Java 14 new features that could be used to write code

Java14

Java 14 was released on March 17, 2020. Among the functions added in Java14, I would like to introduce the functions that can be used for writing code.

record(preview)

You can easily create a class for holding data.

public record Customer(String name, String age){}

The equivalent of the following class is created.

public class Customer {
    private final String name;

    private final String age;

    public Customer(String name, String age) {
        this.name = name;
        this.age = age;
    }

    public String name() {
        return this.name;
    }

    public String age() {
        return this.age;
    }

    public String hashCode() {...}

    public boolean equals() {...}

    public String toString() {...}
}

Since the method for setting the value is not defined, the value cannot be changed after the instance is created.

Text block

It is now possible to define a character string that includes line breaks. Enclosing a character string with "" instead of "" recognizes it as a text block.

String str1 = "aaaa\n"
    + "bbb";

String str2 = """
   aaa
   bbb\
   """

The above two strings indicate the same thing. If you do not want to start a new line, enter .

Helpful NullPointerExceptions

You can now get a detailed message when a NullPointerException occurs.

String str = null;
str.length(); // NullPointerException

By default, the following exception is output.

Exception in thread "main" java.lang.NullPointerException
	at Test.main(Test.java:5)

In java14, if you execute it with "-XX: + ShowCodeDetailsInExceptionMessages", the following detailed exception will be output.

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.length()" because "<local1>" is null
	at Test.main(Test.java:5)

Pattern matching instance of (preview)

You can now define variables of that type while checking the type with instanceof.

Object obj = "obj";
if (obj instanceof String str){
    System.out.println(str.length());
}