com.elastisys.scale.commons.util.strings.StringUtils Maven / Gradle / Ivy

Go to download
package com.elastisys.scale.commons.util.strings;

import java.util.Map;
import java.util.Map.Entry;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;

/**
 * Convenience methods for working with {@link String}s.
 * 
 * 
 */
public class StringUtils {

	private StringUtils() {
		throw new UnsupportedOperationException(StringUtils.class.getName()
				+ " not instantiable");
	}

	/**
	 * Performs multiple string substitutions in a {@link String}.
	 * 
	 * @param string
	 * @param substitutions
	 *            A {@link Map} of substitutions to make in the form of
	 *            pattern-replacement pairs. That is,each key represents a
	 *            pattern to substitute and the corresponding value represents
	 *            the replacement string for that pattern.
	 * @return A {@link String} with all occurrences of {@code substitutions}
	 *         keys replaced by their corresponding replacement strings.
	 */
	public static String replaceAll(String string,
			Map substitutions) {
		for (Entry substitution : substitutions.entrySet()) {
			String pattern = substitution.getKey();
			String replacement = Optional.fromNullable(substitution.getValue())
					.or("null");
			string = string.replace(pattern, replacement);
		}
		return string;
	}

	/**
	 * Returns a {@link Function} that prepends a string prefix to every
	 * {@link String} it receives as input.
	 * 
	 * @param prefix
	 * @return
	 */
	public static Function prepend(String prefix) {
		return new StringPrependFunction(prefix);
	}

	/**
	 * A {@link Function} that prepends a string prefix to every {@link String}
	 * it receives as input.
	 * 
	 * 
	 */
	public static class StringPrependFunction implements
			Function {

		private final String prefix;

		/**
		 * Creates a {@link StringPrependFunction}.
		 * 
		 * @param prefix
		 *            The string to prepend to input {@link String}s.
		 */
		public StringPrependFunction(String prefix) {
			Preconditions.checkArgument(prefix != null, "null prefix");
			this.prefix = prefix;
		}

		@Override
		public String apply(String input) {
			return this.prefix + input;
		}
	}
}