The project uses user-defined calculation formulas for calculation, so that the four-character string calculation analysis is required. The following is a class of four-character string formulas for calculation analysis and calculation tools. Students who need it can refer to it.
The tool class is as follows:
package ;
import ;
import ;
/**
* @author zhangwenchao
* @since 2016-08-26
* Formula calculation tool class
*/
public class FormulaCalculator {
private static boolean isRightFormat = true;
public static double getResult(String formula){
double returnValue = 0;
try{
returnValue = doAnalysis(formula);
}catch(NumberFormatException nfe){
("The formula format is incorrect, please check:" + formula);
}catch(Exception e){
();
}
if(!isRightFormat){
("The formula format is incorrect, please check:" + formula);
}
return returnValue;
}
private static double doAnalysis(String formula){
double returnValue = 0;
LinkedList<Integer> stack = new LinkedList<Integer>();
int curPos = 0;
String beforePart = "";
String afterPart = "";
String calculator = "";
isRightFormat = true;
while(isRightFormat&&(('(') >= 0||(')') >= 0)){
curPos = 0;
for(char s : ()){
if(s == '('){
(curPos);
}else if(s == ')'){
if(() > 0){
beforePart = (0, ());
afterPart = (curPos + 1);
calculator = (() + 1, curPos);
formula = beforePart + doCalculation(calculator) + afterPart;
();
break;
}else{
("There is an unclosed closing bracket!");
isRightFormat = false;
}
}
curPos++;
}
if(() > 0){
("There are unclosed opening brackets!");
break;
}
}
if(isRightFormat){
returnValue = doCalculation(formula);
}
return returnValue;
}
private static double doCalculation(String formula) {
ArrayList<Double> values = new ArrayList<Double>();
ArrayList<String> operators = new ArrayList<String>();
int curPos = 0;
int prePos = 0;
int minus = 0;
for (char s : ()) {
if ((s == '+' || s == '-' || s == '*' || s == '/') && minus !=0 && minus !=2) {
(((prePos, curPos).trim()));
("" + s);
prePos = curPos + 1;
minus = minus +1;
}else{
minus =1;
}
curPos++;
}
(((prePos).trim()));
char op;
for (curPos = 0; curPos <= () - 1; curPos++) {
op = (curPos).charAt(0);
switch (op) {
case '*':
(curPos, (curPos) * (curPos + 1));
(curPos + 1);
(curPos + 1);
(curPos);
curPos = -1;
break;
case '/':
(curPos, (curPos) / (curPos + 1));
(curPos + 1);
(curPos + 1);
(curPos);
curPos = -1;
break;
}
}
for (curPos = 0; curPos <= () - 1; curPos++) {
op = (curPos).charAt(0);
switch (op) {
case '+':
(curPos, (curPos) + (curPos + 1));
(curPos + 1);
(curPos + 1);
(curPos);
curPos = -1;
break;
case '-':
(curPos, (curPos) - (curPos + 1));
(curPos + 1);
(curPos + 1);
(curPos);
curPos = -1;
break;
}
}
return (0).doubleValue();
}
public static void main(String[] args) {
(("3-(4*5)+5"));
(("7/2-(-4)"));
(("1287763200000-1276272000000")/(3600*24*1000));
}
}
Supports four-character operations and supports negative number analysis.
Attached, the decimal data reserved number of digits tool class,
package ;
import ;
/**
* @author zhangwenchao
* Decimal point Tools for precision
*/
public class SetNumberPrecision {
public static String setNumberPrecision(double x,int Number){
String p="#########0";
if(Number==0){
p="#########0";
}else{
p="#########0.";
for(int i=0;i<Number;i++){//The clever use of for p=p+"0";
}
}
DecimalFormat f = new DecimalFormat(p);
String s = (x).toString();
return s;
}
}
The above method of implementing the four-character formula analysis tool class for Java strings is all the content I share with you. I hope you can give you a reference and I hope you can support me more.