android简易智能容错计算器

importjava.text.DecimalFormat;
importjava.util.LinkedList;
importjava.util.Queue;
importjava.util.Scanner;
importjava.util.Stack;
publicclassTest {
privatestaticStringBuilderstr;
publicstaticvoidmain(String[] args) {
Scannercin=newScanner(System.in);
Strings=cin.next();
cin.close();
str=newStringBuilder(s);
DecimalFormatdf=newDecimalFormat("###.##############");
Stringnum=null;
try {
doubled=calculate();
if (Double.isNaN(d) ||Double.isInfinite(d)) {
System.out.println("不能除以0");
            } else {
num=df.format(d);
            }
        } catch (Exceptione) {
System.out.println("错误！");
        }
System.out.println("-0".equals(num) ?"0" : num);
    }
privatestaticdoublecalculate() {
Queue<String>q=getPostfixExpression(); // 中缀表达式转为后缀表达式returncalculatePostfixExpression(q);
    }
privatestaticdoublecalculatePostfixExpression(Queue<String>queue) {
Stack<Double>stack=newStack<>();
intlen=queue.size();
doublenum1=0.0, num2=0.0, num3=0.0;
for (inti=0; i<len; ++i) {
Strings=queue.poll();
if (!isOperator(s)) {
stack.push(Double.valueOf(s));
            } else {
num2=stack.pop();
num1=stack.pop();
switch (s) {
case"+":
num3=num1+num2;
break;
case"-":
num3=num1-num2;
break;
case"*":
num3=num1*num2;
break;
case"/":
num3=num1/num2;
break;
                }
stack.push(num3);
            }
        }
returnstack.peek();
    }
// 获得后缀表达式publicstaticQueue<String>getPostfixExpression() {
Stack<Character>stack=newStack<>();
intlen=str.length();
StringBuilderstrNum=newStringBuilder();
Queue<String>queue=newLinkedList<>();
chartemp=' ';
for (inti=0; i<len; ++i) {
temp=str.charAt(i);
if (temp>='0'&&temp<='9'||temp=='.') {
strNum.append(temp);
            } else {
if (i==0||isOperator(str.charAt(i-1) +"")) {
// 考虑负数的情况，比如乘以除以负数strNum.append(temp);
continue;
                }
queue.add(strNum.toString()); // 数字进队列strNum.setLength(0);
if (stack.isEmpty()) {
stack.push(temp);
                } else {
while (!stack.isEmpty()) {
chartop=stack.peek();
if (getPriority(top) >=getPriority(temp)) {
queue.add(top+"");
stack.pop();
                        } else {
break;
                        }
                    }
stack.push(temp);
                }
            }
        }
queue.add(strNum.toString()); // 数字进队列if (stack.isEmpty()) {
stack.push(temp);
        } else {
while (!stack.isEmpty()) {
chartop=stack.peek();
queue.add(top+"");
stack.pop();
            }
        }
returnqueue;
    }
privatestaticbooleanisOperator(Strings) {
returns.equals("+") ||s.equals("-") ||s.equals("*") ||s.equals("/");
    }
privatestaticintgetPriority(chartop) {
if (top=='+'||top=='-')
return1;
return2; // 只有加减乘除    }
}