java空点异常无法解决

Question

这是我的代码

package ecommerce;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class Classwithmultiplemethods {

    public static WebDriver driver;

    public static void browser(){
        WebDriver driver;
        System.setProperty("webdriver.chrome.driver", "D:\\Selenium\\selenium-java-3.141.59\\libs\\chromedriver.exe");
        driver = new ChromeDriver();
        driver.get("https://www.google.com/");
        driver.manage().window().maximize();
        driver.get("http://newtours.demoaut.com/");
    }

    public static void clicklinks() {

            System.out.println("new tours");
            driver.findElement(By.linkText("REGISTER")).click();
            /*driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
            driver.findElement(By.linkText("తెలుగు")).click();
            driver.findElement(By.linkText("English")).click();
            driver.findElement(By.linkText("हिन्दी")).click();
            driver.findElement(By.linkText("English")).click();*/
}

    public static void teardown() {
        driver.quit();
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        browser();
        clicklinks();
        teardown();
    }

}

引发此错误，请帮助我解决

  

线程“主”中的异常java.lang.NullPointerException       在ecommerce.Classwithmultiplemethods.clicklinks（Classwithmultiplemethods.java:25）       在ecommerce.Classwithmultiplemethods.main（Classwithmultiplemethods.java:41）