Jshell: Declare Methods

 

Step 1: Open terminal and execute jshell command

$jshell
|  Welcome to JShell -- Version 10.0.2
|  For an introduction type: /help intro

jshell>

 

Step 2: Execute following statements to define sum, sub methods.

 

int sum(int a, int b){

         return a + b;

}

 

int sub(int a, int b){

         return a - b;

}

jshell> int sum(int a, int b){
   ...>     return a + b;
   ...> }
|  created method sum(int,int)

jshell> 

jshell> int sub(int a, int b){
   ...>     return a - b;
   ...> }
|  created method sub(int,int)

jshell>

 

Step 3: You can use the command /methods to list the declared methods and their signatures.

jshell> /methods
|    int sum(int,int)
|    int sub(int,int)

Step 4: Execute below statements to call sum and sub methods.

int result = sum(10, 20)

int result = sub(10, 20)

jshell> int result = sum(10, 20)
result ==> 30

jshell> int result = sub(10, 20)
result ==> -10

How to update the method definition?

 

Step 1: Execute the command /list to see all the source that you have typed.

jshell> /list

   1 : int sum(int a, int b){
       	return a + b;
       }
   2 : int sub(int a, int b){
       	return a - b;
       }
   4 : int result = sub(10, 20);

Step 2: Numbers 1, 2 and 4 represent snippet ids. Execute the command ‘/edit 1’ to edit the definition of sum method.

Update the definition of sum method like below.

 

int sum(int a, int b){

         System.out.println("Calculating sum of " + a + " and " +  b);

         return a + b;

}

 

Click on Accept button.

 

Click on Exit button.

 

Re execute the command /list to see whether the definition of sum is updated or not.

jshell> /list

   2 : int sub(int a, int b){
       	return a - b;
       }
   4 : int result = sub(10, 20);
   5 : int sum(int a, int b){
       	System.out.println("Calculating sum of " + a + " and " +  b);
       	return a + b;
       }

jshell> sum(10, 20)
Calculating sum of 10 and 20
$6 ==> 30

 

 

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