Variables
Static variables are initialized
only once.

package com.minte9.oop.static_keyword;
public class Variables {
public static void main(String[] args) {
A a1 = new A();
A a2 = new A();
System.out.println(a1.getCount());
System.out.println(a2.getCount());
}
}
class A {
private static int count;
public A() {
count++;
}
public int getCount() {
return count;
}
}
Methods
Static methods
can't be access from a class instances.

package com.minte9.oop.static_keyword;
public class Methods {
public static void main(String[] args) {
System.out.println(
Math.round(42.2)
);
System.out.println(
Methods.myRound(33.5)
);
}
private static long myRound(Double n) {
return Math.round(n);
}
}
Classes
Only
nested classes can be static.

package com.minte9.oop.static_keyword;
public class Classes {
static int a = 10;
public static void main(String[] args) {
InnerClass.run();
}
static class InnerClass {
public static void run() {
System.out.println(a);
}
}
}