p -> p.getGender() == Person.Sex.MALE
  && p.getAge() >= 18
      && p.getAge() <= 25

p.getGender() == Person.Sex.MALE
      && p.getAge() >= 18
      && p.getAge() <= 25

  p -> {
    return p.getGender() == Person.Sex.MALE
        && p.getAge() >= 18
        && p.getAge() <= 25;
  }

  email -> System.out.println(email)

package com.zhyea.zytools;

public class Calculator {

  interface IntegerMath {
    int operation(int a, int b);
  }

  public int operateBinary(int a, int b, IntegerMath op) {
    return op.operation(a, b);
  }

  public static void main(String... args) {
    Calculator myApp = new Calculator();
    IntegerMath addition = (a, b) -> a + b;
    IntegerMath subtraction = (a, b) -> a - b;
    System.out.println("40 + 2 = " + myApp.operateBinary(40, 2, addition));
    System.out.println("20 - 10 = " + myApp.operateBinary(20, 10, subtraction));
  }
}

40 + 2 = 42
20 - 10 = 10

package com.zhyea.zytools;

import java.util.function.Consumer;

public class LambdaScopeTest {

  public int x = 0;

  class FirstLevel {

    public int x = 1;

    void methodInFirstLevel(int x) {
      //如下的语句会导致编译器在statement A处报错“local variables referenced from a lambda expression must be final or effectively final”
      // x = 99;
      Consumer<integer> myConsumer = (y) ->{
        System.out.println("x = " + x); // Statement A
        System.out.println("y = " + y);
        System.out.println("this.x = " + this.x);
        System.out.println("LambdaScopeTest.this.x = " + LambdaScopeTest.this.x);
      };

      myConsumer.accept(x);
    }
  }

  public static void main(String... args) {
    LambdaScopeTest st = new LambdaScopeTest();
    LambdaScopeTest.FirstLevel fl = st.new FirstLevel();
    fl.methodInFirstLevel(23);
  }
}

x = 23
y = 23
this.x = 1
LambdaScopeTest.this.x = 0

  Consumer<integer> myConsumer = (x) ->{
        // ....
      };

      //如下的语句会导致编译器在statement A处报错“local variables referenced from a lambda expression must be final or effectively final”
      x = 99;
      Consumer<integer> myConsumer = (y) ->{
        System.out.println("x = " + x); // Statement A
        System.out.println("y = " + y);
        System.out.println("this.x = " + this.x);
        System.out.println("LambdaScopeTest.this.x = " + LambdaScopeTest.this.x);
      };

   p -> p.getGender() == Person.Sex.MALE
          && p.getAge() >= 18
          && p.getAge() <= 25

public interface Runnable {
    void run();
  }

  public interface Callable<v> {
    V call();
  }

 void invoke(Runnable r) {
    r.run();
  }

  <t> T invoke(Callable<t> c) {
    return c.call();
  }