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I try to count how often a static method is called and do not know how to do it, since I can not use an instance variable within the static method as far as I know. I have the following class:

public class Utilities {

     // print how often method was called + specific Value of Object o
     public static void showObject (Object o) {
          System.out.println(counter + ": " + o.toString());
     }
}

Printing the objects-values works, but how can I make the counter count? So the result for the following code should look like this:

    public static void main (String[] args){
    Object objectA = new Object ("Object A", 4);
    Object objectB = new Object ("Object B", 4);
    Object objectC = new Object ("Object C", 4);

    Utilities.showObject(objectB);
    Utilities.showObject(objectC);
    Utilities.showObject(objectC);
    Utilities.showObject(objectA);


1: 3.6
2: 8.0
3: 8.0
4: 9.2

Greetings and thanks, Patrick

You're going to want to create a static variable outside of the static method:

private static int counter = 0;

When the method is called, increment the variable:

public static void showObject(Object o){
    System.out.println(counter + ": " + o);
    counter++;
}

Java Static Keyword Explained With Examples, To invoke a instance method, we have to create an Object of the class in object they belong to because the this pointer is passed when you call them. Static methods are the methods in Java that can be called without creating an object of class. Program to calculate Electricity Bill � How to create a COVID-19 Tracker� As a result, you can use the class's name to call a static method or reference a static field. For example, if the count field is static in the Counter class, it means you can reference the variable with the following expression: Counter.count. Of course, access modifiers must be considered.

You can use a static variable to count the number of times the method is called.

public class Utilities {

     private static int count;

     public static void showObject (Object o) {
          System.out.println(counter + ": " + o.toString());
          count++;
     }

     // method to retrieve the count
     public int getCount() {
         return count;
     }
}

Static methods vs Instance methods in Java, In the above example, count is a variable that might be used to keep track of how many Likewise, a static method (no example shown) belongs to the class itself, not to When the program first starts, there are no instances (objects) yet to talk to, the calling method non-static, rather than to make the called method static. A static member function can be called even if no objects of the class exist and the static functions are accessed using only the class name and the scope resolution operator :: . We can’t put it in the class definition but it can be initialized outside the class as done in the following example by re-declaring the static variable, using the

Add static counter to your class:

public class Utilities {

     // counter where you can store info
     // how many times method was called
     private static int showObjectCounter = 0;

     public static void showObject (Object o) {
          // your code

          // increment counter (add "1" to current value")
          showObjectCounter++;
     }
}

Static, Object Orientation is a powerful technique when it comes to modelling real is in , move it to another pen, or count the total number of sheep that you own. class called Sheep which will make use of both static and non-static class variables and methods. http://www.pp.rhul.ac.uk/~george/PH2150/downloads/Sheep. java. public class MyClass { static int count = 0; public void myMethod() { count++; } } Using static int would seem a perfect solution. Static will share the instance variable count among all instances of MyClass. However, problem occurs in a multi threaded environment, as the count incrementation is not synchronised.

I can not use an instance variable within the static method as far as I know.

True, but fields can be static as well.

class Utilities {

    private static int counter;

    public static void showObject (Object o) {
        System.out.println(++counter + ": " + o.toString());
    }

}

Discussion of objects and static vs. non-static methods, For example, if the count field is static in the Counter class, it means you can Therefore, when using static variables, be sure that they are properly A static method can be called using the name of the class that declares it. In Java, a static member is a member of a class that isn’t associated with an instance of a class. Instead, the member belongs to the class itself. As a result, you can access the static member without first creating a class instance. The two types of static members are static fields and static methods: …

You can use the following:

private static final AtomicInteger callCount = new AtomicInteger(0);

and then in your method:

 public static void showObject (Object o) {
      System.out.println(callCount.incrementAndGet() + ": " + o.toString());
 }

Using AtomicInteger makes the counter thread-safe.

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Static keyword in Java, We have already seen that the Java Math class contains some useful static methods When we start to write non-static methods I will explain the distinction. to sum over, so we have to provide those two values when we call the method. For each value we want to examine we need to count how many times that value� A static method belongs to the class itself so a static method is also called class method. And since a static method doesn’t belong to any instances of the class, it cannot access non-static methods or non-static variables of the class. Because of this, beginners often make mistake of using non-static variables from a static method, causing

Methods, Static variable in Java: Only a single copy of static variable is created and Like variables we can have static block, static method and static class, to read about them it is much better to declare them static as this can save memory (because only class VariableDemo { static int count=0; public void increment() { count++; }� Write a static method eq() that takes two int arrays as arguments and returns true if the arrays have the same length and all corresponding pairs of elements are equal, and false otherwise. Solution. ArraysEquals.java. Write a static method sqrt() that takes a double argument and returns the square root

Java - static variable with example, Because a static variable is linked to a class and not to an object, it is perfect to is called, the object is created, and the static variable keeping the count of the With each object that we instantiate, we automatically call the constructor method. value by 1 each time the constructor is called (when a new object is created). count = count + 1; // Display count. System.out.println("Created object number: " + count); } } The static count variable is set to 0 at the instant it's created, right where it's declared. But every time a the constructor is invoked subsequently (by creating a new object in the 'main' method), it increments count.

Comments
  • what about a static variable? To easy?
  • you mean a static variable inside the main-method? I thought about this, but the problem is that i have 4 different files (4 different classes) which are all allowed to use the showObject-method. so i wanted to increment the counter inside the showObject-method to make sure it counts up whenever it is called. A static variable inside the showObject-Method would "die" when the method reaches the end, right?
  • What do you mean