5
public class Test {

/**
 * @param args
 */

// 1st way
public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println("Test....!!!!!");
}

// 2nd way
static{
System.out.println("Test....!!!!!");
System.exit(1);
}

// 3rd way
private static int i = m1();
public static int m1(){
    System.out.println("Test...!!!!");
    System.exit(0);
    return 0;
}

Other than this, can we print message any other way.

David Ansermot
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Ravi
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  • I think from Java 7 onwards your second approach will not print (and we call it is static block, not method) – kosa Aug 11 '13 at 11:34
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    @Nambari what makes you say that?! – Boris the Spider Aug 11 '13 at 11:35
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    The question is not clear. Do you mean without *ever* using `main()`? #2 and #3 do not work unless *some* `main()` method was ever called that loaded a class containing such declarations. – Sean Owen Aug 11 '13 at 11:36
  • @BoristheSpider: There was interesting question regarding System.out in static block few days ago (assuming no main method, only static block inside your program and try to run it. Less than Java7, it runs). – kosa Aug 11 '13 at 11:40
  • Dear Sean Owen, What i was trying to ask is, Is there any way to print a simple message on console. Without using static method, static variable, static block and main(). – Ravi Aug 12 '13 at 04:06

1 Answers1

7

Of course you can, from a class constructor, method or instance block for instance.

However if you're talking about launching a simple program with the command line (e.g. java -jar myProgram), you'll still need to instantiate the class where the instance code printing to console resides, in a main method.

For instance, with given class Foo:

public class Foo {
    // Initializer block Starts
    { 
        System.out.println("Foo instance statement");
    }
    // Initializer block Ends

    public Foo() {
        System.out.println("Foo ctor");
    }
    public void doSomething() {
        System.out.println("something done from this Foo");
    }
}

... now from the main method of your Main class: 

public static void main(String[] args) {
    new Foo().doSomething();
}

Output:

Foo instance statement
Foo ctor
something done from this Foo
Algorithmist
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Mena
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  • Can you please throw some more light on How System.out.println("Foo instance statement"); is working.Will it be executed every time we create objects of this class? – Algorithmist Aug 11 '13 at 11:59
  • @Algorithmist exacly. Every new instance of `Foo`, the instance statement is executed. – Mena Aug 11 '13 at 12:01
  • But how it is working,it is neither part of a constructor or anything else,it is just a simple block. – Algorithmist Aug 11 '13 at 12:03
  • @Algorithmist the [documentation](http://docs.oracle.com/javase/tutorial/java/javaOO/initial.html) tells it better than I can. The explanation is at the bottom of the page, with the instance member initialization section. – Mena Aug 11 '13 at 12:09
  • @Mena does `new Foo()` use `Foo.class.newInstance()`? or some other reflection based method? – boxed__l Aug 11 '13 at 12:37