How do I fix a NoSuchMethodError?

Question

I\'m getting a NoSuchMethodError error when running my Java program. What\'s wrong and how do I fix it?

Answer 1

Try this way: remove all .class files under your project directories (and, of course, all subdirectories). Rebuild.

Sometimes mvn clean (if you are using maven) does not clean .class files manually created by javac. And those old files contain old signatures, leading to NoSuchMethodError.

Answer 2

I ran into a similar problem when I was changing method signatures in my application. Cleaning and rebuilding my project resolved the "NoSuchMethodError".

Answer 3

This is usually caused when using a build system like Apache Ant that only compiles java files when the java file is newer than the class file. If a method signature changes and classes were using the old version things may not be compiled correctly. The usual fix is to do a full rebuild (usually "ant clean" then "ant").

Sometimes this can also be caused when compiling against one version of a library but running against a different version.

Answer 4

This can also be the result of using reflection. If you have code that reflects on a class and extracts a method by name (eg: with Class.getDeclaredMethod("someMethodName", .....)) then any time that method name changes, such as during a refactor, you will need to remember to update the parameters to the reflection method to match the new method signature, or the getDeclaredMethod call will throw a NoSuchMethodException.

If this is the reason, then the stack trace should show the point that the reflection method is invoked, and you'll just need to update the parameters to match the actual method signature.

In my experience, this comes up occasionally when unit testing private methods/fields, and using a TestUtilities class to extract fields for test verification. (Generally with legacy code that wasn't designed with unit testing in mind.)

Answer 5

I had the same error:

  Exception in thread "main" java.lang.NoSuchMethodError: com.fasterxml.jackson.core.JsonGenerator.writeStartObject(Ljava/lang/Object;)V
        at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:151)
        at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292)
        at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3681)
        at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3057)

To solve it I checked, firstly, Module Dependency Diagram (click in your POM the combination -> Ctrl+Alt+Shift+U or right click in your POM -> Maven -> Show dependencies) to understand where exactly was the conflict between libraries (Intelij IDEA). In my particular case, I had different versions of Jackson dependencies.

1) So, I added directly in my POM of the project explicitly the highest version - 2.8.7 of these two.

In properties:

<jackson.version>2.8.7</jackson.version>

And as dependency:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>${jackson.version}</version>
</dependency>

2) But also it can be solved using Dependency Exclusions.

By the same principle as below in example:

  <dependency>
      <groupId>group-a</groupId>
      <artifactId>artifact-a</artifactId>
      <version>1.0</version>
          <exclusions>
             <exclusion>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-databind</artifactId>
             </exclusion>
         </exclusions>
  </dependency>

Dependency with unwanted version will be excluded from your project.

Answer 6

To answer the original question. According to java docs here:

"NoSuchMethodError" Thrown if an application tries to call a specified method of a class (either static or instance), and that class no longer has a definition of that method.

Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.

1. If it happens in the run time, check the class containing the method is in class path.
2. Check if you have added new version of JAR and the method is compatible.