How to take screenshot for only failed test cases using selenium web driver ?

import org.testng.annotations.Test;
import org.openqa.selenium.TakesScreenshot;
import java.io.File;
import org.apache.commons.io.FileUtils;
import org.openqa.selenium.By;
import org.openqa.selenium.OutputType;
import org.openqa.selenium.WebDriver;
import org.testng.annotations.BeforeTest;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterTest;

public class TakeScreenshot {

public WebDriver driver;              
@Test (description="take Screenshots if Test Case fails")
       public void TakeScreenshot() throws Exception {    
         driver.get("http://seleniumsubbu.blogspot.in/");
     try {              
             driver.findElement(By.id("xyz")).click();
           }
    catch(Exception e) {    
             System.out.println("Element Not Found");  
             takeScreenshot();    
          }    
       }
     public void takeScreenshot() throws Exception {            
          File f = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
          FileUtils.copyFile(f, new File("/home/chinna/selenium/seleniumSubbu.png")); //Linux path  
          // FileUtils.copyFile(f, new File("E:\\Workspace\\SeleniumSubbu.png"));          // for windows  path
       }
@BeforeTest
     public void beforeTest() {
      driver = new FirefoxDriver();
      driver.manage().window().maximize();
  }
@AfterTest
  public void afterTest() {
  }
}