Single Parameter

Description

For a single parameter lambda expression we can omit the parentheses as we omit the parameter type.

The lambda expression (String msg) -> {System.out.println(msg);} has everything.

Then we can omit the parameter type to have

We can further omit the parameter type and parentheses as follows.

Example

public class Main {
  public static void main(String[] argv) {
    Processor stringProcessor = str -> str.length();
    String name = "Java Lambda";
    int length = stringProcessor.getStringLength(name);
    System.out.println(length);/*from  w  w w. j  a  v a 2s .  c  om*/

  }
}

@FunctionalInterface
interface Processor {
  int getStringLength(String str);
}

The code above generates the following result.