Writing a lambda expression when parameters are ignored in the body

Dims :

How do I write a lambda expression if it doesn't require arguments and hence its name is excessive?

This way doesn't compile:

setRowFactory(-> new TableRowCustom());

But this one does:

setRowFactory(__ -> new TableRowCustom());

Is there a better way?

Sotirios Delimanolis :

Since you've mentioned that this works

setRowFactory(__ -> new TableRowCustom());

I assume that the expected functional interface method must accept a single argument. The identifier _ is a reserved keyword since Java 8.

I would just use a throwaway single (valid identifier) character.

setRowFactory(i -> new TableRowCustom());
setRowFactory($ -> new TableRowCustom()); // allowed, but avoid this

or even

setRowFactory(ignored -> new TableRowCustom());

to be explicit.

The Java Language Specification defines the syntax of a lambda expression

LambdaExpression:
  LambdaParameters -> LambdaBody 

and

LambdaParameters:
  Identifier
  ( [FormalParameterList] )
  ( InferredFormalParameterList )
InferredFormalParameterList:
  Identifier {, Identifier}

In other words, you cannot omit an identifier.

---

As Holger suggests, if and when they decide to use _ as an unused parameter name, it will be easy to change from __ to _ in your source code. You may want to just stick with that for now.

Guess you like

Origin http://10.200.1.11:23101/article/api/json?id=421011&siteId=1

Writing a lambda expression when parameters are ignored in the body

Pass parameters when the pyqt5 button is clicked (via lambda expression)

How to write a lambda expression when you are using a string array?

An error occurred when calling a local variable in a lambda expression

lambda expression

Resistor selection, these parameters cannot be ignored

driver.find_element_by_xpath () when writing parameters

Lambda expressions (lambda expression) ⭐⭐⭐⭐⭐

What is the `it` in Kotlin lambda body?

Decoding body parameters with Spring

Use lambda expression to act on button click event, PyQt5 pass parameters

Lambda (two) lambda expression uses

Indent lambda function body in Intellij

How to specify lambda expression in JAVA when I have two same name method?

jmeter regular expression writing

lambda expression parameter passing

lambda expression notes

C ++ 11 lambda expression

Lambda Expression definitions

C++ lambda expression

Java lambda expression understand

Learning Python expression --lambda

Kotlin_lambda expression

lambda expression format

lambda expression written

Lambda expression best practices

Inner class, lambda expression

java--lambda expression

The essence and application of lambda expression

Function (Lambda) expression learning