Solving NoSuchMethodError exception thrown using Reflection

问题

I am currently using Reflection to execute a set of methods in classes which reside in a different project than the one I am working on. These methods will in turn call other methods within this project. Although the method calling is succeeding, an InvocationTargetExceptioncaused by NoSuchMethodError is being thrown. I am presuming that this occurred because the methods I am calling using reflection call other methods. For this reason I have added to the class path the other project but this did not work.

Please note that the other project is an open source project I'm using from GitHub and am solely using it for analysis thus I do not want to manipulate with it.

Can anyone help me please?

Edit:

The following is my current code for reflection:

   public void runSelectedTests(MethodSignature test) throws Exception{
    //no paramater
    Class<?> noparams[] = {};

    try{
        //load the test at runtime
        //get the class
        Class<?> cls = Class.forName(test.getClassName());
        Constructor<?>[] cons = cls.getDeclaredConstructors();
        //can use the first constructor if there are multiple
        //if we instantiate with all constructors you end up calling the test methods depending on
        //how many constructors you have
        Constructor<?> cons1 = cons[0];
        Object params[] = null;
        if(cons1.getParameterTypes().length > 0){
            params = new Object[cons1.getParameterTypes().length];
        }
        for(int i = 0; i < cons1.getParameterTypes().length; i++){
            String type = cons1.getParameterTypes()[i].toString();
            if(type.equals("byte") || type.equals("short") || type.equals("int")){
                params[i] = 0;
            }else if(type.equals("long")){
                params[i] = (long)0.0;
            }else if(type.equals("float")){
                params[i] = (float)0.0; 
            }else if(type.equals("double")){
                params[i] = (double)0.0;
            }else if(type.equals("char")){
                params[i] = (char)0;
            }else if(type.equals("boolean")){
                params[i] = false;
            }else{
                params[i] = null;
            }   
        }

        Object obj = cons1.newInstance(params);
        //call the test method
        Method method = cls.getDeclaredMethod(test.getName(), noparams);
        method.invoke(obj, null);
    }catch(Exception e){
        System.out.println("exception "+e.getMessage());
    }
}

The object MethodSignature stores the method name and the fully qualified name of the class.

Stack Trace:

Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.Evaluation.TestRunner.runSelectedTests(TestRunner.java:72)
    at com.Main.AnalyserFactory.main(AnalyserFactory.java:41)
Caused by: java.lang.NoSuchMethodError: org.apache.commons.io.IOUtils.closeQuietly([Ljava/io/Closeable;)V
    at org.apache.commons.io.IOUtilsTestCase.testCloseQuietly_AllCloseableIOException(IOUtilsTestCase.java:134)
    ... 6 more

Edit

This is the method I am trying to call:

public void testCloseQuietly_AllCloseableIOException() {
    final Closeable closeable = new Closeable() {
        public void close() throws IOException {
            throw new IOException();
        }
    };
    IOUtils.closeQuietly(closeable, null, closeable);
}

The error seems to be on the line:

   IOUtils.closeQuietly(closeable, null, closeable);

回答1:

Class org.apache.commons.io.IOUtils does not have any method closeQuietly that takes java.io.Closeable as a parameter. It has following methods:

   closeQuietly(InputStream input) 
   closeQuietly(OutputStream output)
   closeQuietly(Reader reader)
   closeQuietly(Writer writer)

You shall pass your argument accordingly. Hope this helps.

回答2:

Since 1.5, all Method reflection methods are varargs for the parameter values/types.

This looks wrong:

method.invoke(obj, null);

If there are no parameters, call it thus:

method.invoke(obj);

Simlarly, this:

Method method = cls.getDeclaredMethod(test.getName(), noparams);

can/should be just

Method method = cls.getDeclaredMethod(test.getName());

来源：https://stackoverflow.com/questions/22116299/solving-nosuchmethoderror-exception-thrown-using-reflection

标签

java

reflection

nosuchmethoderror

invocationtargetexception