高手请指点,一个计算器程序
我刚刚学java两个星期,试着写了一个计算器,通不过编译,问题好象出在Stack类上,请高手指点,在线等候.import java.util.*;
class Calculator
{
private String expression="0";
public Calculator(){}
public Calculator(String expression)
{
this.expression = expression;
}
public void setExpression(String expression)
{
this.expression = expression;
}
private char compare(char operation1,char operation2)throws ExpressionException
{
char ch;
switch(operation1)
{
case '+':
case '-':
if(operation2=='+'||operation2=='-'||operation2==')'||operation2=='=')
ch='<';
else
ch='>';
break;
case '*':
case '/':
if(operation2=='(')
ch='<';
else
ch='>';
break;
case '(':
if(operation2==')')
ch='=';
else
ch='<';
break;
case '=':
if(operation2=='=')
ch='=';
else
ch='<';
break;
default:
throw new ExpressionException("表达式错误，请更正.");
}
return ch;
}
private void checkExpression()throws ExpressionException
{
int ilength = expression.length();
for(int i=0;i<ilength;i++)
{
char ch = expression.charAt(i);
if(ch!='+'&&ch!='-'&&ch!='*'&&ch!='/'&&ch!='('&&ch!=')'&&ch!='='&&(ch<48||ch>57))
throw new ExpressionException("表达式错误，请更正.");
}
}
private boolean isOperation(char cOperation)
{
if(cOperation=='+'||cOperation=='-'||cOperation=='*'||cOperation=='/'||cOperation=='('
||cOperation==')'||cOperation=='=')
return true;
return false;
}
private int calculate(int operator1,char cOperation,int operator2)
{
switch(cOperation)
{
case '+':
return operator1+operator2;
case '-':
return operator1-operator2;
case '*':
return operator1*operator2;
case '/':
return operator1/operator2;
}
}
private void showResult(int result)
{
System.out.println("表达式的值为:"+result);
}
private void showExpression()
{
System.out.println("表达式:"+expression);
}
public void run()
{
showExpression();
try
{
checkExpression();
}
catch(ExpressionException e)
{
e.printStackTrace();return;
}
Stack operationStack = new Stack();
Stack operatorStack = new Stack();
operationStack.push('=');
while(!operationStack.empty())
{
int i=0;
if(Character.isDigit(expression.charAt(i)))
{
int j=i;
do
{
j++;
}while(Character.isDigit(expression.charAt(j)));
int operator = Integer.parseInt(expression.substring(i,j));
operatorStack.push(operator);
i=j;
}
else
{
char operation2 = expression.charAt(i);
char relation;
try
{
relation = compare(operationStack.peek(),operation2);
}
catch(ExpressionException e)
{
e.printStackTrace();return;
}
switch(relation)
{
case '<':
operationStack.push(operation2);
i++;break;
case '=':
operationStack.pop();i++;break;
case '>':
char operation1 = operationStack.pop();
int operator2 = operatorStack.pop();
int operator1 = operatorStack.pop();
operatorStack.push(calculate(operator1,operation1,operator2));
break;
}
}
}
showResult(operatorStack.pop());
}
}
class ExpressionException extends Exception
{
public ExpressionException(String msg)
{
super(msg);
}
}
class CalculatorTest
{
public static void main(String [] args)
{
Calculator calculator = new Calculator(args[0]);
calculator.run();
}
}
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