Pseudo code design cache for interview questions

Package com. Threadlearn.test;
Import java.util.*;
Import Java.util.concurrent.locks.ReadWriteLock;
Import Java.util.concurrent.locks.ReentrantReadWriteLock;
Interview questions, design a caching system; Use pseudocode to implement public
class Cachedemo {

	//Storage object Container
	private map<string,object> Map = new Hashmap<string,object> ();
	Read and write lock
	private Readwritelock RWL = new Reentrantreadwritelock ();
	
	Public Object GetObject (String key) {
		
		Object obj = null;
		Rwl.readlock (). Lock ();
		try{
			
			if (Map.get (key) ==null) {
				
				rwl.readlock (). Unlock ();
				Rwl.writelock (). Lock ();
				
				try{
					obj = Readfromdb ();
					
				} finally{
					rwl.writelock (). Unlock ();
				}
				Rwl.readlock (). Lock ();
				
			} else{
				
				obj = map.get (key);
			}
		catch (Exception ex) {
			
			ex.printstacktrace ();
		} finally{
			
			rwl.readlock (). Unlock ();
		}
		return obj;
	}
	
	The public Object Readfromdb () {
		
		//reads data from the database, the code is slightly return
		null;
	}
}