Java static keywordThe static keyword in Java is used for memory management mainly. We can apply static keyword with variables, methods, blocks and nested classes. The static can be:
1) Java static variableIf you declare any variable as static, it is known as a static variable.
Advantages of static variableIt makes your program memory efficient (i.e., it saves memory). Understanding the problem without static variableSuppose there are 500 students in my college, now all instance data members will get memory each time when the object is created. All students have its unique rollno and name, so instance data member is good in such case. Here, “college” refers to the common property of all objects. If we make it static, this field will get the memory only once. Java static property is shared to all objects.Example of static variableOutput: 111 Karan ITS 222 Aryan ITS Program of the counter without static variableIn this example, we have created an instance variable named count which is incremented in the constructor. Since instance variable gets the memory at the time of object creation, each object will have the copy of the instance variable. If it is incremented, it won’t reflect other objects. So each object will have the value 1 in the count variable. Output: 1 1 1 Program of counter by static variableAs we have mentioned above, static variable will get the memory only once, if any object changes the value of the static variable, it will retain its value. Output: 1 2 3 2) Java static methodIf you apply static keyword with any method, it is known as static method.
Example of static methodOutput:111 Karan BBDIT 222 Aryan BBDIT 333 Sonoo BBDIT Another example of a static method that performs a normal calculationOutput:125 Restrictions for the static methodThere are two main restrictions for the static method. They are:
Output:Compile Time Error Q) Why is the Java main method static?Ans) It is because the object is not required to call a static method. If it 3) Java static block
Example of static blockOutput:static block is invoked Hello main Q) Can we execute a program without main() method?Ans) No, one of the ways was the static block, but it was possible till JDK 1.6. Since JDK 1.7, it is not possible to execute a Java class without the main method. Output: static block is invoked Since JDK 1.7 and above, output would be: Error: Main method not found in class A3, please define the main method as: public static void main(String[] args) or a JavaFX application class must extend javafx.application.Application |
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