import java.util.ArrayList;
import java.util.List;
public class MathString {
public static void main(String[] args){
String press = "12*12.22-7*(23.45-(-2))+(12-34)";
press = press.replaceAll("[\\[\\{]", "(").replaceAll("[\\]\\}]", ")");
System.out.println(parseString(press));
}
public static String parseString(String press){
int lasc = press.lastIndexOf("(");
if(lasc==-1){
return String.valueOf(addString(press));
}
String firstKHString = press.substring(0,lasc);
String lastFKHString = press.substring(lasc+1);
//System.out.println("firstKHString---"+firstKHString);
//System.out.println("lastFKHString---"+lastFKHString);
int firc = lastFKHString.indexOf(")");
lastFKHString = press.substring(firc+lasc+2);
//System.out.println("lastFKHString---"+lastFKHString);
String currentPress = press.substring(lasc+1,firc+lasc+1);
//System.out.println(currentPress);
return parseString(firstKHString+addString(currentPress)+lastFKHString);
}
public static double addString(String press){
//System.out.println(press);
press = repAddString(press);
press = repString(press);
//System.out.println(press);
String[] numbers = press.split("[\\+]");
double number = 0;
List<String> fhs = getFHAdd(press);
for(int i=0 ; i<numbers.length; i++ ){
String curNum = numbers[i];
//System.out.println(curNum);
if(curNum.equals("")){
curNum="0";
}
if(fhs.get(i).equals("+")){
number = number + mathString(curNum);
}else if(fhs.get(i).equals("-")){
number = number - mathString(curNum);
}
}
return number;
}
public static double mathString(String press){
/*int firstCH = press.indexOf("*");
int firstC = press.indexOf("/");
if(firstCH == -1 && firstC == -1){
return Double.parseDouble(press);
}
int firstindex = firstC < firstCH ? firstC : firstCH;
*/
press = repAddString(press);
String[] numbers = press.split("[\\*\\/]");
List<String> fhs = getFH(press);
double result = 1;
for(int i=0 ; i<numbers.length; i++){
if(fhs.get(i).equals("*")){
result = result * Double.parseDouble(numbers[i]);
}else if(fhs.get(i).equals("/")){
if(Double.parseDouble(numbers[i])==0){
throw new ArithmeticException("表达式中被除数有空值!");
}
result = result / Double.parseDouble(numbers[i]);
}
}
return result;
}
public static String repAddString(String press){
return press.replace("++", "+").replace("--", "+").replace("+-", "-").replace("-+", "-");
}
public static String repString(String press){
StringBuffer sb = new StringBuffer();
char ch = 0;
for(char c:press.toCharArray()){
if(c=='-'&&'/'!=ch&&'*'!=ch){
sb.append("+");
}
ch = c;
sb.append(c);
}
return sb.toString();
}
public static List<String> getFH(String press){
char[] chars = press.toCharArray();
List<String> fhs = new ArrayList<String>();
fhs.add("*");
for(char c : chars){
if(c=='*' || c=='/'){
fhs.add(String.valueOf(c));
}
}
return fhs;
}
public static List<String> getFHAdd(String press){
char[] chars = press.toCharArray();
List<String> fhs = new ArrayList<String>();
fhs.add("+");
for(char c : chars){
if(c=='+'){
fhs.add(String.valueOf(c));
}
}
return fhs;
}
}
posted on 2011-07-01 10:09
墙头草 阅读(1416)
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