实现时参考了本站另一个帖子 Toast 消息验证真的可以吗？[已测试验证，可以找到了]。
本帖是直接贴上我自己实现此功能的完整代码，如果想深入了解此功能，请移步到前文提到的帖子。

本人写的使用脚本实现捕获 Android Toast 内容的帖子：Appium+UiAutomator2 通过脚本验证 Toast 消息

使用 UiAutomator2：

1. capabilities.setCapability("automationName", "UiAutomator2");
2. 导入包 uiautomator-v18-2.1.1-release-no-dep.jar

OK，接下来就是上完整代码：

package com.example.test;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;

import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.remote.CapabilityType;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.support.ui.ExpectedCondition;
import org.openqa.selenium.support.ui.WebDriverWait;

import com.example.test.util.Constants;

import io.appium.java_client.android.AndroidDriver;

public class ToastValidateTest {

    private static final Logger LOGGER= Logger.getLogger(ToastValidateTest.class);

    private AndroidDriver<WebElement> driver;
    private WebDriverWait wait;

    @Before
    public void setUp() throws MalformedURLException {
        LOGGER.debug("setUp...");

        File classPathRoot = new File(System.getProperty("user.dir"));
        File appDir = new File(classPathRoot, "apps");
        File app = new File(appDir, Constants.test_app);
        DesiredCapabilities capabilities = new DesiredCapabilities();
        capabilities.setCapability("device", "Android");
        capabilities.setCapability(CapabilityType.BROWSER_NAME, "");
        capabilities.setCapability("unicodeKeyboard", true);
        capabilities.setCapability("resetKeyboard", true);
        capabilities.setCapability("platformName", "Android");
        capabilities.setCapability("deviceName", "Android");
        capabilities.setCapability(CapabilityType.VERSION, Constants.androidVersion);
        capabilities.setCapability(CapabilityType.PLATFORM, "MAC");
        capabilities.setCapability("app", app.getAbsolutePath());
        capabilities.setCapability("app-package", "com.example.test");
        capabilities.setCapability("app-activity", ".activity.SplashActivity");
        capabilities.setCapability("noReset", true);
        capabilities.setCapability("automationName", "UiAutomator2");
        driver = new AndroidDriver<WebElement>(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);

        wait = new WebDriverWait(driver, 10);

    }

    @After
    public void tearDown() {
        LOGGER.debug("tearDown...");
        if (null!= driver) {
            driver.quit();
        }
    }

    private boolean isElementFoundByText(String key, AndroidDriver<WebElement>driver) {
        try {

            @SuppressWarnings("unused")
            WebElement target= driver.findElementByXPath("//*[contains(@text, '"+ key+ " ')]");
            return true;
        } catch (Exception e) {
            return false;
        }

    }

    @Test
    public void testValidateToast() throws InterruptedException {

        Thread.sleep(3000);

        WebElement loginBtn= driver.findElementById("btn_login");
        Assert.assertNotNull(loginBtn);

        do {
            loginBtn.click();
        } while (isElementFoundByText("empty", driver));

        WebElement target= wait.until(new ExpectedCondition<WebElement>() {
            @Override
            public WebElement apply(WebDriver arg0) {
                return driver.findElementByXPath("//*[contains(@text, 'empty')]");
            }
        });

        String toastString= target.getAttribute("text");

        // 方便观察输出，多次重复输出获取到的Toast内容
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);
        LOGGER.debug("Toast: "+ toastString);

    }

}

测试在控制台的输出：

应用页面截图：

从上两图的对比中可以看到，控制台输出的 Toast 内容与应用页面上显示的 Toast 一致，说明测试确认捕获到了 Toast 的内容。