Java default constructor without initialization

Question

I have a class similar to the below one with all static methods. Hence the class was not initialized while used in other classes. I have to check a condition before invoking any static methods from this class. Even if i add a default constructor it will not get called. Could someone suggest ideas to have solution without instantiating this class in all of its usages? It need be a default constructor could be a simple other solution.

I need to check everytime the network connectivity before making the call. Static Initializer gets called only first time on load.

        public class ABCServerUtil {

        public static boolean checkServer() {...bla...bla...}


        }

I need some thing like below piece of code to be called and to be exit.

        public ABCServerUtil(){
        if(!isNetworkOnline())
        return;
        }

Hence the class was not initialized while used in other classes. - How do you know that it didn't get initialized? You don't have any static initializer blocks.. And please explain in detail what is happening and what isn't. :) — TheLostMind
– TheLostMind, Commented Mar 2, 2015 at 8:44
What you are describing is not an object and thus needs no constructor. You are defining static behavior and thus need to program it as such. — Jared
– Jared, Commented Mar 2, 2015 at 8:46

T.J. Crowder · Accepted Answer · 2015-03-02 08:44:26Z

2

If you need to check the condition every time one of the static methods is called, you don't have much choice but to do what you're doing: Call a method to do the check at the beginning of each of those methods.

If you only need to check the condition once when the class is initially loaded/initialized, you can use a static initializer:

public class ABCServerUtil {

    static {
        // Code here runs when the class is loaded
    }

    // ...
}

answered Mar 2, 2015 at 8:44

T.J. Crowder

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1 Comment

TheLostMind Over a year ago

If you need to check the condition every time one of the static methods is called, - He could use a Proxy to call all his methods here :P

Arun Kumar · Accepted Answer · 2015-03-02 09:19:46Z

1

Use a static Initialization block

static {
    //whatever code for initialization
}

A class can have any number of static initialization blocks
they can appear anywhere in the class body
static initialization blocks are called in the order that they appear in the source code.

You should be called every time when method called

public class Test {

    public static void checkServer() {
        if (!checkNetwork()) {
            return;
        }
    }

    public static void checkClient() {
        if (!checkNetwork()) {
            return;
        }
    }

    private static boolean checkNetwork() {
        return true; // or false depending on network condition
    }
}

edited Mar 2, 2015 at 9:19

answered Mar 2, 2015 at 8:56

Arun Kumar

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2 Comments

Arun Kumar Over a year ago

@TheLostMind I did not see the question has been edited?

Arun Kumar Over a year ago

@TheLostMind ok. Now what should i do?Can i update my answer?

Sam · Accepted Answer · 2015-03-02 08:44:16Z

0

You can use a static initialiser.

static {
    // code here
}

It will be run before any method of property (static or otherwise) of the class is first accessed.

answered Mar 2, 2015 at 8:44

Sam

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Comments

Balayesu Chilakalapudi · Accepted Answer · 2015-03-02 08:46:13Z

0

you can directly call a static method with the class name like this,

 boolean val=ABCServerUtil.checkServer();

some tutorial is given here

answered Mar 2, 2015 at 8:46

Balayesu Chilakalapudi

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Comments

Henry · Accepted Answer · 2015-03-02 08:59:49Z

0

Since there's already 5 answers saying the same thing and none of them seem to be what you're after:

A tool like Byte Buddy sounds like what you need.

answered Mar 2, 2015 at 8:59

Henry

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Comments

Community · Accepted Answer · 2017-05-23 12:12:53Z

-1

I think that this is your solution: Static initializer in Java

In practice you need a block of code executed the first time that your class is loaded.

edited May 23, 2017 at 12:12

CommunityBot

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answered Mar 2, 2015 at 8:48

Giovanni

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