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package org.scijava.module;

import java.lang.reflect.Method;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import org.scijava.Validated;

import org.scijava.ValidityProblem;

/**

* A reference to a {@link Method}, which can be invoked at will.

*

* @author Curtis Rueden

*/

public class MethodRef implements Validated {

private final Method method;

private final String label;

/** List of problems when initializing the method reference. */

private final List<ValidityProblem> problems =

new ArrayList<>();

public MethodRef(final Class<?> clazz, final String methodName,

final Class<?>... params)

{

method = findMethod(clazz, methodName, params);

if (method == null) label = null;

else label = clazz.getName() + "#" + method.getName();

}

public void execute(final Object obj, final Object... args)

throws MethodCallException

{

executeWithResult(obj, args);

}

public Object executeWithResult(final Object obj, final Object... args)

throws MethodCallException

{

if (method == null) return null;

try {

return method.invoke(obj, args);

}

catch (final Exception exc) {

// NB: Several types of exceptions; simpler to handle them all the same.

throw new MethodCallException("Error executing method: " + label, exc);

}

}

private Method findMethod(final Class<?> clazz, final String methodName,

final Class<?>... params)

{

if (clazz == null) return null;

if (methodName == null || methodName.isEmpty()) return null;

for (Class<?> c = clazz; c != null; c = c.getSuperclass()) {

try {

final Method m = c.getDeclaredMethod(methodName, params);

m.setAccessible(true);

return m;

}

catch (final NoSuchMethodException e) {

// NB: Continue to loop into super class methods.

}

catch (final Exception e) {

// NB: Multiple types of exceptions; handle them all the same.

break;

}

}

final String problem =

"Method not found: " + clazz.getName() + "#" + methodName;

problems.add(new ValidityProblem(problem));

return null;

}

// -- Validated methods --

@Override

public boolean isValid() {

return problems.isEmpty();

}

@Override

public List<ValidityProblem> getProblems() {

return Collections.unmodifiableList(problems);

}

}