Can we execute a java program without a main method

Question

According to my knowledge we cannot execute without a main method because when your running the java program  java Virtual machine look for the main method  if JVM could not find the main method it will show you run time error Exception in thread main could not find the main class   But I searched for many blogs and some of them are saying  yes it can be done through static blogs if there is a static block in a java program the class loader loads all static block before java gives call to main   method    Is it really possible and what will be the usability of these

User · Answer

Yes You can compile and execute without main method By using static block. But after static block executed (printed) you will get an error saying no main method found.

And Latest INFO --> YOU cant Do this with JAVA 7 version. IT will not execute.

{
    static
    {
        System.out.println("Hello World!");
        System.exit(0); // prevents “main method not found” error
    }
}

But this will not execute with JAVA 7 version.

User · Answer

Now - no    Prior to Java 7   Yes  sequence is as follows    jvm loads class executes static blocks looks for main method and invokes it   So  if there s code in a static block  it will be executed  But there s no point in doing that    How to test that   public final class Test       static           System out println  FOO              Then if you try to run the class  either form command line with java Test or with an IDE   the result is      FOO   java lang NoSuchMethodError  main

User · Answer

Since you tagged Java-ee as well - then YES it is possible  and in core java as well it is possible using static blocks and check this How can you run a Java program without main method  Edit  as already pointed out in other answers - it does not support from Java 7

User · Answer

You should also be able to accomplish a similar thing using the premain method of a Java agent      The manifest of the agent JAR file must contain the attribute Premain-Class  The value of this attribute is the name of the agent class  The agent class must implement a public static premain method similar in principle to the main application entry point  After the Java Virtual Machine  JVM  has initialized  each premain method will be called in the order the agents were specified  then the real application main method will be called  Each premain method must return in order for the startup sequence to proceed

[java] Can we execute a java program without a main() method?

Examples related to java