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In a traditional Java application, public static void main(String[] args) is the familiar method the Java launcher uses to start the program. Its parts describe who can call it, whether an object is needed, what it returns, and where command-line arguments go.
Why a Java program has a main method
A class-based Java application needs a starting point. When you launch a class, the Java runtime looks for a candidate main method on the initial class or interface and invokes it. That method can then call other methods to do the program’s work. Oracle’s beginner tutorial presents this familiar entry-point pattern in examples written for JDK 8: Java Tutorials: The Hello World! Application.
What each part of public static void main(String[] args) means
publicmakes the traditional method accessible to the launcher.staticmeans the launcher can call the method without first creating an instance of its class.voidmeans the method returns no value.mainis the conventional entry-point method name.String[] argsdeclares an array of strings that can hold command-line arguments.argsis only the parameter name; another valid name can be used.
The order of public and static can be reversed in the traditional declaration, although public static is the usual beginner-facing form. Oracle’s Java learning material explains these modifiers in launcher terms: The Java Virtual Machine.
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How command-line arguments reach the program
Arguments written after the class name in a launch command are passed to the method as strings in its array. For example, Oracle’s tutorial shows java MyApp arg1 arg2; the program can read those values from args to affect its behavior. If an argument contains spaces, quote it in the shell so it is passed as one argument.
What the Hello World print statement does
In System.out.println("Hello World!");, System.out is the standard-output stream and println writes the supplied text to it, followed by a line break. This is why the message appears in the terminal when you run the example.
Compile and run the conventional example
For a source file named Test.java that declares the corresponding class, the Java SE 26 Language Specification illustrates compiling and launching it like this:
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javac Test.java
java Test Hello, world.In the second command, Test is the class name; the text after it is supplied to the program as command-line arguments. The compiler and launcher commands are described in Java SE 26 Language Specification, Chapter 1.
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No. The declaration above remains the standard conventional form for a class-based beginner example, but it is not the only candidate entry-point form under current rules. The Java SE 26 Language Specification describes a broader set of candidate main methods, including methods with no parameter and instance methods, along with rules for selecting and invoking them: Java SE 26 Language Specification, Chapter 12.
Java SE 21 documented unnamed classes and instance main methods as a preview feature for that release, not as a description of today’s rules: JEP 445: Unnamed Classes and Instance Main Methods (Preview). Because entry-point rules vary by release, specify the target Java version when teaching or choosing a less familiar form. For portable beginner explanations, the traditional signature is the clearest place to start.
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