error: package com.google.common.base does not exist

Question

given the following code in java, when compiling it u have a lot of errors :

---

Main.java:1: error: package com.google.common.base does not exist import com.google.common.base.Preconditions; ^

Main.java:2: error: package com.google.common.collect does not exist import com.google.common.collect.Lists; ^

Main.java:3: error: package org.ros.exception does not exist import org.ros.exception.RosRuntimeException; ^

Main.java:4: error: package org.ros.internal.loader does not exist import org.ros.internal.loader.CommandLineLoader; ^

Main.java:5: error: package org.ros.node does not exist import org.ros.node.DefaultNodeMainExecutor; ^

Main.java:6: error: package org.ros.node does not exist import org.ros.node.NodeConfiguration; ^

Main.java:7: error: package org.ros.node does not exist import org.ros.node.NodeMainExecutor;

I run it via IntelliJ. Does anyone know why it does not work?

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.ros.exception.RosRuntimeException;
import org.ros.internal.loader.CommandLineLoader;
import org.ros.node.DefaultNodeMainExecutor;
import org.ros.node.NodeConfiguration;
import org.ros.node.NodeMainExecutor;

// This class will run a publisher and subscriber, and relay data between them.

public class Main {

static private Talker pubNodeMain;

static private Listener subNodeMain;

public static void main(String[] argv) throws Exception {
    // Set up the executor for both of the nodes
    NodeMainExecutor nodeMainExecutor = DefaultNodeMainExecutor.newDefault();

    // Load the publisher
    String[] pubArgv = {"Talker"};
    CommandLineLoader pubLoader = new CommandLineLoader(Lists.newArrayList(pubArgv));
    String nodeClassName = pubLoader.getNodeClassName();
    System.out.println("Loading node class: " + pubLoader.getNodeClassName());
    NodeConfiguration pubNodeConfiguration = pubLoader.build();

    try {
        pubNodeMain = (Talker) pubLoader.loadClass(nodeClassName);
    } catch (ClassNotFoundException e) {
        throw new RosRuntimeException("Unable to locate node: " + nodeClassName, e);
    } catch (InstantiationException e) {
        throw new RosRuntimeException("Unable to instantiate node: " + nodeClassName, e);
    } catch (IllegalAccessException e) {
        throw new RosRuntimeException("Unable to instantiate node: " + nodeClassName, e);
    }

    Preconditions.checkState(pubNodeMain != null);
    nodeMainExecutor.execute(pubNodeMain, pubNodeConfiguration);

    // Load the subscriber
    String[] subArgv = {"Listener"};
    CommandLineLoader subLoader = new CommandLineLoader(Lists.newArrayList(subArgv));
    nodeClassName = subLoader.getNodeClassName();
    System.out.println("Loading node class: " + subLoader.getNodeClassName());
    NodeConfiguration subNodeConfiguration = subLoader.build();

    try {
        subNodeMain = (Listener) subLoader.loadClass(nodeClassName);
    } catch (ClassNotFoundException e) {
        throw new RosRuntimeException("Unable to locate node: " + nodeClassName, e);
    } catch (InstantiationException e) {
        throw new RosRuntimeException("Unable to instantiate node: " + nodeClassName, e);
    } catch (IllegalAccessException e) {
        throw new RosRuntimeException("Unable to instantiate node: " + nodeClassName, e);
    }

    Preconditions.checkState(subNodeMain != null);
    nodeMainExecutor.execute(subNodeMain, subNodeConfiguration);
  }

}

Answer 1

<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>11.0.2</version>
</dependency>

by adding dependency in pom.xml I was able to solve the problem

Answer 2

将此依赖项添加到您的 Gradle 文件中

compile "com.google.guava:guava:16+"

Answer 3

Anybody having similar issues, this is a dependency issue.

In IntelliJ:

1. Open the pom.xml file.
2. With the editor tab having the focus, choose Code | Generate on the main menu Code | Generate on the main menu , or press Alt+Insert , and choose Dependency from the Generate pop-up window.

That should fix this problem.

Answer 4

Are you using anything as a dependency manager? If you use something like maven, it will take care of getting the actual jars and putting them in your classpath.

There are many ways to add stuff to you classpath, but basically in one way or another something has to get the jars that contain the classes you want to import and reference them while compiling. Or else your local environment has no way to know what you're importing.

This is different from stuff you can import without any foreign jars. Packages such as java.util.*; come with the jdk you use which is why you can import them and compile without any further work.

Answer 5

Had this problem with a module which was once created as a native Intellij module instead of a Maven module.

I removed the module from the project and reimported as Maven module, so it resolved all libraries internally according to the pom.xml.