Design pattern Start-state mode

State mode

First, the definition:

Allows change of behavior when an object's internal state changes, implementing state changes

Second, the role

The main solution is that when the conditional expression of a state transition is too complex, the judgment of the state is transferred to a series of classes of different states, simplifying the complex judgment.

Three, class diagram:

Iv. Realization OF

The 1.work class is used to implement the transformation state, state judgment, and the program that runs the corresponding state is also the interface that the user calls.

 Public classWork {State state ;  PublicWork () { This. State =NewFornoon (); }    Private inthour;  Public intGethour () {return  This. hour; }     Public voidSethour (inthour) {         This. Hour =hour; }     Public voiddoWork () { This. State.dowork ( This); }     Public voidsetState (state state) { This. State =State ; }}

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2.state class actual operation, call the work of the state switch

 Public Abstract class State {    publicabstractvoid  doWork;}

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Implementation class of 3.state

 Public classAfternoonextendsState {@Override Public voiddoWork (Work work) {if(Work.gethour () > 12) {System.out.println ("In the Afternoon"); }        Else{work.setstate (NewFornoon ());        Work.dowork (); }    }} Public classFornoonextendsState {@Override Public voiddoWork (Work work) {if(Work.gethour () < 12) {System.out.println ("In the Morning"); }        Else{work.setstate (Newafternoon ());        Work.dowork (); }    }}

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4. Customer Class Test class

 Public class Client {    publicstaticvoid  main (string[] args)    {        new work ();        Work.sethour (+);        Work.dowork ();        Work.sethour (+);        Work.dowork ();    }}

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Design pattern Start-state mode