Get toolTip on pie charts using selenium

package gooGle;

import java.util.concurrent.TimeUnit;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

public class Read_PieChart_ToolTip {

 WebDriver driver;

 @BeforeTest
 public void setup() throws Exception {
  driver = new FirefoxDriver();
  driver.manage().window().maximize();
  driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);
  driver.get("http://yuilibrary.com/yui/docs/charts/charts-pie.html");
 }

 @Test
 public void pieChart(){
  //Locate pie chart elements based on different colors.
  WebElement VioleteColor = driver.findElement(By.xpath("//*[contains(@class,'yui3-svgSvgPieSlice')][@fill='#66007f']"));
  WebElement GreenColor = driver.findElement(By.xpath("//*[contains(@class,'yui3-svgSvgPieSlice')][@fill='#295454']"));
  WebElement GreyColor = driver.findElement(By.xpath("//*[contains(@class,'yui3-svgSvgPieSlice')][@fill='#e8cdb7']"));
  WebElement LightVioleteColor = driver.findElement(By.xpath("//*[contains(@class,'yui3-svgSvgPieSlice')][@fill='#996ab2']"));
  WebElement BrownColor = driver.findElement(By.xpath("//*[contains(@class,'yui3-svgSvgPieSlice')][@fill='#a86f41']"));
 
  //locate tooltip pie chart.
  WebElement ToolTip = driver.findElement(By.xpath("//div[contains(@id,'_tooltip')]"));

  //Click on pie chart parts and get tooltip values.
  System.out.println("-X-X-X-X-X-X-X-X- Violete Part -X-X-X-X-X-X-X-X-");
  VioleteColor.click(); 
  System.out.println(ToolTip.getText());
  System.out.println(); 
 
  System.out.println("-X-X-X-X-X-X-X-X- Grey Part -X-X-X-X-X-X-X-X-");
  GreyColor.click();
  System.out.println(ToolTip.getText());
  System.out.println();
 
  System.out.println("-X-X-X-X-X-X-X-X- Light Violete Part -X-X-X-X-X-X-X-X-");
  LightVioleteColor.click();
  System.out.println(ToolTip.getText());
  System.out.println();
 
  System.out.println("-X-X-X-X-X-X-X-X- Green Part -X-X-X-X-X-X-X-X-");
  GreenColor.click();
  System.out.println(ToolTip.getText());
  System.out.println();
 
  System.out.println("-X-X-X-X-X-X-X-X- Brown Part -X-X-X-X-X-X-X-X-");
  BrownColor.click();
  System.out.println(ToolTip.getText()); 
 }
}