Java计算器实现(逆波兰式).docx

package hfw.util;import java.util.ArrayDeque;import java.util.Deque;/* * *逆波兰式 *总结，java版的Eval：逆波兰和动态编译，推荐用动态编译，因为逆波兰式不认识- 4，只认识-4 *author zyh */public class RNP /* * 运算数 */private static Deque operationNum = new ArrayDeque();/* * 运算符 */private static Deque operator = new ArrayDeque();/* * 将表达式转换为逆波兰式 * param expression * return */private static void str2Rnp(String expression)operationNum.clear();operator.clear();int index = 0;for(int i=0;i0)RNP.operationNum.push(operationNum.trim();index = i+1;String operator = c+;/如果操作符是(，直接入栈if(=c)RNP.operator.push(operator);/如果操作符是)，将(操作符之后的全部出栈，入栈操作数，( )舍弃else if()=c)while(true)String o = RNP.operator.pollFirst();if(o=null | (.equals(o)break;RNP.operationNum.push(o);/如果操作符是+-*/elseString o = RNP.operator.peekFirst();if(o= null)/如果操作符栈为空，操作符直接入栈RNP.operator.push(operator);else char operator2 = o.charAt(0);/比较操作符，和操作符栈首 的大小，如果操作符大，直接入栈if(operator2=( | operator2=) | orderOperator(c,operator2)RNP.operator.push(operator);/如果操作符栈首大，将操作符栈小于操作符的全部出栈，入栈操作数，最后改操作符入栈elsewhile(true)if(o=null | o.charAt(0) =(| o.charAt(0) =)break;if(orderOperator(c, o.charAt(0)break;o = RNP.operator.pollFirst();RNP.operationNum.push(o);o = RNP.operator.peekFirst();RNP.operator.push(operator);String operationNum = expression.substring(index);if(operationNum.trim().length()0)RNP.operationNum.push(operationNum.trim();while(RNP.operator.size()0)RNP.operationNum.push(RNP.operator.pollFirst();/RNP.operationNum.addAll(RNP.operator);/判断一个字符是否为运算符 private static boolean isOperator(char c) return c=+ | c=- | c=* | c=/; /判断运算符顺序，true表示运算符operator1operator2,false表示相等或小于 private static boolean orderOperator(char operator1, char operator2) if(operator1=* | operator1=/) & (operator2=+ | operator2=-) return true; return false; /* * 计算逆波兰式的值 * return */ private static double countRnp()while(RNP.operationNum.size()0)String s = RNP.operationNum.pollLast();/如果是操作符，取出栈顶的两个操作数，直接运算char operator = s.charAt(0);if(s.length()=1 & isOperator(operator)String a = RNP.operator.pollFirst();String b = RNP.operator.pollFirst();if(+=operator)double result = Double.parseDouble(b)+Double.parseDouble(a);RNP.operator.push(result+);else if(-=operator)double result = Double.parseDouble(b)-Double.parseDouble(a);RNP.operator.push(result+);if(*=operator)double result = Double.parseDouble(b)*Double.parseDouble(a);RNP.operator.push(result+);if(/=operator)double result = Double.parseDouble(b)/Double.parseDouble(a);RNP.operator.push(result+);/如果是操作数，入栈elseRNP.operator.push(s);double result = Double.parseDouble(RNP.operator.pollLast();return result;/* * 计算逆波兰式的值(整数) * return */ private static int intRnp()while(RNP.operationNum.size()0)String s = RNP.operationNum.pollLast();/如果是操作符，取出栈顶的两个操作数，直接运算char operator = s.charAt(0);if(s.length()=1 & isOperator(operator)String a = RNP.operator.pollFirst();String b = RNP.operator.pollFirst();if(+=operator)int result = Integer.parseInt(b)+Integer.parseInt(a);RNP.operator.push(result+);else if(-=operator)int result = Integer.parseInt(b)-Integer.parseInt(a);RNP.operator.push(result+);if(*=operator)int result = Integer.parseInt(b)*Integer.parseInt(a);RNP.operator.push(result+);if(/=operator)int result = Integer.parseInt(b)/Integer.parseInt(a);RNP.operator.push(result+);/如果是操作数，入栈elseRNP.operator.push(s);int result = Integer.parseInt(RNP.operator.pollLast();return result;/* * 计算表达式的值 * param expression * return */public static double calculate(String expression)trystr2Rnp(expression);return countRnp();catch(Exception e)e.printStackTrace();System.out.println(请检查表达式);return 0.0;/* * 计算表达式的值(整数) * param expression * return */public static int intCalculate(String expression)trystr2Rnp(expression);return intRnp();catch(Exception e)e.printStackTrace();System.out.println(请检查表达式);return 0;public