wendyltan

Refactoring

What is Refactoring?

The external behavior of the system does not change while the internal structure of the system is improved.

Sometimes called "Improving the design after it has been written" or "Improving the design of existing code",the purpose is to make software easier to understand and modify

• Benefits
• Code size reduced after refactoring

wendyltan

Inner Class in Java

Defining a class inside another class is called 'Inner Class' in Java.There are four types of inner Class: Type:

• Member Inner Class
• Partial Inner Class
• Anonymous Inner Class
• Static Inner Class

Member Inner Class

wendyltan

Why is Lock better?

The limit of synchronized and the benefit of Lock

Synchronized block will only release the lock when:

• Thread executed the block and release the lock.
• Thread has an exception and JVM auto release the lock.
• Thread turn into WAITING state while using wait(),it will release the lock.

wendyltan

Java-I/O

I want to talk about Java-I/O in this gist,so I will try to be as detailed as I can.I don't really understand how each I/O class works until I learned them systematically.

Category

• I/O
  • NodeStream
    • Character

• Reader -- FileReader

wendyltan

sleep,wait and notify

What's the difference between sleep and wait?

Just see this table:

sleep	wait
belong to class Thread	belong to class Object
will not release object lock	will release object lock

wendyltan

About some Generic type knowledge in Java

Java Generic methods and generic classes enable programmers to specify, with a single method declaration, a set of related methods, or with a single class declaration, a set of related types, respectively.

Generics also provide compile-time type safety that allows programmers to catch invalid types at compile time.

Now I'm going to use a piece of code to list out basic concepts:

/**

wendyltan

Two design techniques

Use Commonality and Variability Analysis

The so-called 'CVA'

Attempts to identify:

• commonalities(generic concepts)
• variations(concrete implementations)

wendyltan

How to understand callback mechanism?

We can always see many callback functions in Java,but how does that actually work?

We know that there is five step to simulate a callback process:

• Class A implements Callback interface. /The interface has abstract function operate()/
• Class A has a member Class B's instance /b/
• Class B has a method using callback /Callback instance as parameter/doSth(Callback callback)/

wendyltan

Five ways to implement Producer and Consumer problem in Java

The ways I found out while reviewing interview note

wait() and notify()

Simply using wait and notify,with syncronized blocks

public class Test1 {
    private static Integer count = 0;

wendyltan

Design Pattern

Type

• Behavioral patterns:manage variation
• Structural patterns:integrate existing code into new design
• Creational patterns:create object,operational code gets buried behind

Facade

>Wrap up all the interface