Catch InvocationTargetException : Class Loader « Reflection « Java Tutorial

1. Java Tutorial
2. Reflection
3. Class Loader

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import static java.lang.System.err;
import static java.lang.System.out;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.Locale;

public class Deet<T> {
  private boolean testDeet(Locale l) {
    // getISO3Language() may throw a MissingResourceException
    out.format("Locale = %s, ISO Language Code = %s%n", l.getDisplayName(), l
        .getISO3Language());
    return true;
  }

  private int testFoo(Locale l) {
    return 0;
  }

  private boolean testBar() {
    return true;
  }

  public static void main(String... args) {
    if (args.length != 4) {
      err.format("Usage: java Deet <classname> <langauge> <country> <variant>%n");
      return;
    }

    try {
      Class<?> c = Class.forName(args[0]);
      Object t = c.newInstance();

      Method[] allMethods = c.getDeclaredMethods();
      for (Method m : allMethods) {
        String mname = m.getName();
        if (!mname.startsWith("test")|| (m.getGenericReturnType() != boolean.class)) {
          continue;
        }
        Type[] pType = m.getGenericParameterTypes();
        if ((pType.length != 1)|| Locale.class.isAssignableFrom(pType[0].getClass())) {
          continue;
        }

        out.format("invoking %s()%n", mname);
        try {
          m.setAccessible(true);
          Object o = m.invoke(t, new Locale(args[1], args[2], args[3]));
          out.format("%s() returned %b%n", mname, (Boolean) o);

          // Handle any exceptions thrown by method to be invoked.
        } catch (InvocationTargetException x) {
          Throwable cause = x.getCause();
          err.format("invocation of %s failed: %s%n", mname, cause.getMessage());
        }
      }

      // production code should handle these exceptions more gracefully
    } catch (ClassNotFoundException x) {
      x.printStackTrace();
    } catch (InstantiationException x) {
      x.printStackTrace();
    } catch (IllegalAccessException x) {
      x.printStackTrace();
    }
  }
}