Java 11 and 12 – New Features

Overriding implicit behaviors

Suppose that you want to limit the values that can be passed to a field in your data class during its instantiation. This is feasible; just override the default constructor. The following is an example:

record Emp(String name, int age) { 
    // override default constructor 
    @Override 
    public Emp(String name, int age) { 
        // validate age 
        if (age > 70) 
            throw new IllegalArgumentException("Not employable above 70                         years"); 
        else { 
            // call default constructor 
            default.this(name, age); 
        } 
    } 
} 

Similarly, you can override the default implementations of object methods, such as equals(), hashCode(), and toString(), and other methods, such as the accessor methods.

Overriding the default behaviors of the methods of your data class ...