Dirt-simple output formatting, logback style.

Out.java

package util;

/* 
 * The MIT License (MIT)
 * 
 * Copyright (c) 2016 Broc Seib
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * 
 */

/**
 * Log to stdout, or format to string in the style of logback.
 * 
 * Example:
 * 
 *   int foo = 42;
 *   String bar = "Harry's";
 *   Out.log("I was {} when I first went to {}.", foo, bar);
 *   
 *   // output is "I was 42 when I first went to Harry's."
 *   
 * If you want to have a literal "{}" in your output, then you're wanting too much
 * from this code. If you want output to go somewhere besides stdout, you also want
 * to much from this code. This code is meant for quick and dirty testing, and not
 * as a real logging mechanism.
 *  
 * @author bseib
 *
 */
public class Out {

	static public void log(String format, Object... args) {
		System.out.println(str(format, args));
	}

	static public String str(String format, Object... args) {
		if ( null == format ) {
			return "";
		}
		int len = format.length();
		if ( len < 2 ) {
			return format;
		}
		StringBuilder buf = new StringBuilder();
		int argIndex = 0;
		int start = 0;
		for ( int i=0;i<(len-1);i++) {
			if ( (format.charAt(i) == '{') && (format.charAt(i+1) == '}') ) {
				if ( start != i ) {
					buf.append(format.substring(start, i));
				}
				if ( argIndex < args.length ) {
					buf.append((null==args[argIndex])?"null":args[argIndex].toString());
				}
				start = i + 2;
				argIndex++;
				i = i + 1; // skip checking the '}' char that we know follows
			}
		}
		if ( start < len ) {
			buf.append(format.substring(start, len));
		}
		return buf.toString();
	}

}