Difference between throw and throws in java

throw keyword:

• throw keyword used to throw user defined exceptions.(we can throw predefined exception too)
• If we are having our own validations in our code we can use this throw keyword.
• For Ex: BookNotFoundException, InvalidAgeException (user defined).

Program:

1. package com.instanceofjava;
2. public class MyExceptionThrow {
3.  
4.  public static void main(String a[]){
5.  
6.  try{
7.  
8. MyExceptionThrow thr = new MyExceptionThrow();
9. System.out.println("length of INDU is "+thr.getStringSize("INDU"));
10. System.out.println("length of SAIDESH is "+thr.getStringSize("SAIDSH"));
11. System.out.println("length of null string is "+thr.getStringSize(null)); 
12.  
13.  }
14. catch (Exception ex){
15.   System.out.println("Exception message: "+ex.getMessage());  
16.  }
17.  }
18.  
19.  public int getStringSize(String str) throws Exception{
20.  
21.  if(str == null){
22.    throw new Exception("String input is null");  
23.  }
24.  return str.length();
25. }
26.  
27. }

Output
length of INDU is 4
length of SAIDESH is 5
Exception message: String input is null

throws keyword:

•  The functionality of throws keyword is only to explicitly to mention that the method is proven transfer un handled exceptions to the calling place.

Program:

1. package com.instanceofjava;
2. public class ExcpetionDemo {
3.  
4. public static void main(String agrs[]){
5.  
6. try
7. {
8. //statements
9. }
10. catch(Exception e)
11. {
12. System.out.println(e);
13. }
14. finally(){compulsorily executable statements
15. }
16. }
17.  
18. }

Closing All Tabs Using Robot Class In Selenium WebDriver

Closing All Tabs Using Robot Class In Selenium WebDriver

Earlier we have used java robot class to save Image from page In THIS POST. Robot class Is useful to send key-press and key-release events. We will use same thing here to perform keyboard ALT + SPACE + "c" (Shortcut key)  key-press events to close all tabs of browser. We can perform this key-press event sequence very easily using Robot class. I am suggesting you to use always WebDriver's driver.quit(); method to close all tabs of browser. Intention of this postIs to make you more aware about Robot class usage with selenium WebDriver so you can perform such tricky actions 

easily whenever required.

Bellow given example has used Robot class In @AfterTest methodto close browser tabs using ALT + SPACE + 'c' key-press event sequence. Run It In your eclipse IDE to check how It works.

package Testing_Pack;

import java.awt.AWTException;

import java.awt.Robot;

import java.awt.event.KeyEvent;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;

import org.openqa.selenium.Keys;

import org.openqa.selenium.WebDriver;

import org.openqa.selenium.firefox.FirefoxDriver;

import org.testng.annotations.AfterTest;

import org.testng.annotations.BeforeTest;

import org.testng.annotations.Test;

public class Tabs {

 WebDriver driver;

 Robot rb;

 @BeforeTest

 public void setup() throws Exception {

  driver = new FirefoxDriver();

  driver.manage().window().maximize();

  driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);

  driver.get("http://use any website try ur self");

 }

 @Test

 public void openTab() {  

  driver.findElement(By.cssSelector("body")).sendKeys(Keys.CONTROL +"t");

  driver.get("http:try your own");

  switchToTab();

  driver.findElement(By.xpath("//input[@id='6']")).click();

  driver.findElement(By.xpath("//input[@id='plus']"));

  driver.findElement(By.xpath("//input[@id='3']"));

  driver.findElement(By.xpath("//input[@id='equals']"));

  

  switchToTab();

  driver.findElement(By.xpath("//input[@name='FirstName']")).sendKeys("hi");

  driver.findElement(By.xpath("//input[@name='LastName']")).sendKeys("test");

  

  switchToTab();

  String str = driver.findElement(By.xpath("//input[@id='Resultbox']")).getAttribute("value");

  System.out.println("Sum result Is -> "+str);

 } 

 public void switchToTab() {  

  driver.findElement(By.cssSelector("body")).sendKeys(Keys.CONTROL +"\t");  

  driver.switchTo().defaultContent();  

 }

 @AfterTest

 public void closeTabs() throws AWTException {

  //Used Robot class to perform ALT + SPACE + 'c' keypress event.

  rb =new Robot();

  rb.keyPress(KeyEvent.VK_ALT);

  rb.keyPress(KeyEvent.VK_SPACE);

  rb.keyPress(KeyEvent.VK_C);

 }

}

Difference between Collections and Collection in java with example program

Difference between Collections and Collection in java with example program

Famous java interview question: difference between collections and collection in java
Major difference between Collection and Collections is Collection is an interface and Collections is a class.
Both are belongs to java.util package
Collection is base interface for list set and queue.
Collections is a class and it is called utility class.
Collections utility class contains some predefined methods so that we can use while working with
Collection type of classes(treeset, arraylist, linkedlist etc.)
Collection is base interface for List , Set and Queue.


Collection vs Collections

public interface Collection<E>
extends Iterable<E>


public class Collections
extends Object

Collections utility class contains static utility methods so that we can use those methods by using
class name without creating object of Collections class object
Lest see some methods of Collections class.


addAll: public static <T> boolean addAll(Collection<? super T> c,T... elements)
reverseOrder: public static <T> Comparator<T> reverseOrder()
shuffle: public static void shuffle(List<?> list)
sort:public static <T extends Comparable<? super T>> void sort(List<T> list)
How to Relate Collection and Collections
ArrayList is a Collection type of class means it is implementing Collection interface internally
Now lets see a java example program to sort ArrayList of elements using Collections.sort() method.

public class ArrayList<E>
extends AbstractList<E>
implements List<E>, RandomAccess, Cloneable, Serializable


1.Basic Java example program to sort arraylist of integers using Collections.sort() method

package com.javasortarraylistofobjects;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;

public class SortArrayListExample{

public static void main(String[] args) {

//create an ArrayList object
 ArrayList<Integer> arrayList = new ArrayList<Integer>();
     
 //Add elements to Arraylist
arrayList.add(10);
arrayList.add(7);
arrayList.add(11);
arrayList.add(4);
arrayList.add(9);
arrayList.add(6);
arrayList.add(2);
arrayList.add(8);
arrayList.add(5);
arrayList.add(1);
     
     
 System.out.println("Before sorting ArrayList ...");
 Iterator itr=arrayList.iterator();
     
while (itr.hasNext()) {

System.out.println(itr.next());
   
}

     
 /*
 To sort an ArrayList object, use Collection.sort method. This is a
  static method. It sorts an ArrayList object's elements into ascending order.
*/
  Collections.sort(arrayList);
   
  System.out.println("After sorting ArrayList ...");
     
 
     
Iterator itr1=arrayList.iterator();
     
while (itr1.hasNext()) {

System.out.println(itr1.next());
         
}
 

}
}



Output:

Before sorting ArrayList ...
10
7
11
4
9
6
2
8
5
1
After sorting ArrayList ...
1
2
4
5
6
7
8
9
10
11