selenium.check("//input[@name=’checkboxes[]’ and @value=’cb3’]");

isChecked = driver.findElement(By.xpath("//input[@type='checkbox']"));

if (isChecked = false) {
    check the box;
} else {
    do nothing;
}

WebElement checkBox1;
WebElement checkBox3;

checkBox1 = driver.findElement(By.cssSelector("input[value='cb1']"));
checkBox3 = driver.findElement(By.cssSelector("input[value='cb3']"));

if(!checkBox1.isSelected()){
    checkBox1.click();
}

//checkBox3 is selected by default
if(checkBox3.isSelected()){
    checkBox3.click();
}

List<WebElement> selectElements=
driver.findElements(By.cssSelector("input[name='checkboxes[]']"));

selectElements.get(0).click();

if( selectElements.get(2).isSelected()){
    selectElements.get(2).click();
}

for(WebElement checkbox : selectElements){
    // uncheck 'em all
    if(checkbox.isSelected()){
      checkbox.click();
    }
}

IWebElement element = driver.findElement(By.xpath("//input[@type='checkbox']"));
if (!element.Selected)
{
    element.Click();
}

IWebElement chkBox = driver.FindElement(By.Id("some id "));
if (chkBox.Selected) {
  //perform actions
} else {
  //perform actions
}

/* load that webelement list of radio buttons. then follow the below code & logic */
List<WebElement> rdBtn_Sex = driver.findElements(By.name("sex"));

// Create a boolean variable which will hold the value (True/False)
boolean bValue = false;

// This statement will return True, in case of first Radio button is selected
bValue = rdBtn_Sex.get(0).isSelected();

// This will check that if the bValue is True means if the first radio button is selected
if (bValue = true) {
     // This will select Second radio button, if the first radio button is selected by default
    rdBtn_Sex.get(1).click();
} else {
     // If the first radio button is not selected by default, the first will be selected
     rdBtn_Sex.get(0)).click();
}