add helper class that returns the size of objects

pdb-api/src/test/java/org/lucares/memory/MemoryScale.java

@@ -0,0 +1,89 @@
+package org.lucares.memory;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.lucares.utils.MiniMap;
+
+public class MemoryScale {
+	
+	public static final String A = "A";
+
+	public static void main(String[] args) {
+		System.out.println("start");
+		// warmup of classes
+		getUsedMemory();
+		Object handle =createObject();
+		
+		handle = null;
+		
+		runGc();
+		long memoryBefore = getUsedMemory();
+
+		handle = createObject();
+		
+		runGc();
+		long memoryAfter = getUsedMemory();
+		System.out.println("used memory: " + (memoryAfter - memoryBefore));
+	}
+	
+	private static Object createObject(){
+		
+		String key = "minimap";
+		switch (key) {
+		case "minimap":
+			return createMinimap();
+		case "string":
+			return createString();
+		case "linkedHashMap":
+			return createLinkedHashMap();
+		default:
+			return null;
+		}
+		
+	}
+
+	private static Object createMinimap() {
+		final MiniMap<String, String> map = new MiniMap<>();
+
+		map.put("A", "A");
+		for (int i = 0; i < 0; i++){
+			map.put(""+i, ""+i);	
+		}
+		
+		return map;
+	}
+	
+	private static String createString() {
+
+		int i= 0;
+		return ""+i;
+	}
+
+	private static Object createLinkedHashMap() {
+		final Map<String, String> map = new LinkedHashMap<>();
+
+		map.put("A", "A");
+		for (int i = 0; i < 0; i++){
+			map.put(""+i, ""+i);	
+		}
+
+		return map;
+	}
+
+	private static void runGc() {
+		for (int i = 0; i < 10; i++) {
+			System.gc();
+			try {
+				Thread.sleep(100);
+			} catch (InterruptedException e) {
+				Thread.currentThread().interrupt();
+			}
+		}
+	}
+
+	private static long getUsedMemory() {
+		return Runtime.getRuntime().totalMemory()
+				- Runtime.getRuntime().freeMemory();
+	}
+}