calculatorcommand.java

设计模式代码

//
public class CalculatorCommand implements Command{
	char operator;   //
	int operand;       //
	Calculator calculator;  //
	private int total=0;
	
	public CalculatorCommand(Calculator calculator,char operator,int operand){
		this.calculator=calculator;
		this.operator=operator;
		this.operand=operand;
	}
	
	public void Execute(){
		//
		//
		calculator.Operation(operator,operand);
	}
	public void UnExecute(){
		//
		//
		//
		calculator.Operation(Undo(operator),operand);
	}
	//
	private char Undo(char operator){
		char undo='E';
		switch(operator){
			case '+': total-=operand;break;
			case '-': total+=operand;break;
			case '*': total/=operand;break;
			case '/': total*=operand;break;
		}
		return undo;
	}
}