JAVA TUTORIALS

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Java8 Lambda Return Type

While the implementation of test() does move the computation of a test inside the java8 Interface where it belongs, it is the way to do it. With lambda Expression its easy to send data & get return value. Lambda reduces the code. You can see this in Example how lambda make it easy.

There are two important things to understand about returning values:
1. The type of data returned by a method must be compatible with the return type specified by the method. For example, if the return type of some method is boolean, you could not return an integer.
2. The variable receiving the value returned by a method must also be compatible with the return type specified for the method.

Creating Program in Java8(Lambda) for Return Type

Follow the below steps to write program with java8(Lambda).
Step-1

Create a package com.javat.java8 under sources package. Then create the Interface java8return.java. Once you are ready then write the code as shown below.

Step-2

Create the Java class java8returnvalue.java. Once you are ready then write the code as shown below.

Step-3

Create the Java class LamdaReturnType.java. Once you are ready then write the code as shown below.

package com.javat.java8;

interface java8return
{
    int test();
    
}

class java8returnvalue
{
    void run(java8return t)
    {
        System.out.println("inplemented method execute....");
       int val= t.test();
       System.out.println("return value is "+val);
    }
}
public class LamdaReturnType {
     public static void main(String args[])
    {
        
        java8returnvalue obj=new java8returnvalue();
        
        // before lamda expression we do like wise code
        // Anonymous Inner Class
        obj.run(new java8return(){
            @Override
            public int test()
            {
                System.out.println("without using java8 Lamda expression");
                System.out.println("before java 8 lamda expression need to write return type of method");
                return 1;
            }
            });
        
           // by using lamda expression we do like wise
           // it helps to pass the value or data to the function
          obj.run(() -> { 
            System.out.println("by using java8 lamda expression ");
            System.out.println("in java 8 no need to write return type of method");        
            return 2;
            });
          /*
           obj.run(() -> {                       
                 return 2;
                         });
          */
    }
}

Output

LamdaReturnType.java

Download example and run it on Netbeans IDE