When to use static in java

When to use:

You can add static when a method or variable needs to be initialized and loaded, or is often called. Methods modified with static can be called directly using the class name. If not, an object must be instantiated before calling.

Disadvantages:

Initial loading takes up more memory, so it is not recommended to add this keyword for methods that are not often used.

If you need to initialize your static variables through calculation, you can declare a static block. The Static block is only executed once when the class is loaded.

Recommended java related video tutorials: java online tutorial

The following example shows a class with a static method, some static variables, and a static initialization block.

Sample code:

// Demonstrate static variables，methods，and blocks.
class UseStatic {
static int a = 3;
static int b;
static void meth(int x) {
System.out.println("x = " + x);
System.out.println("a = " + a);
System.out.println("b = " + b);
}
static {
System.out.println("Static block initialized.");
b = a * 4;
}
public static void main(String args[]) {
meth（42）；
}
}

Once the UseStatic class is loaded, all static statements are run.

First, the class attribute variable starts to be assigned, a is set to 3, b is initialized to 0 by default, then the static block is run and executed (printing a message), and finally, b is initialized to a*4 or 12. Then main() is called, main() calls meth(), passing the value 42 to x, and the three println() statements refer to two static variables a and b, and the local variable x.

Note: It is illegal to reference any instance variables in a static method.

Run results:

Static block initialized.
x = 42
a = 3
b = 12

Recommended related article tutorials: Introduction to java programming

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