main not required to print this      How can the above line be printed on console without using the public static void main String arg    in the class

User · Answer

Applets from what I remember do not need a main method  though I am not sure they are technically a program

User · Answer

Up to and including Java 6 it was possible to do this using the Static Initialization Block as was pointed out in the question Printing message on Console without using main   method  For instance using the following code   public class Foo       static            System out println  Message             System exit 0              The System exit 0  lets the program exit before the JVM is looking for the main method  otherwise the following error will be thrown      Exception in thread  main  java lang NoSuchMethodError  main   In Java 7  however  this does not work anymore  even though it compiles  the following error will appear when you try to execute it      The program compiled successfully  but main class was not found    Main class should contain method  public static void main  String   args     Here an alternative is to write your own launcher  this way you can define entry points as you want   In the article JVM Launcher you will find the necessary information to get started      This article explains how can we create a Java Virtual Machine   Launcher  like java exe or javaw exe   It explores how the Java   Virtual Machine launches a Java application  It gives you more ideas   on the JDK or JRE you are using  This launcher is very useful in   Cygwin  Linux emulator  with Java Native Interface  This article   assumes a basic understanding of JNI

User · Answer

Up until JDK6  you could use a static initializer block to print the message  This way  as soon as your class is loaded the message will be printed  The trick then becomes using another program to load your class   public class Hello     static       System out println  Hello  World             Of course  you can run the program as java Hello and you will see the message  however  the command will also fail with a message stating      Exception in thread  main  java lang NoSuchMethodError  main    Edit  as noted by others  you can avoid the NoSuchmethodError by simply calling System exit 0  immediately after printing the message   As of JDK6 onward  you no longer see the message from the static initializer block  details here

User · Answer

public class X   static     System out println  Main not required to print this      System exit 0        Run from the cmdline with java X

[java] How can you run a Java program without main method?

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