Java Community | Help. Code. Learn.•7mo ago

What is the benefit of using the Singleton pattern like this:

public static ConfigManager getInstance() {
        return ConfigManagerHolder.INSTANCE;
    }

    private static class ConfigManagerHolder {

        private static final ConfigManager INSTANCE = new ConfigManager();
    }
}

public static ConfigManager getInstance() {
        return ConfigManagerHolder.INSTANCE;
    }

    private static class ConfigManagerHolder {

        private static final ConfigManager INSTANCE = new ConfigManager();
    }
}

What is the benefit of having an internal class compared to just returning a new ConfigManager()

17 Replies

JavaBot•7mo ago

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userexitOP•7mo ago

so like in the first class have private static final ConfigManager INSTANCE; then inside getInstance() if null then create new else return current

nikcho-kouhai•7mo ago

I don't really think there is a benefit to this seems pretty pointless

Unknown User•7mo ago

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nikcho-kouhai•7mo ago

well it's fine if you aren't using multiple threads anyway

Unknown User•7mo ago

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nikcho-kouhai•7mo ago

(by lazy he means that the object isn't loaded when the object is needed, but is instead loaded anyway which is also true)

Unknown User•7mo ago

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userexitOP•7mo ago

how would you adapt this code to be an enum ?

nikcho-kouhai•7mo ago

    public enum Singleton{
        INSTANCE;
        private Singleton() {

        }
    }

    public enum Singleton{
        INSTANCE;
        private Singleton() {

        }
    }

userexitOP•7mo ago

what does the constructor do

nikcho-kouhai•7mo ago

well nothing in this case it just constructs the object you can remove the constructor in this case and a thing to note as borgel said generally speaking if you have to use a singleton you should probably restructure your code

Unknown User•7mo ago

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userexitOP•7mo ago

its just to load properties files that i will use across my program

Unknown User•7mo ago

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userexitOP•7mo ago

i do Properties instance no ? Properties properties = new Properties(); properties.load(fileInputStream) properties.getProperty(String key)...

JavaBot•7mo ago

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What is the benefit of using the Singleton pattern like this: