org.apache.juneau.common.internal.ArgUtils Maven / Gradle / Ivy

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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau.common.internal;

import java.text.*;

/**
 * Method argument utility methods.
 */
public class ArgUtils {

	/**
	 * Throws an {@link IllegalArgumentException} if the specified argument is null.
	 *
	 * Example:
	 * 
	 * 	import static org.apache.juneau.internal.ArgUtils.*;
	 *
	 *	public String setFoo(String foo) {
	 *		assertArgNotNull("foo", foo);
	 *		...
	 *	}
	 * 
	 *
	 * @param  The argument data type.
	 * @param name The argument name.
	 * @param o The object to check.
	 * @return The same argument.
	 * @throws IllegalArgumentException Constructed exception.
	 */
	public static final  T assertArgNotNull(String name, T o) throws IllegalArgumentException {
		assertArg(o != null, "Argument ''{0}'' cannot be null.", name);
		return o;
	}

	/**
	 * Throws an {@link IllegalArgumentException} if the specified expression is false.
	 *
	 * Example:
	 * 
	 * 	import static org.apache.juneau.internal.ArgUtils.*;
	 *
	 *	public String setFoo(List<String> foo) {
	 *		assertArg(foo != null && ! foo.isEmpty(), "'foo' cannot be null or empty.");
	 *		...
	 *	}
	 * 
	 *
	 * @param expression The boolean expression to check.
	 * @param msg The exception message.
	 * @param args The exception message args.
	 * @throws IllegalArgumentException Constructed exception.
	 */
	public static final void assertArg(boolean expression, String msg, Object...args) throws IllegalArgumentException {
		if (! expression)
			throw new IllegalArgumentException(MessageFormat.format(msg, args));
	}

	/**
	 * Throws an {@link IllegalArgumentException} if the specified value doesn't have all subclasses of the specified type.
	 *
	 * @param  The element type.
	 * @param name The argument name.
	 * @param type The expected parent class.
	 * @param value The array value being checked.
	 * @return The value cast to the specified array type.
	 * @throws IllegalArgumentException Constructed exception.
	 */
	@SuppressWarnings("unchecked")
	public static final  Class[] assertClassArrayArgIsType(String name, Class type, Class[] value) throws IllegalArgumentException {
		for (int i = 0; i < value.length; i++)
			if (! type.isAssignableFrom(value[i]))
				throw new IllegalArgumentException("Arg "+name+" did not have arg of type "+type.getName()+" at index "+i+": "+value[i].getName());
		return (Class[])value;
	}

}