static method in kotlin

Note: The following is just my personal opinion. If there are any mistakes, please point them out.

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foreword

Static methods in kotlin are generally implemented through singleton classes, but singleton classes are not actually static in the true sense. If you want a real static method, you can use the @JvmStatic annotation or define a top-level method to achieve it.

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Implemented using a singleton class

When all are static methods

object ClassName{
    
    
    
}

This completes the creation of a singleton class, writes all the methods into the class, and the method is a static method.

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When only some methods are required to be static methods

class ClassName {
    
    
		fun doSomething1() {
    
    
			//dosmething
        }
    companion object{
    
    
        fun doSomething2() {
    
    
			//dosmething
        }
        fun doSomething3() {
    
    
			//dosmething
        }
    }
}

where doSomething1() is not a static method, doSomething2() and doSomething3()is a static method.

Implemented using annotations

class ClassName {
    
    
    companion object {
    
    
        @JvmStatic
        fun doSomething() {
    
    
            //dosomething
        }
    }
}

This will doSomething()define a real static method.

Implemented using top-level methods

Define the top-level file, and the methods defined in this file are all top-level methods, which are also real static methods.

  fun doSomething() {
    
    
			//dosmething
        }

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at last

Static methods are generally used as tool classes, except that annotations are not commonly used, and others are very common in kotlin.