how to execute copy/paste using selenium webdriver

I want to execute a paste to a local variable already exist to an input text with selenium webdriver in java. for this I used this method:

public static void copyText(final String id, final String text) throws Exception {
        waitForJQueryProcessing(DRIVER, N_30);
        WebElement elem = DRIVER.findElement(By.id(id));
        DRIVER.findElement(By.id(id)).clear();
        Toolkit toolkit = Toolkit.getDefaultToolkit();
        Clipboard clipboard = toolkit.getSystemClipboard();
        StringSelection strSel = new StringSelection(text);
        clipboard.setContents(strSel, null);
        elem.sendKeys(Keys.chord(Keys.CONTROL, "v", text));
        System.out.println(text);

    }

When I execute the test, i will appear empty I don't know why ?