Step 1: Go to the source code functional interface for which you need to write lambda expressions and copy the parameters of its abstract method.
For example:
Let's say you want to write lambda expression for Consumer.
Step 3: Write the implementation similar to a method which takes String as input and returns nothing.
Please note that we need to use curly braces {} and a return statement when we want to execute multiple statements.
Now, let's say we are given a list of employee objects listOfEmployees and we need to obtain a list of the names of employees.
Here, we will use the map() method of the Stream API that takes a Function as a parameter.