Static

The Static Keyword

static members belong to a class rather than to an instance of a class. This allows them to be accessed Class.method() rather than classInstance.method().

Examples

Given the following class:

public class Operations {
  public final double pi = 3.14;

  /**
  * Tries to parse the given string to an integer.
  * Failure returns the default.
  * @param val String to parse
  * @param def Default value
  */
  public int tryParse(String val, int def) {
    try {
      return Integer.parseInt(val);
    } catch (NumberFormatException e) {
      return def;
    }
  }
}

You would need to create an instance of the Operations class to access the tryParse() method or pi.

Operations op = new Operations();
op.tryParse("123", -1);
System.out.println("Pi is " + op.pi);

That’s tedious and uses up unnecessary memory. Instead, we add the static keyword to the method.

public class Operations {
  public static final double pi = 3.14;

  /**
  * Tries to parse the given string to an integer.
  * Failure returns the default.
  * @param val String to parse
  * @param def Default value
  */
  public static int tryParse(String val, int def) {
    try {
      return Integer.parseInt(val);
    } catch (NumberFormatException e) {
      return def;
    }
  }
}

Now, we can skip the step of instantiating the Operations class:

Operations.tryParse("123", -1);
System.out.println(Operations.pi);