Some useful vscode shortcuts you must know which save your time.
1. To open vs code from the command prompt
cmd> code .
2. To open a terminal in vs code
ctrl + `
java is a case sensitive language, that means there is a seperate recognization for uppercase letters and lower case letters.
Exampleabcis not equal to ABC(ABC != abc).
java has the following naming conventions, they are
all classes, abstract classes, and interfaces Names must be started with uppercase letters and their subsequent symbols must be uppercase letters.
Example:
String
StringBuffer
all variables must be started with lowercase letters and subsequent symbols must be uppercase letters.
Example:
nameIsZaheer
all methods must be started with lowercase letters and subsequent symbols must be uppercase letters.
Example:
additionWithTwoParameters()
additionWithThreeParameters()
all constant variables must be in uppercase letters only.
Example:
GLOBAL_VARIABLE
All the package names must be in lowercase letters.
Example:
com.zaheerintrovert.javanamingconventions
Scanner class is used to read data from keyboard, and it is from util package.
below program "addition of two numbers"
package basics;
import java.util.Scanner;
public class readFromKeyboard {
public static void main(String[] args) {
Scanner read = new Scanner(System.in);
int FirstNumber;
int SecondNumber;
int Result;
System.out.println("enter first number");
FirstNumber = read.nextInt();
System.out.println("enter second number");
SecondNumber = read.nextInt();
Result = FirstNumber + SecondNumber;
System.out.println("the result is " + Result);
}
}
note:
To know the methods present in that scanner class we have the command javap java.util.Scanner
To check it open the command prompt and enter the command, then you will get the list of methods present in the scanner Class.
Some of the methods are listed below
nextInt()
nextFloat()
nextDouble()
next()
nextLine()
nextBoolean()
nextByte()
nextShort()
nextLong()
etc...for learn java programming we required JDK
JDKthat is java development kit used for compiling java programs or debugging etc... it consists of compiler and other tools along with JRE
Once we compiled the program we need to execute it for that we need JREjava runtime environment which is the part of jdk.
JRE it contains class libraries along with JVM.
JVM it is java virtual machine, its a part of JRE.
you can imagine like JDK is for developing and JRE for executing and for executing we required JVM which is the part of the JRE.
JVM will execute the programs
Example:
HelloWorld.java it is a our program file.
Now, we will compile the file using the command javac HelloWorld.java
note: javac is a part of JDK, aftering compiling the program file we get the .class i.e HelloWorld.class
Now, for running this .class file i.e HelloWorld.class we have the command java HelloWorld, helloworld is the file name.
java command is nothing but jvm which is the part of JRE therefore JDK will compile and JRE will execute the program.
its better to download the latest version. you can download the required version from the above link.
install the java into your machine.
and now check the version of the java by running the following command in the command prompt java -version
If you get the version then congratulations you have successfully downloaded the java into your machine and have already set the path.
If you doesn't get the java version and instead of version if you the message like java is not recognized as internal or external command,operable program or batch file then you need to set the path.
To set the path follow the below procedure...
we can set the path as local as well as global. the advantage of setting the path as global is we can able to use it from any location from the machine.
To set the path as local, open the command prompt set the path by running the command set path=C:\Program Files\Java\jdk-11.0.14\bin;%path%;
In my case the java is located at this location. C:\Program Files\Java\jdk-11.0.14\bin and %path% is for not to delete the other paths which have already set by default or by manually.
copy the java path in my case C:\Program Files\Java\jdk-11.0.14\bin now open control panel and click on system and security
now click on the advanced system settings then you will find the Environment variables button below.
click on Environment variables and here you will find the two halfs. i.e., user settings and system settings.
In both settings you will find the Path named value click on that and then press edit option below, and now paste the java bin link and apply and close it.
Note: If you pasted the java link in user settings it is for particular user only. and if you pasted the java path in system settings then java can be used globally and any user of your system can use the java.
Tips:
you can use the command cls in command prompt to clear the screen.
Postman, It is a platform for building and using API.
We can manage a complete API lifecycle with postman.
A postman help us to do.
Developmenta website which consist of sample dummpy API'S for the practice purpose visit Click Here
We can get a endpoint to use in postman
The common http methods are
GET To get the values
POST To create the values
PUT To update the values
DELETE To delete the Resources
PATCHTo update the particular field.
Note:Put will replace the resources, and patch will be used for particular field updates and we can give only required fields in the body instead of whole body fields.
You can visit the link for more information about HTTP methods Click Here
It is a Group of API requests
Variables are key value pairs or elements that can store different values.
we can reuse the value at Multiple locations if required.Change can be done at a single place.
Advantagewe can store URLS or etc in varaibles and we can use this variable in double curly braces {{name of the variable}}. instead of using the lengthy values. And this method can be used when some values is repeatedly used at multiple places. We can extract out all common values and keep them at one place.
Below the request section we can see the tests section in that we can add scripts to set and get varaibales.
Pre-req Scripts executes before running the requests
testScripts executes after running the request.
Global level: pm.globals.set("name","zaheer");
collection level: pm.collectionVariables.set("name","zaheer");
Environment Level: pm.environment.set"name","zaheer");
local level: pm.variables.set("name","zaheer");
global level: pm.globals.get("name");
or
console.log(pm.globals.get(name);
or
we can store it in variable and then we can call exaample:
let value = pm.globals.get(name);
console.log(value);
collection level: pm.collectionVariables.get("name");
environment level: pm.environment.get("name");
local level: pm.variables.get("name");
note:
Access a variable at any scope, including local, based on priority.
local --> data --> environment --> collection --> global
to remove: pm.enviroment.unset("name");
Environment is a set of key value pairs.
we can use it to store variables which can be used in requests and body and scripts etc...
example:
we can store a request url in a enviroment variable and instead of URL we can use that variable
endpoint=localhost:9008/rest/api/
at the reqest body: http://{{endpoint}}/user.
When we open any request, We can see pre-request script.= we can create any sctipts and this scripts
will get executed before we run And we have the test section here also we can create the scripts and the
scripts get executed after the getting a response from the server.
Tests in Postman are JavaScript code that is executed after receiving response. We can add test scripts as at a request level, collection level and folder level.
Debugging in the console. Every request sent by Postman is logged in the console, so you can view the detail of what happened when you sent a request. This means you can use the Postman Console to help debug your requests when an API isn't behaving as you expect.
example:
we can run and check the pre-request script
console.log("this is a log");
console.info("this is a info");
console.warn("this is warn");
console.error("this is a error");
Now, open console we can check it.
To get the data from CSV or Json file first we have to create a file and add a data in the file and save the file with CSV or Json Extension
Now to add this file first click on Collection then click on three dots on right top on that collection,then you will get the run collection option, select a request method Then you will get.an option like Select file option then you have to upload respected csv or json file And run.
APIs use authorization to ensure that client requests access data securely. This can involve authenticating the sender of a request and confirming that they have permission to access or manipulate the relevant data. If you're building an API, you can choose from a variety of auth models. If you're integrating a third-party API, the required authorization will be specified by the API provider.
DocumentationClick Here
Additional information: Click Here
