Help generated Java-file Protoc

I have this file suggested by ChatGPT.

I get all sorts for errors . Some I kind of understand, others not.

So if I generated a Java-file with protoc, should I run the Java-file from where I run Protoc?

import com.google.transit.realtime.GtfsRealtime.FeedMessage; import com.google.transit.realtime.GtfsRealtime.FeedEntity; import java.io.InputStream; import java.net.URL; public class GtfsReader {    public static void main(String[] args) throws Exception {        // Fetch the GTFS-Realtime feed        URL url = new URL("https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY");        InputStream in = url.openStream();        // Parse the feed into a FeedMessage object        FeedMessage feed = FeedMessage.parseFrom(in);        // Iterate through entities        for (FeedEntity entity : feed.getEntityList()) {            if (entity.hasAlert()) {                System.out.println("Alert: " + entity.getAlert().getHeaderText().getTranslation(0).getText());            }        }    } }

I get all sorts for errors .

Can you copy the full text of the error messages and paste them here?

protoc  is a compiler for .proto IDL files, which can be used to generate source for a variety of programming languages including Java, Kotlin, C++, Python, etc.

My choice for using a .proto file in a Java project would be to use Maven, and have it call protoc at build time.  

You would need to download the .proto file from https://gtfs.org/documentation/realtime/proto/ (or some other source), and then place it in the src/main/proto/ directory in your project.

When you build (mvn clean compile), the Java file(s) will be generated and placed under the project's target/generated-sources/protobuf/java directory.
target/generated-sources ├── annotations └── protobuf    └── java        └── com            └── google                └── transit                    └── realtime                        └── GtfsRealtime.java
Here's an example pom.xml<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <groupId>com.example</groupId>    <artifactId>demo</artifactId>    <version>1.0.0</version>    <packaging>jar</packaging>    <properties>        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>        <maven.compiler.release>11</maven.compiler.release>        <protobuf.version>3.25.3</protobuf.version>        <protobuf.maven.plugin.version>0.6.1</protobuf.maven.plugin.version>        <os.maven.plugin.version>1.7.0</os.maven.plugin.version>        <os-type>linux-x86_64</os-type>    </properties>    <dependencies>        <dependency>            <groupId>com.google.protobuf</groupId>            <artifactId>protobuf-java</artifactId>            <version>${protobuf.version}</version>        </dependency>    </dependencies>    <build>        <extensions>            <extension>                <groupId>kr.motd.maven</groupId>                <artifactId>os-maven-plugin</artifactId>                <version>${os.maven.plugin.version}</version>            </extension>        </extensions>        <plugins>            <plugin>                <artifactId>maven-compiler-plugin</artifactId>                <version>3.11.0</version>                <configuration>                    <release>${maven.compiler.release}</release>                </configuration>            </plugin>            <plugin>                <groupId>org.xolstice.maven.plugins</groupId>                <artifactId>protobuf-maven-plugin</artifactId>                <version>${protobuf.maven.plugin.version}</version>                <configuration>                    <protocArtifact>                        com.google.protobuf:protoc:${protobuf.version}:exe:${os-type}                    </protocArtifact>                </configuration>                <executions>                    <execution>                        <goals>                            <goal>compile</goal>                        </goals>                    </execution>                </executions>            </plugin>        </plugins>    </build> </project>


If you don't want to work with the .proto files, then you could add the dependency referenced here: https://mvnrepository.com/artifact/com.google.transit/gtfs-realtime-bindings to your project.

Here's an example pom.xml using the dependency:<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <groupId>com.example</groupId>    <artifactId>demo</artifactId>    <version>1.0.0</version>    <packaging>jar</packaging>    <properties>        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>        <maven.compiler.release>11</maven.compiler.release>        <os.maven.plugin.version>1.7.0</os.maven.plugin.version>    </properties>    <dependencies>        <!-- https://mvnrepository.com/artifact/com.google.transit/gtfs-realtime-bindings -->        <dependency>            <groupId>com.google.transit</groupId>            <artifactId>gtfs-realtime-bindings</artifactId>            <version>0.0.4</version>        </dependency>    </dependencies> </project>


And if you don't want to use Maven at all, then you could just download the  jar file from here: https://repo1.maven.org/maven2/com/google/transit/gtfs-realtime-bindings/0.0.4/gtfs-realtime-bindings-0.0.4.jar and use it directly in your project.

Norm Radder wrote:

I get all sorts for errors .

Can you copy the full text of the error messages and paste them here?

Not sure how to copy alot of errors but I took a screenschot.

Lars Persson wrote:Cannot resolve symbol 'google' :4
Cannot resolve symbol 'google' :5
Cannot resolve symbol 'FeedMessage' :18
Cannot resolve symbol 'FeedMessage' :22
Cannot resolve symbol 'FeedMessage' :26
Cannot resolve symbol 'FeedMessage' :35
Cannot resolve symbol 'FeedMessage' :41
Cannot resolve symbol 'FeedEntity' :42
Cannot resolve method 'getEntityList()' :42
Cannot resolve method 'hasTripUpdate()' :43
Cannot resolve symbol 'TripUpdate' :44
Cannot resolve method 'getTripUpdate()' :44
Cannot resolve method 'getTrip()' :45
Cannot resolve method 'getTrip()' :46
Cannot resolve method 'getStopTimeUpdateCount()' :47
Cannot resolve symbol 'FeedMessage' :53
Cannot resolve symbol 'FeedEntity' :54
Cannot resolve method 'getEntityList()' :54
Cannot resolve method 'hasAlert()' :55
Cannot resolve method 'getId()' :56
Cannot resolve method 'getAlert()' :57
'URL(java.lang.String)' is deprecated since version 20 :27
Typo: In word 'skane' :15
Typo: In word 'skane' :16

It looks like the classes/package are not visible to the compiler/IDE.  he required imports might be missing/errored or a library/dependency is not present.

Can you post the source code associated with the errors?

A fix for the URL warning would be to replace this:URL url = new URL("https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY");with this:URI uri = URI.create(    "https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY" ); URL url = uri.toURL();or just:URL url = URI.create(    "https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY" ).toURL();

Ron McLeod wrote:

Lars Persson wrote:Cannot resolve symbol 'google' :4
Cannot resolve symbol 'google' :5
Cannot resolve symbol 'FeedMessage' :18
Cannot resolve symbol 'FeedMessage' :22
Cannot resolve symbol 'FeedMessage' :26
Cannot resolve symbol 'FeedMessage' :35
Cannot resolve symbol 'FeedMessage' :41
Cannot resolve symbol 'FeedEntity' :42
Cannot resolve method 'getEntityList()' :42
Cannot resolve method 'hasTripUpdate()' :43
Cannot resolve symbol 'TripUpdate' :44
Cannot resolve method 'getTripUpdate()' :44
Cannot resolve method 'getTrip()' :45
Cannot resolve method 'getTrip()' :46
Cannot resolve method 'getStopTimeUpdateCount()' :47
Cannot resolve symbol 'FeedMessage' :53
Cannot resolve symbol 'FeedEntity' :54
Cannot resolve method 'getEntityList()' :54
Cannot resolve method 'hasAlert()' :55
Cannot resolve method 'getId()' :56
Cannot resolve method 'getAlert()' :57
'URL(java.lang.String)' is deprecated since version 20 :27
Typo: In word 'skane' :15
Typo: In word 'skane' :16

It looks like the classes/package are not visible to the compiler/IDE.  he required imports might be missing/errored or a library/dependency is not present.

Can you post the source code associated with the errors?

Thanks!

Ron McLeod wrote:A fix for the URL warning would be to replace this:URL url = new URL("https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY");with this:URI uri = URI.create(    "https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY" ); URL url = uri.toURL();or just:URL url = URI.create(    "https://opendata.samtrafiken.se/gtfs-rt-sweden/skane/ServiceAlertsSweden.pb?key=YOUR_KEY" ).toURL();

Thanks! I have tried alot of versions and will test again and probably come back.

Ok. I do feel stupid and lost.

How do I use the jar-file? Can I just copy the pom.xml if I start using Maven. (I have tried it a bit).

Here is what I did:

I fixed the protoc and the proto file.

Then ran this:

protoc --java_out = java2 gtfs-realtime.proto

This resulted in the path that Ron showed to GtfsRealtime.java.

As I understand (and I could be wrong) you shouldn't change this java-file. Instead you should use it's classes and functions in another file.

Here is where I go wrong. I tried to create a java-project using the help of chatGPT (or CoPilot which I think uses ChatGPT).

I pasted the code suggested by CoPilot but keep getting errors. That made me doubt that I had the project in the right place.

I am not an expert programmer but I do get that FeedMessage and FeedEntity (in the error-list) seems to be functions from GtfsRealtime.java.

Among other things this has confused me:

package com.google.transit.realtime;

I get an error but package is kind of namespace as I get it.

Also thinking I have the project in the wrong place since it's an path to GtfsRealtime.java.

I kind of feel like I came a long way and it shouldn't be to hard to solve. Still I'm stuck.

I have understood (I think) that you should'nt download the .pb-file but instead read the stream.

This is where I got the API from:

https://www.trafiklab.se/sv/api/gtfs-datasets/gtfs-sweden/realtime-specification/

Any more help would be greatly appreciated.

It would be helpful to understand what your development environment looks like.

From the image that you posted earlier, it looks like you are using the IntelliJ IDE - it that correct?

Ron McLeod wrote:It would be helpful to understand what your development environment looks like.

From the image that you posted earlier, it looks like you are using the IntelliJ IDE - it that correct?

Yes, I use IntelliJ.