To troubleshoot please run below code 
import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.TimeUnit;
import javafx.scene.input.KeyCode;
import io.appium.java_client.AppiumDriver;
import io.appium.java_client.MobileBy;
import io.appium.java_client.MobileElement;
import io.appium.java_client.PressesKeyCode;
import io.appium.java_client.android.AndroidDriver;
import io.appium.java_client.android.AndroidKeyCode;
import io.appium.java_client.pagefactory.bys.builder.AppiumByBuilder;
import io.appium.java_client.remote.MobileCapabilityType;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.Assert;
public class Flipkart {
static AppiumDriver<MobileElement> driver = null;
public static void main(String[] args) {
try {
DesiredCapabilities caps = new DesiredCapabilities();
caps.setCapability(MobileCapabilityType.UDID, "ZY3222LHLW");
caps.setCapability(MobileCapabilityType.DEVICE_NAME, "MotoG5");
caps.setCapability(MobileCapabilityType.PLATFORM_NAME, "Android");
caps.setCapability(MobileCapabilityType.PLATFORM_VERSION, "7.1.1");
caps.setCapability(MobileCapabilityType.AUTOMATION_NAME,
"uiautomator2");
caps.setCapability("noReset", true);
caps.setCapability("systemPort",4798 );
caps.setCapability("newCommandTimeout", 300);
// caps.setCapability("eventTimings", "true");
caps.setCapability("appPackage", "com.flipkart.android");
caps.setCapability("appActivity",
".activity.HomeFragmentHolderActivity");
driver = new AndroidDriver<MobileElement>(new URL(
"http://127.0.0.1:4723/wd/hub"), caps);
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
Thread.sleep(5000);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
// driver.close();
driver.closeApp();
driver.quit();
}
}
}
The above code should launch flipkart application , if yes this confirms your setup is fine.
