# Hide Default Constructor In Utility Classes
# Description
Utility classes are classes containing static properties only. Those classes should not be instantiated. A private constructor, which throws an IllegalStateException, is introduced to utility classes by this rule, if the following criteria are met:
- Only
staticmethods and fields are present - No constructor is declared
- No main method is defined
- The default constructor isn't invoked anywhere in the current workspace
This hides the default public constructor and thus prevents the instantiation of such a class.
# Benefits
Prevents the bad practice of unnecessary instatiation of utility classes.
# Tags
# Code Changes
Pre
public class UtilityClass {
public static void doSomething() {
//...
System.out.println("did something");
}
public static void doSomethingElse() {
//...
System.out.println("did something else");
}
}
Post
public class UtilityClass {
private UtilityClass() {
throw new IllegalStateException("Utility class");
}
public static void doSomething() {
//...
System.out.println("did something");
}
public static void doSomethingElse() {
//...
System.out.println("did something else");
}
}
You Want To Have Those Changes Done Automatically?
The automatic application of this rule is supported in the following jSparrow version: