CoreTests.java

import static it.fago.loggerstein.Loggerstein.$;
import static it.fago.loggerstein.Loggerstein.lazy;
import static it.fago.loggerstein.Loggerstein.logWith;
import static it.fago.loggerstein.Loggerstein.STD_ERR;
import static it.fago.loggerstein.Loggerstein.STD_OUT;

import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.junit.Assert.*;

/**
 * 
 * @author Stefano
 *
 */
public class CoreTest {

	private Logger logger = LoggerFactory.getLogger(Loggerstein.class);

	@Test
	public void testLazy_NewTestBean_ToString() {
		assertEquals("TESTBEAN[0,,null]", lazy(TestBean::new).toString());
	}

	@Test
	public void testLazy_NewTestBean_WithValue_ToString() {
		TestBean bean = new TestBean();
		bean.setId(1L);
		bean.setDescription("Simple Description!");
		assertEquals("TESTBEAN[1,Simple Description!,null]", lazy(bean::toString).toString());
	}

	@Test
	public void testLazy_NewTestBean_Arguments_ToString() {
		
		TestBean bean = new TestBean();
		bean.setId(1L);
		bean.setDescription("Simple Description!");
		
		String id = lazy(bean::getId).toString();
		String description = lazy(bean::getDescription).toString();
		
		assertEquals("1", id);
		assertEquals("Simple Description!", description);
	}
	
	
	@Test
	public void testLogWith_TestBean_Separated_Arguments() {

		TestBean bean = new TestBean();
		bean.setId(1L);
		bean.setDescription("Simple Description!");
		bean.setData(new String[] { "data1", "data2", "data3", "data4", "data5" });

		logWith(logger::info, "This is a TestBean: {}\nid: {}\ndesc: {}\ndata: {}", bean::toString, bean::getId,
				bean::getDescription, bean::getData);
	}

	@Test
	public void testLogWith_TestBean_Object_Argument() {

		TestBean bean = new TestBean();
		bean.setId(2L);
		bean.setDescription("Simple Description!");
		bean.setData(new String[] { "data1", "data2", "data3", "data4", "data5" });

		logWith(logger::info, "This is a TestBean: {}\nid: {}\ndesc: {}\ndata: {}", $(bean), bean::getId, bean::getDescription, bean::getData);
	}

	@Test
	public void testLogWith_TestBean_Object_Array_Argument() {

		TestBean bean1 = new TestBean();
		bean1.setId(1L);
		bean1.setDescription("Simple1!");
		bean1.setData(new String[] { "data1", "data2", "data3", "data4", "data5" });
		
		TestBean bean2 = new TestBean();
		bean2.setId(2L);
		bean2.setDescription("Simple2!");
		bean2.setData(new String[] { "data6", "data7", "data8", "data9", "data10" });
		
		TestBean bean3 = new TestBean();
		bean3.setId(3L);
		bean3.setDescription("Simple3!");
		bean3.setData(new String[] { "data11", "data12", "data13", "data14", "data15" });

		logWith(logger::info, "We now have more TestBean:\n{}\n{}\n{}", $(bean1,bean2,bean3));
	}
	
	@Test
	public void testLogWith_TestBean_STD_OUT(){
		
		TestBean bean = new TestBean();
		bean.setId(9L);
		bean.setDescription("Logging with STD_OUT");
		bean.setData(new String[] { "data1", "data2", "data3", "data4", "data5" });
		
		logWith(STD_OUT, "This is a TestBean: %s\nid: %s\ndesc: %s\ndata: %s", $(bean), bean::getId, bean::getDescription, bean::getData);

	}

	@Test
	public void testLogWith_TestBean_STD_ERR(){
		
		TestBean bean = new TestBean();
		bean.setId(10L);
		bean.setDescription("Logging with STD_ERR");
		bean.setData(new String[] { "data1", "data2", "data3", "data4", "data5" });
		
		logWith(STD_ERR, "This is a TestBean: %s\nid: %s\ndesc: %s\ndata: %s", $(bean), bean::getId, bean::getDescription, bean::getData);

	}

	/**
	 * 
	 * @author Stefano
	 *
	 */
	public static class TestBean {
		//
		private String description="";
		//
		private long id;
		//
		private String[] data;

		public String getDescription() {
			return description;
		}

		public void setDescription(String description) {
			this.description = description;
		}

		public long getId() {
			return id;
		}

		public void setId(long id) {
			this.id = id;
		}

		public String[] getData() {
			return data;
		}

		public void setData(String[] data) {
			this.data = data;
		}

		public String toString() {
			return "TESTBEAN[" + id + "," + description + "," + String.valueOf(data) + "]";
		}

	}// END

}//END

Loggerstein.java

package it.fago.loggerstein;

import static java.lang.String.valueOf;
import static java.util.Arrays.stream;

import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.function.Supplier;


/**
 *
 * LOGGERSTEIN - A Monstruos Facade for Your Logging System!
 *
 */
public final class Loggerstein {
	//
	private static final String[] SURROGATE_FOR_NULL_ARRAY = {};
	//
	private static final String SURROGATE_FOR_NULL = "";
	//
	private static final Supplier<?>[] SURROGATE_FOR_NULL_ARRAY_SUP =  new Supplier<?>[]{()->SURROGATE_FOR_NULL_ARRAY};
	//
	public static final BiConsumer<String, Object[]> STD_OUT = System.out::printf;
	//
	public static final BiConsumer<String, Object[]> STD_ERR = System.err::printf;
	//
	private static final Function<Object,Supplier<?>> TO_SUPPLIER = object->()->object;

	//======================================================================
	//
	//
	//
	//======================================================================
	
	public static final  Object lazy(final Supplier<?> arg) {
		return arg == null ? 
			SURROGATE_FOR_NULL : new Object() {
			public final String toString() {
				return valueOf(arg.get());
			}
		};
	}

	public static final Object[] lazy(final Supplier<?>... args) {
		return args == null ? 
				SURROGATE_FOR_NULL_ARRAY : 
				stream(args)
				  .map(Loggerstein::lazy)
				.toArray();
	}
	
	//======================================================================
	//
	//
	//
	//======================================================================
	
	public static final Supplier<?> $(final Object arg) {
		return arg == null ? 
				()->SURROGATE_FOR_NULL : 
				()->arg;
	}

	public static final Supplier<?>[] $(final Object ... args) {
		return args == null?
		   SURROGATE_FOR_NULL_ARRAY_SUP:
		   stream(args)
				.map(TO_SUPPLIER)
			    .toArray(Supplier[]::new);
	}

	//======================================================================
	//
	//
	//
	//======================================================================
	
	public static final void logWith(
			final BiConsumer<String, Object[]> activity,
			final String msg,
			final Supplier<?>... args) {
		activity.accept(msg, lazy(args));
	}
	
}// END