java 实现简单计算器算法

import java.util.Vector;

public class Test {

static String str1 = "1+2*3-4/2+5*6*7-8+9*10";

static int value = 0;

static Vector dataVector = null;

static Vector opVector = null;

public static void main(String args[])

{

splitStr();

printVector();

value = doCalc();

System.out.println("");

System.out.println("value = " + value);

}

public static void splitStr()

{

dataVector = new Vector();

opVector = new Vector();

int strLen = str1.length();

int beginIdx = 0;

int endIdx = 0;

int length = 1;

char c1 = ';';

while (beginIdx < strLen)

{

length = 1;

endIdx = beginIdx + 1;

c1 = str1.charAt(beginIdx);

if (c1 == '+'

|| c1 == '-'

|| c1 == '*'

|| c1 == '/')

{

opVector.addElement(str1.substring(beginIdx, endIdx));

beginIdx += length;

}

else 

{

if (endIdx <= (strLen - 1))

{

while (str1.charAt(endIdx) != '+'

&& str1.charAt(endIdx) != '-'

&& str1.charAt(endIdx) != '*'

&& str1.charAt(endIdx) != '/')

{

endIdx++;

length++;

if (endIdx >= strLen)

break;

}

dataVector.addElement(str1.substring(beginIdx, endIdx));

beginIdx += length;

}

else

{

dataVector.addElement(str1.substring(beginIdx, endIdx));

beginIdx += length;

}

}

}

}

public static void printVector()

{

int len = dataVector.size();

int i = 0;

for (; i< len; ++i)

{

if (0 == i)

System.out.print(" " + dataVector.get(i));

else

System.out.print(", " + dataVector.get(i));

}

System.out.println("");

len = opVector.size();

i = 0;

for (; i< len; ++i)

{

if (0 == i)

System.out.print(" " + opVector.get(i));

else

System.out.print(", " + opVector.get(i));

}

}

public static int doCalc()

{

int multiDivOpCnt = 0;

for (int i = 0; i < opVector.size(); ++i)

{

char op = opVector.get(i).toString().charAt(0);

if (op == '*' || op == '/')

multiDivOpCnt++;

}

int opIdx = 0;

char op = ';';

int tmpData = 0;

int opSize = opVector.size();

while (opSize > 0)

{

op = opVector.get(opIdx).toString().charAt(0);

if (multiDivOpCnt > 0)

{

if (op == '*')

{

tmpData = Integer.parseInt(dataVector.get(opIdx).toString()) * Integer.parseInt(dataVector.get(opIdx + 1).toString());

opVector.remove(opIdx);

multiDivOpCnt--;

dataVector.remove(opIdx + 1);

dataVector.remove(opIdx);

dataVector.insertElementAt(String.valueOf(tmpData), opIdx);

opSize = opVector.size();

}

else if (op == '/')

{

tmpData = Integer.parseInt(dataVector.get(opIdx).toString()) / Integer.parseInt(dataVector.get(opIdx + 1).toString()); 

opVector.remove(opIdx);

multiDivOpCnt--;

dataVector.remove(opIdx + 1);

dataVector.remove(opIdx);

dataVector.insertElementAt(String.valueOf(tmpData), opIdx);

opSize = opVector.size();

}

else

{

opIdx++;

}

}

else 

{

opIdx = 0;

if (op == '+')

{

tmpData = Integer.parseInt(dataVector.get(opIdx).toString()) + Integer.parseInt(dataVector.get(opIdx + 1).toString());

opVector.remove(opIdx);

dataVector.remove(opIdx + 1);

dataVector.remove(opIdx);

dataVector.insertElementAt(String.valueOf(tmpData), opIdx);

opSize = opVector.size();

}

else if (op == '-')

{

tmpData = Integer.parseInt(dataVector.get(opIdx).toString()) - Integer.parseInt(dataVector.get(opIdx + 1).toString()); 

opVector.remove(opIdx);

dataVector.remove(opIdx + 1);

dataVector.remove(opIdx);

dataVector.insertElementAt(String.valueOf(tmpData), opIdx);

opSize = opVector.size();

}

}

if (0 == multiDivOpCnt)

opIdx = 0;

}

return Integer.parseInt(dataVector.get(0).toString());

}

}