IT. Expert System.
Design patterns
State Pattern
In State pattern a class behavior changes based on its state. This type of design pattern comes under behavior pattern.
In State pattern, we create objects which represent various states and a context object whose behavior varies as its state object changes.
Implementation
We're going to create a State interface defining a action and concrete state classes implementing the State interface. Context is a class which carries a State.
StaePatternDemo, our demo class will use Context and state objects to demonstrate change in Context behavior based on type of state it is in.
Step 1
Create an interface.
Image.java
public interface State {
public void doAction(Context context);
}
Step 2
Create concrete classes implementing the same interface.
StartState.java
public class StartState implements State {
public void doAction(Context context) {
System.out.println("Player is in start state");
context.setState(this);
}
public String toString(){
return "Start State";
}
}
StopState.java
public class StopState implements State {
public void doAction(Context context) {
System.out.println("Player is in stop state");
context.setState(this);
}
public String toString(){
return "Stop State";
}
}
Step 3
Create Context Class.
Context.java
public class Context {
private State state;
public Context(){
state = null;
}
public void setState(State state){
this.state = state;
}
public State getState(){
return state;
}
}
Step 4
Use the Context to see change in behaviour when State changes.
StatePatternDemo.java
public class StatePatternDemo {
public static void main(String[] args) {
Context context = new Context();
StartState startState = new StartState();
startState.doAction(context);
System.out.println(context.getState().toString());
StopState stopState = new StopState();
stopState.doAction(context);
System.out.println(context.getState().toString());
}
}
Step 5
Verify the output.
Player is in start state
Start State
Player is in stop state
Stop State
Android Reference
Java basics
Java Enterprise Edition (EE)
Java Standard Edition (SE)
SQL
HTML
PHP
CSS
Java Script
MYSQL
JQUERY
VBS
REGEX
C
C++
C#
Design patterns
RFC (standard status)
RFC (proposed standard status)
RFC (draft standard status)
RFC (informational status)
RFC (experimental status)
RFC (best current practice status)
RFC (historic status)
RFC (unknown status)
IT dictionary
Site is optimized for mobile devices.
Downloads: 376 / 158666130. Delta: 0.01763 с