Exception in thread "main" java.lang.NoSuchMethodError [duplicate]

This question already has answers here: Closed 10 years ago. 开发者_运维百科

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Causes of 'java.lang.NoSuchMethodError: main Exception in thread “main”'

i got this error after i added a method called setConstraints in Generator.class.im free from error when i compiled. this is the error: Exception in thread "main" java.lang.NoSuchMethodError: rtg.Generator.setConstra ints(Ljava/util/ArrayList;)V at rtg.DefaultPrompt.main(DefaultPrompt.java:117)

this is the method of setCostraints() in Generator.java

private ArrayList<String> constraints_list = new ArrayList<String>();
private boolean constr = false;
public void setConstraints(ArrayList<String> c)
    {
        constraints_list = c;
        constr = true;
    }

this the class that is using Generator.class

public class DefaultPrompt
{
  public static void main()
  {   
      Generator gen = new Generator();
      gen.setConstraints(constraints_list);
  }
{

both classes r in the same package.before added setConstraints, no error.

anyone knows how/why its happen?

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Sounds like the class was not re-compiled after you added the method. Sometimes this happens in some environments. Try deleting all the .class files in the directory and re-compiling again.

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did u noticed the error clearly u can see the space in the method name

Exception in thread "main" java.lang.NoSuchMethodError: rtg.Generator.setConstra ints(Ljava/util/ArrayList;)V at rtg.DefaultPrompt.main(DefaultPrompt.java:117)