java pass lambda as parameter

Lambda is a powerful thing introduced in Java 8 and since it’s launch it has becoming more and more common in use by the Java developers. Major reason behind switching to Java 8 is to get into the Lambda world. In this post, you will learn **How to Pass a Lambda as Parameter** to another method?

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**What is Lambda Expression?**

A lambda expression is an anonymous method which takes in parameters and returns a value. As it’s just an expression, It doesn’t execute by itself and therefore it’s basically used to implement methods of a Functional Interface.

Few Examples:

1 | i -> i + 10; |

1 | (i, j) -> i + j; |

1 | (i, j) -> {System.out.println(i-j);} |

**How to Pass Lambda expression as Method Parameter?**

In order to pass Lambda expression as a Method Parameter, the type of method parameter that receives must be of type of the Functional Interface.

**Example: Arithmetic Operations using Lambda Expression**

This is the easiest example on how to pass a Lambda as a parameter to another method.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | /** * Pass Lambda as Method Parameter * @author Deepak Verma * */ interface Arithmetic { int operation(int a, int b); } public class Pass_Lambda_As_Method_Parameter { public static void main(String[] args) { int a = 60; int b = 24; Arithmetic doAdd = (i,j) -> i + j; //Lambda Expression for Addition Arithmetic doSub = (i,j) -> i - j; //Lambda Expression for Subtraction Arithmetic doMul = (i,j) -> i * j; //Lambda Expression for Multiplication Arithmetic doDiv = (i,j) -> i / j; //Lambda Expression for Division //Pass Lambda Expression to another Method printAdd(doAdd,a,b); printAdd(doSub,a,b); printAdd(doMul,a,b); printAdd(doDiv,a,b); } public static void printAdd(Arithmetic x, int n1, int n2) { System.out.println("The Addition of "+n1+" and "+n2+": " + x.operation(n1, n2)); } public static void printSubtract(Arithmetic x, int n1, int n2) { System.out.println("The Subtraction of "+n1+" and "+n2+": " + x.operation(n1, n2)); } public static void printMultiply(Arithmetic x, int n1, int n2) { System.out.println("The Multiplication of "+n1+" and "+n2+": " + x.operation(n1, n2)); } public static void printDivide(Arithmetic x, int n1, int n2) { System.out.println("The Division of "+n1+" and "+n2+": " + x.operation(n1, n2)); } } |

**Let’s understand the code:**

**1.** Here we have a functional interface (Arithmetic) which has a method (Operation) that takes two integers and return an integer.

**2.** Now, let’s create Lambda Expression which takes two integers and return an integer after (adding / Subtracting / Multiplying / Dividing) those two integers.

1 | Arithmetic doAdd = (i,j) -> i + j; |

**3.** Finally, Create a static method (Print) that takes Lambda expression as an argument along with two integer values and Implement the method (Operation) of the Interface (Arithmetic) using that Lambda Expression.

1 2 3 | public static void printAdd(Arithmetic x, int n1, int n2) { System.out.println("The Addition of "+n1+" and "+n2+": " + x.operation(n1, n2)); } |

**4.** Then, just print the values using Sysout operation.

**Output**

1 2 3 4 | The Addition of 60 and 24: 84 The Addition of 60 and 24: 36 The Addition of 60 and 24: 1440 The Addition of 60 and 24: 2 |

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I hope you understand now, how to pass a Lambda expression as a parameter to another method.

This was the simplest example to make you clear enough on the working of the Lambdas in Java.

### java pass lambda as parameter

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