Question

我正在编写一个Java代码，可以在Chrome或Firefox中运行简单的自动化方案 - 具体取决于用户的输入。它开始运行（打开浏览器），但随后抛出java.lang.NullPointerException。我当时认为我分配了驱动程序变量的null稍后会被覆盖，但事实并非如此。怎么解决这个问题？谢谢！

package com.selenium;

import java.util.Scanner;

import org.openqa.selenium.By;
import org.openqa.selenium.Keys;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class Main {

    public static void main(String[] args) throws InterruptedException {
        // environment variable
        System.setProperty("webdriver.chrome.driver", "C:\\Automation\\libs\\Drivers\\chromedriver.exe");
        //WebDriver chromeDriver = new ChromeDriver();
        System.setProperty("webdriver.gecko.driver", "C:\\Automation\\libs\\Drivers\\geckodriver.exe");
        WebDriver driver = null;

        Scanner scanner = new Scanner(System.in);
        int option = scanner.nextInt();
        System.out.println("Please enter 1 for Chrome or 2 for Firefox " + option);
        if (option == 1)
        {
            WebDriver driver1= new FirefoxDriver();
        }
        else if 
        (option == 2)
        {
            WebDriver driver2 = new ChromeDriver();
        }
        else 
            System.out.println("Please enter a correct number " + option);

        String baseURL = "https://login.salesforce.com/?locale=eu";

        driver.get(baseURL);

        WebElement userName = driver.findElement(By.id("username"));
        userName.sendKeys("Yan");

        WebElement password = driver.findElement(By.id("password"));
        password.sendKeys("123456");

        WebElement rememberCheckbox = driver.findElement(By.id("rememberUn"));
        rememberCheckbox.click();

        WebElement bLogin = driver.findElement(By.id("Login"));
        bLogin.click();

        }

    }

Answer 1

永远不会分配

驱动程序，只需创建新驱动程序即可。变化：

    if (option == 1)
    {
        WebDriver driver1= new FirefoxDriver();
    }
    else if 
    (option == 2)
    {
        WebDriver driver2 = new ChromeDriver();
    }

为：

    if (option == 1)
    {
        driver = new FirefoxDriver();
    }
    else if 
    (option == 2)
    {
        driver = new ChromeDriver();
    }

Answer 2

我猜driver.get(baseURL);会抛出。在条件语句的主体中，您正在创建新变量（driver1，driver2），并且从不使用它们。请为先前声明的driver变量赋值。

if (option == 1)
{
   WebDriver driver1= new FirefoxDriver();
}

会变成

if (option == 1)
{
   driver = new FirefoxDriver();
}

和

else if (option == 2)
{
   WebDriver driver2 = new ChromeDriver();
}

会变成

else if (option == 2)
{
   driver = new ChromeDriver();
}

Answer 3

查看第driver.get(baseURL)行

您在此Object上调用方法，但此时此对象仍为null。

这就是发生NullPointerException的原因。

Answer 4

以下是您的问题的答案：

您必须按照以下方式处理代码中的大量事实：

将const redis = require('redis'); const redisClient = redis.createClient(); var values ; redisClient.flushall(); redisClient.hmset('Angelica', { "Blues Traveler": 3.5, "Broken Bells": 2.0, "Norah Jones": 4.5, "Phoenix": 5.0, "Slightly Stoopid": 1.5, "The Strokes": 2.5, "Vampire Weekend": 2.0 }); redisClient.hmset('Bill', { "Blues Traveler": 2.0, "Broken Bells": 3.5, "Deadmau5": 4.0, "Phoenix": 2.0, "Slightly Stoopid": 3.5, "Vampire Weekend": 3.0 }); redisClient.hmset('Dan', { "Blues Traveler": 3.0, "Broken Bells": 4.0, "Deadmau5": 4.5, "Phoenix": 3.0, "Slightly Stoopid": 4.5, "The Strokes": 4.0, "Vampire Weekend": 2.0 }); redisClient.hmset('Hailey', { "Broken Bells": 4.0, "Deadmau5": 1.0, "Norah Jones": 4.0, "The Strokes": 4.0, "Vampire Weekend": 1.0 }); redisClient.hmset('Jordyn', { "Broken Bells": 4.5, "Deadmau5": 4.0, "Norah Jones": 5.0, "Phoenix": 5.0, "Slightly Stoopid": 4.5, "The Strokes": 4.0, "Vampire Weekend": 4.0 }); redisClient.hmset('Sam', { "Blues Traveler": 5.0, "Broken Bells": 2.0, "Norah Jones": 3.0, "Phoenix": 5.0, "Slightly Stoopid": 4.0, "The Strokes": 5.0 }); redisClient.hmset('Veronica', { "Blues Traveler": 3.0, "Norah Jones": 5.0, "Phoenix": 4.0, "Slightly Stoopid": 2.5, "The Strokes": 3.0 }); redisClient.hmset('Chan', { "Blues Traveler": 5.0, "Broken Bells": 1.0, "Deadmau5": 1.0, "Norah Jones": 3.0, "Phoenix": 5, "Slightly Stoopid": 1.0 }); redisClient.keys('*', (err, responde) => { redisClient.hmget(responde); values=responde.toLocaleString() console.log(responde.toLocaleString()) }) console.log( values)的配置与environment variable中的System.setProperty循环保持一致。
打印文本for()后保留第scanner.nextInt()行。
完成扫描仪实例的使用后，请将其关闭以防止将来Please enter 1 for Chrome or 2 for Firefox。
在Resource Leakage范围内将WebDriver个实例的名称保留为driver。
在您的代码中，您在开始时已将Automation Framework个实例声明为WebDriver，而您正在尝试再次启动null或driver1。因此，您遇到了 driver2
以下是根据您的要求使用Mozilla Firefox的示例代码块，浏览到网址java.lang.NullPointerException，提供用户名＆amp;密码，最后点击https://login.salesforce.com/按钮：
```
Log In
```

执行此程序时，您将在控制台上观察到以下输出：

package demo;

import java.util.Scanner;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class Q45482474 {

    public static void main(String[] args) {


    WebDriver driver = null;

    Scanner scanner = new Scanner(System.in);
    System.out.println("Please enter 1 for Chrome or 2 for Firefox : ");
    int option = scanner.nextInt();
    scanner.close();
    if (option == 1)
    {
        System.setProperty("webdriver.gecko.driver", "C:\\Utility\\BrowserDrivers\\geckodriver.exe");
        driver= new FirefoxDriver();
    }
    else if 
    (option == 2)
    {
        System.setProperty("webdriver.chrome.driver", "C:\\Utility\\BrowserDrivers\\chromedriver.exe");
        driver = new ChromeDriver();
    }
    else 
        System.out.println("Please enter a correct number.");

    String baseURL = "https://login.salesforce.com/?locale=eu";

    driver.get(baseURL);

    WebElement userName = driver.findElement(By.id("username"));
    userName.sendKeys("Yan");

    WebElement password = driver.findElement(By.id("password"));
    password.sendKeys("123456");

    WebElement rememberCheckbox = driver.findElement(By.id("rememberUn"));
    rememberCheckbox.click();

    WebElement bLogin = driver.findElement(By.id("Login"));
    bLogin.click();

    }

}

如果这回答你的问题，请告诉我。

我的Java代码抛出java.lang.NullPointerException

4 个答案: