How to resize or maximize current browser window and get window size in Selenium Webdriver using java.

Get current window size

WebDriver driver = new FirefoxDriver(); 
driver.manage().window().getSize();  

Resize current browser window on width and height

WebDriver driver = new FirefoxDriver(); 
Dimension dimension=new Dimension(500, 600); 
driver.manage().window().setSize(dimension); 

Move browser window to specific point base on x and y coordinate

WebDriver driver = new FirefoxDriver(); 
Point point=new Point(100, 100) 
driver.manage().window().setPosition(point);  

Maximize current window size

WebDriver driver = new FirefoxDriver(); 
driver.manage().window().maximize(); 
OR

WebDriver driver = new FirefoxDriver(); 
Toolkit toolkit = Toolkit.getDefaultToolkit(); 
int Width = (int) toolkit.getScreenSize().getWidth(); 
int Height = (int) toolkit.getScreenSize().getHeight(); 
Dimension screenResolution = new Dimension(Width, Height); 
driver.manage().window().setSize(screenResolution); 

Example:

import java.awt.Toolkit; 
import java.util.concurrent.TimeUnit; 
import org.openqa.selenium.Dimension; 
import org.openqa.selenium.Point; 
import org.openqa.selenium.WebDriver; 
import org.openqa.selenium.firefox.FirefoxDriver; 
   
public class Resizewindow { 
 
public static void main(String args[]) throws InterruptedException { 
// Initialize firefox  driver       
WebDriver dr = new FirefoxDriver(); 
 
//Get current window size 
System.out.println(dr.manage().window().getSize()); 
 
// Resize browser window base on width and height 
dr.manage().window().setSize(new Dimension(500, 600)); 
System.out.println(dr.manage().window().getSize()); 
Thread.sleep(4000); 
 
//Move browser window to specific point base on x and y coordinate 
dr.manage().window().setPosition(new Point(20, 50)); 
System.out.println(dr.manage().window().getSize()); 
Thread.sleep(4000); 
 
//Maximize browser window        
dr.manage().window().maximize(); 
System.out.println(dr.manage().window().getSize()); 
Thread.sleep(4000); 
 
dr.manage().window().setPosition(new Point(0, 0)); 
dr.manage().window().setSize(new Dimension(500, 600)); 
Thread.sleep(4000); 
 
//Maximize browser window   
Toolkit toolkit = Toolkit.getDefaultToolkit(); 
int Width = (int) toolkit.getScreenSize().getWidth(); 
int Height = (int) toolkit.getScreenSize().getHeight(); 
Dimension screenResolution = new Dimension(Width, Height); 
dr.manage().window().setSize(screenResolution); 
System.out.println(dr.manage().window().getSize()); 
 
//close firefox browser   
dr.quit(); 
    } 

}