numericvalue.java

symbman（大学作业）

public class NumericValue extends Expression {
	
	private double value;
	
	public NumericValue(double value) {
		this.value = value;
	}
	
	public double getValue() { return value; }

	public Object clone() {
		return new NumericValue(this.value);
	}

	public Expression eval() {
		return this;
	}

	public String toString() {
		return "(" + value + ")";
	}
	
	public Expression derive(Symbol s) {
		return new NumericValue(0.);
	}
	
	public Expression simplify() {
		return (Expression)this.clone();
	}
	
	public boolean equals(Expression ex) {
		if(!(ex instanceof NumericValue)) return false;
		NumericValue n = (NumericValue)ex;
		return(n.getValue()==value)?true:false;
	}
	


}