简单工厂模式

public interface IProgram
{
    Double getResult(Double a,Double b);
}



public class AddProgram implements IProgram
{
    public Double getResult( Double a, Double b )
    {
        return a+b;
    }

}

public class OperateProgram
{
    public static IProgram getProgram(char c){
        IProgram iProgram = null ;
        switch ( c )
        {
            case '+':
                iProgram = new AddProgram();
                break;
            default:
                break;
        }
        return iProgram;
    }
}

public class GetResult
{
    public static void main( String[] args )
    {
        // TODO Auto-generated method stub
        IProgram iProgram = OperateProgram.getProgram( '+' );
        Double d = iProgram.getResult( 1.2, 2.2 );
        System.out.println(d);
    }

}