org.carrot2.util.ExceptionUtils Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of carrot2-core Show documentation
Carrot2 Text Clustering Library
There is a newer version: 4.6.0
/*
 * Carrot2 project.
 *
 * Copyright (C) 2002-2021, Dawid Weiss, Stanisław Osiński.
 * All rights reserved.
 *
 * Refer to the full license file "carrot2.LICENSE"
 * in the root folder of the repository checkout or at:
 * https://www.carrot2.org/carrot2.LICENSE
 */
package org.carrot2.util;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Constructor;

/** A number of utility classes for working with {@link Throwable}s. */
public final class ExceptionUtils {
  private ExceptionUtils() {
    // No instantiation
  }

  /**
   * If t if an instance of clazz, then t is returned.
   * Otherwise an instance of clazz is created using a single-parameter constructor
   * accepting t and the wrapper exception instance is returned. If no matching
   * constructor can be found, a {@link RuntimeException} is returned.
   *
   * @param clazz The exception class to return (or wrap) t.
   * @param t Throwable instance to wrap.
   */
  public static  T wrapAs(Class clazz, Throwable t) {
    if (t == null) {
      return null;
    }

    if (clazz.isAssignableFrom(t.getClass())) {
      return clazz.cast(t);
    }

    try {
      @SuppressWarnings("unchecked")
      final Constructor[] constructors = (Constructor[]) clazz.getConstructors();

      // Try single-argument (T extends Throwable) constructor.
      for (Constructor constructor : constructors) {
        Class[] params = constructor.getParameterTypes();
        if (params.length == 1 && params[0].isAssignableFrom(t.getClass())) {
          return constructor.newInstance(new Object[] {t});
        }
      }

      // Try single-argument (T extends String) constructor.
      for (Constructor constructor : constructors) {
        Class[] params = constructor.getParameterTypes();
        if (params.length == 1 && params[0].isAssignableFrom(String.class)) {
          T instance = constructor.newInstance(new Object[] {t.toString()});
          instance.initCause(t);
          return instance;
        }
      }

      // Try parameterless constructor, if it exists.
      for (Constructor constructor : constructors) {
        Class[] params = constructor.getParameterTypes();
        if (params.length == 0) {
          T instance = constructor.newInstance();
          instance.initCause(t);
          return instance;
        }
      }
    } catch (RuntimeException e) {
      throw e;
    } catch (Exception e) {
      // fall through, no matching constructor found.
    }

    throw new RuntimeException(
        "(No constructor found in wrapper class " + clazz.getName() + "): ", t);
  }

  /**
   * Calls {@link #wrapAs(Class, Throwable)} with the first parameter set to {@link
   * RuntimeException}.
   */
  public static RuntimeException wrapAsRuntimeException(Throwable t) {
    return wrapAs(RuntimeException.class, t);
  }

  /** Returns the current stack trace of the calling thread. */
  public static String currentStackTrace() {
    final Exception e = new Exception();
    e.fillInStackTrace();

    final StringWriter w = new StringWriter();
    final PrintWriter pw = new PrintWriter(w);
    e.printStackTrace(pw);
    pw.flush();

    return w.toString();
  }
}