我正在为一个学校项目编写一个程序，该程序读取化学式并确定质量和百分比组成。我正在尝试编写方法来读取公式，并根据元素在公式中出现的频率创建一个包含符号的数组。但是，每当我测试公式读取器方法时，我得到的字符串索引超出范围错误。有人能告诉我我做错了什么吗？
//http://www.ptable.com/ was the source for information on elements
//knowledgedoor.com/ was the source for charges of elements not listed on common ion sheet and not having a charge based on what group it was. I used the one that said more common. Did not use if said with disagreement
// If an element had multiple charges from common ion sheet, I created multiple objects with similar attributes except charge. Object was named using atomic symbol and a number following corresponding to roman numeral
import java.util.Scanner;
public class compositionMassMolesAtoms {
public static double avoNum = (6.02 * Math.pow(10,23));
static Element H = new Element(1,1,1, "Hydrogen", "H", 1.007, 1, "nonmetal");
static Element He = new Element(1,18,2, "Helium", "He", 4.002, 0, "nonmetal");
static Element Li = new Element(2,1,3,"Lithium", "Li", 6.941, 1, "metal");
//period 2
static Element Be = new Element(2,2,4,"Beryllium", "Be", 9.012, 2, "metal");
static Element B = new Element(2,13,5, "Boron", "B", 10.811, 3, "metalloid");
static Element C = new Element(2,14,6, "Carbon", "C", 12.0107, 4, "metal");
static Element N = new Element(2,15,7, "Nitrogen", "N", 14.007, -3, "nonmetal");
static Element O = new Element(2,16,8, "Oxygen", "O", 15.9994, -2, "nonmetal");
static Element F = new Element(2,17,9, "Fluorine", "F", 18.998, -1, "nonmetal");
static Element Ne = new Element(2,18,10, "Neon", "Ne", 20.1797, 0, "nonmetal");
// period 3
static Element Na = new Element(3,1,11, "Sodium", "Na", 22.989, 1, "metal");
static Element Mg = new Element(3,2,12, "Magnesium", "Mg", 24.305, 2, "metal");
static Element Al = new Element(3,13,13, "Aluminum", "Al", 26.981, 3, "metals");
static Element Si = new Element(3,14,14, "Silicon", "Si", 28.085, 4, "metalloid");
static Element P = new Element(3,15,15, "Phosphorous", "P", 30.973, -3, "nonmetal");
static Element S = new Element(3,16,16, "Sulfur", "S", 32.06, -2, "nonmetal");
static Element Cl = new Element(3,17,17, "Chlorine", "Cl", 35.45, -1, "nonmetal");
static Element Ar = new Element(3,18,18, "Argon", "Ar", 39.948, 0, "nonmetal");
//period 4
static Element K = new Element(4,1,19, "Potassium", "K", 39.0983, 1, "metal");
static Element Ca = new Element(4,2,20, "Calcium", "Ca", 40.078, 2, "metal");
static Element Sc = new Element(4,3,21, "Scandium", "Sc", 44.955, 3, "metal");
static Element Ti = new Element(4,4,22, "Titanium", "Ti", 47.867, 4, "metal");
static Element V = new Element(4,5,23, "Vanadium", "V", 50.9415, 5, "metal");
static Element Cr2 = new Element(4,6,24, "Chromium", "Cr", 51.9961, 2, "metal");
static Element Cr3 = new Element(4,6,24, "Chromium", "Cr", 51.9961, 3, "metal");
static Element Mn2 = new Element(4,7,25, "Manganese", "Mn", 54.938, 2, "metal");
static Element Mn3 = new Element(4,7,25, "Manganese", "Mn", 54.938, 3, "metal");
static Element Mn4 = new Element(4,7,25, "Manganese", "Mn", 54.938, 4, "metal");
static Element Fe2 = new Element(4,8,26, "Iron", "Fe", 55.845, 2, "metal");
static Element Fe3 = new Element(4,8,26, "Iron", "Fe", 55.845, 3, "metal");
static Element Co2 = new Element(4,9,27, "Cobalt", "Co", 58.933, 2, "metal");
static Element Co3 = new Element(4,9,27, "Cobalt", "Co", 58.933, 3, "metal");
static Element Ni2 = new Element(4,10,28, "Nickel", "Ni", 58.6934, 2, "metal");
static Element Ni3 = new Element(4,10,28, "Nickel", "Ni", 58.6934, 3, "metal");
static Element Cu1 = new Element(4,11,29, "Copper", "Cu", 63.546, 1, "metal");
static Element Cu2 = new Element(4,11,29, "Copper", "Cu", 63.546, 2, "metal");
static Element Zn = new Element(4,12,30, "Zinc", "Zn", 65.38, 2, "metal");
static Element Ga = new Element(4,13,31, "Gallium", "Ga", 69.723, 3, "metal");
static Element Ge = new Element(4,14,32, "Germanium", "Ge", 72.63, 4, "metalloid");
static Element As = new Element(4,15,33, "Arsenic", "As", 74.9216, -3, "metalloid");
static Element Se = new Element(4,16,34, "Selenium", "Se", 78.96, -2, "nonmetal");
static Element Br = new Element(4,17,35, "Bromine", "Br", 79.904, -1, "nonmetal");
static Element Kr = new Element(4,18,36, "Krypton", "Kr", 83.798, 0, "nonmetal");
//period 5
static Element Rb = new Element(5,1,37, "Rubidium", "Rb", 85.4678, 1, "metal");
static Element Sr = new Element(5,2,38, "Strontium", "Sr", 87.62, 2, "metal");
static Element Y = new Element(5,3,39, "Yttrium", "Y", 88.90585, 3, "metal");
static Element Zr = new Element(5,4,40, "Zirconium", "Zr", 91.224, 4, "metal");
static Element Nb = new Element(5,5,41, "Niobium", "Nb", 92.90638, 5, "metal");
static Element Mo = new Element(5,6,42, "Molybdenum", "Mo", 95.96, 6, "metal");
static Element Tc = new Element(5,7,43, "Technetium", "Tc", 98, 4, "metal");
static Element Ru = new Element(5,8,44, "Ruthenium", "Ru", 101.07, 3, "metal");
static Element Rh = new Element(5,9,45, "Rhodium", "Rh", 102.90550, 3, "metal");
static Element Pd = new Element(5,10,46, "Palladium", "Pd", 106.43, 2, "metal");
static Element Ag = new Element(5,11,47, "Silver", "Ag", 107.8682, 1, "metal");
// charges after this point are not accurate, as they are just set to one.
// need to go back and correct charges
static Element Cd = new Element(5,12,48, "Cadmium", "Cd", 112.411, 1, "metal");
static Element In = new Element(5,13,49, "Indium", "In", 114.818, 1, "metal");
static Element Sn = new Element(5,14,50, "Tin", "Sn", 118.710, 1, "metal");
static Element Sb = new Element(5,15,51, "Antimony", "Sb", 121.760, 1,"metalloid");
static Element Te = new Element(5,16,52, "Tellurium", "Te", 127.60, 1, "metalloid");
static Element I = new Element(5,17,53, "Iodine", "I", 126.90, 1, "nonmetal");
static Element Xe = new Element(5,18,54, "Xenon", "Xe", 131.293, 1, "nonmetal");
// period 6
static Element Cs = new Element(6,1,55, "Caesium", "Cs", 132.90, 1, "metal");
static Element Ba = new Element(6,2,56, "Barium", "Ba", 137.327, 1, "metal");
// Lanthanoids
static Element La = new Element(8,1,57, "Lanthanum", "La", 138.90, 1, "metal");
static Element Ce = new Element(8,2,58, "Cerium", "Ce", 140.116, 1, "metal");
static Element Pr = new Element(8,3,59, "Praseodymium", "Pr", 140.90, 1, "metal");
static Element Nd = new Element(8,4,60, "Neodymium", "Nd", 144.242, 1, "metal");
static Element Pm = new Element(8,5,61, "Promethium", "Pm", 145, 1, "metal");
static Element Sm = new Element(8,6,62, "Samarium", "Sm", 150.36, 1, "metal");
static Element Eu = new Element(8,7,63, "Europium", "Eu", 151.964, 1, "metal");
static Element Gd = new Element(8,8,64, "Gadolinium", "Gd", 157.25, 1, "metal");
static Element Tb = new Element(8,9,65, "Terbium", "Tb", 158.92, 1, "metal");
static Element Dy = new Element(8,10,66, "Dysprosium", "Dy", 162.5, 1, "metal");
static Element Ho = new Element(8,11,67, "Holmium", "Ho", 164.93, 1, "metal");
static Element Er = new Element(8,12,68, "Erbium", "Er", 167.259, 1, "metal");
static Element Tm = new Element(8,13,69, "Thulium", "Tm", 168.93, 1, "metal");
static Element Yb = new Element(8,14,70, "Ytterbium", "Yb", 173.054, 1, "metal");
static Element Lu = new Element(8,15,71, "Lutetium", "Lu", 174.9668, 1, "metal");
// End of lanthanoids, period 6
static Element Hf = new Element(6,4,72, "Hafnium", "Hf", 178.49, 1, "metal");
static Element Ta = new Element(6,5,73, "Tantalum", "Ta", 180.94, 1, "metal");
static Element W = new Element(6,6,74, "Tungsten", "W", 183.84, 1, "metal");
static Element Re = new Element(6,7,75, "Rhenium", "Re", 186.207, 1, "metal");
static Element Os = new Element(6,8,76,"Osmium", "Os", 190.23, 1, "metal");
static Element Ir = new Element(6,9,77, "Iridium", "Ir", 192.217, 1, "metal");
static Element Pt = new Element(6,10,78, "Platinum", "Pt", 195.084, 1, "metal");
static Element Au = new Element(6,11,79, "Gold", "Au", 196.96,1,"metal");
static Element Hg = new Element(6,12,80,"Mercury", "Hg", 200.59, 1, "metal");
static Element Tl = new Element(6,13,81, "Thallium", "Tl", 204.38, 1, "metal");
static Element Pb = new Element(6,14,82, "Lead", "Pb", 207.2, 1, "metal");
static Element Bi = new Element(6,15,83, "Bismuth", "Bi", 208.98, 1, "metal");
// most elements after this point have unconfirmed mass do to instable isotopes
// doesn’t include uranium, does include Technetium, Thorium, Protactinium and Promethium
static Element Po = new Element(6,16,84, "Polonium", "Po", 209, 1, "metalloid");
static Element At = new Element(6,17,85, "Astatine", "At", 210, 1, "nonmetal");
static Element Rn = new Element(6,18,86, "Radon", "Rn", 222, 1, "nonmetal");
// Period 7
static Element Fr = new Element(7,1,87, "Francium", "Fr", 223, 1, "metal");
static Element Ra = new Element(7,2,88, "Radium", "Ra", 226, 1, "metal");
// Beginning of Actinoids
static Element Ac = new Element(9,1,89, "Actinium", "Ac", 227, 1, "metal");
static Element Th = new Element(9,2,90, "Thorium", "Th", 232.03,1, "metal");
static Element Pa = new Element(9,3,91, "Protactinium", "Pa", 231.03, 1, "metal");
static Element U = new Element(9,4,92, "Uranium", "U", 238.02, 1, "metal");
static Element Np = new Element(9,5,93, "Neptunium", "Np", 237, 1, "metal");
static Element Pu = new Element(9,6,94, "Plutonium", "Pu", 244, 1, "metal");
static Element Am = new Element(9,7,95, "Americium", "Am", 243, 1, "metal");
static Element Cm = new Element(9,8,96, "Curium", "Cm", 247, 1, "metal");
static Element Bk = new Element(9,9,97, "Berkelium", "Bk", 247, 1, "metal");
static Element Cf = new Element(9,10,98, "Californium", "Cf", 251, 1, "metal");
static Element Es = new Element(9,11,99, "Einsteinium", "Es", 252, 1, "metal");
static Element Fm = new Element(9,12,100, "Fermium", "Fm", 257, 1, "metal");
static Element Md = new Element(9,13,101, "Mendelevium", "Md", 258, 1, "metal");
static Element No = new Element(9,14,102, "Nobelium", "No", 259, 1, "metal");
static Element Lr = new Element(9,15, 103, "Lawrencium", "Lr", 262,1,"metal");
// Actinoids finished. Not going to do element with an unknown state as of 1/26/17
public static double getMass(String sym) {
if (sym.equals("H")) {
return H.mass;
}
else if(sym.equals("He")) {
return He.mass;
}
else if(sym.equals("Li")) {
return Li.mass;
}
else if(sym.equals("Be")) {
return Be.mass;
}
else if(sym.equals("B")) {
return B.mass;
}
else if(sym.equals("C")) {
return C.mass;
}
else if(sym.equals("N")) {
return N.mass;
}
else if(sym.equals("O")) {
return O.mass;
}
else if(sym.equals("F")) {
return F.mass;
}
else if(sym.equals("Ne")) {
return Ne.mass;
}
else if(sym.equals("Na")) {
return Na.mass;
}
else if(sym.equals("Mg")) {
return Mg.mass;
}
else if(sym.equals("Al")) {
return Al.mass;
}
else if(sym.equals("Si")) {
return Si.mass;
}
else if(sym.equals("P")) {
return P.mass;
}
else if(sym.equals("S")) {
return Si.mass;
}
else if(sym.equals("Cl")) {
return Cl.mass;
}
else if(sym.equals("Ar")) {
return Ar.mass;
}
else if(sym.equals("K")) {
return K.mass;
}
else if(sym.equals("Ca")) {
return Ca.mass;
}
else if(sym.equals("Sc")) {
return Sc.mass;
}
else if(sym.equals("Ti")) {
return Ti.mass;
}
else if(sym.equals("V")) {
return V.mass;
}
else if(sym.equals("Cr")) {
return Cr2.mass;
}
else if(sym.equals("Mn")) {
return Mn2.mass;
}
else if(sym.equals("Fe")) {
return Fe2.mass;
}
else if(sym.equals("Co")) {
return Co2.mass;
}
else if(sym.equals("Ni")) {
return Ni2.mass;
}
else if(sym.equals("Cu")) {
return Cu2.mass;
}
else if(sym.equals("Zn")) {
return Zn.mass;
}
else if(sym.equals("Ga")) {
return Ga.mass;
}
else if(sym.equals("Ge")) {
return Ge.mass;
}
else if(sym.equals("As")) {
return As.mass;
}
else if(sym.equals("Se")) {
return Se.mass;
}
else if(sym.equals("Br")) {
return Br.mass;
}
else if(sym.equals("Kr")) {
return Kr.mass;
}
else if(sym.equals("Rb")) {
return Rb.mass;
}
else if(sym.equals("Sr")) {
return Sr.mass;
}
else if(sym.equals("Y")) {
return Y.mass;
}
else if(sym.equals("Zr")) {
return Zr.mass;
}
else if(sym.equals("Nb")) {
return Nb.mass;
}
else if(sym.equals("Mo")) {
return Mo.mass;
}
else if(sym.equals("Tc")) {
return Tc.mass;
}
else if(sym.equals("Ru")) {
return Ru.mass;
}
else if(sym.equals("Rh")) {
return Rh.mass;
}
else if(sym.equals("Pd")) {
return Pd.mass;
}
else if(sym.equals("Ag")) {
return Ag.mass;
}
else if(sym.equals("Cd")) {
return Cd.mass;
}
else if(sym.equals("In")) {
return In.mass;
}
else if(sym.equals("Sn")) {
return Sn.mass;
}
else if(sym.equals("Sb")) {
return Sb.mass;
}
else if(sym.equals("Te")) {
return Te.mass;
}
else if(sym.equals("I")) {
return I.mass;
}
else if(sym.equals("Xe")) {
return Xe.mass;
}
else if(sym.equals("Cs")) {
return Cs.mass;
}
else if(sym.equals("Ba")) {
return Ba.mass;
}
else if(sym.equals("La")) {
return La.mass;
}
else if(sym.equals("Ce")) {
return Ce.mass;
}
else if(sym.equals("Pr")) {
return Pr.mass;
}
else if(sym.equals("Nd")) {
return Nd.mass;
}
else if(sym.equals("Pm")) {
return Pm.mass;
}
else if(sym.equals("Sm")) {
return Sm.mass;
}
else if(sym.equals("Eu")) {
return Eu.mass;
}
else if(sym.equals("Gd")) {
return Gd.mass;
}
else if(sym.equals("Tb")) {
return Tb.mass;
}
else if(sym.equals("Dy")) {
return Dy.mass;
}
else if(sym.equals("Ho")) {
return Ho.mass;
}
else if(sym.equals("Er")) {
return Er.mass;
}
else if(sym.equals("Tm")) {
return Tm.mass;
}
else if(sym.equals("Yb")) {
return Yb.mass;
}
else if(sym.equals("Lu")) {
return Si.mass;
}
else if(sym.equals("Hf")) {
return Hf.mass;
}
else if(sym.equals("Ta")) {
return Ta.mass;
}
else if(sym.equals("W")) {
return W.mass;
}
else if(sym.equals("Re")) {
return Re.mass;
}
else if(sym.equals("Os")) {
return Os.mass;
}
else if(sym.equals("Ir")) {
return Ir.mass;
}
else if(sym.equals("Pt")) {
return Pt.mass;
}
else if(sym.equals("Au")) {
return Au.mass;
}
else if(sym.equals("Hg")) {
return Hg.mass;
}
else if(sym.equals("Tl")) {
return Tl.mass;
}
else if(sym.equals("Pb")) {
return Pb.mass;
}
else if(sym.equals("Bi")) {
return Bi.mass;
}
else if(sym.equals("Po")) {
return Po.mass;
}
else if(sym.equals("At")) {
return At.mass;
}
else if(sym.equals("Rn")) {
return Rn.mass;
}
else if(sym.equals("Fr")) {
return Fr.mass;
}
else if(sym.equals("Ra")) {
return Ra.mass;
}
else if(sym.equals("Ac")) {
return Ac.mass;
}
else if(sym.equals("Th")) {
return Th.mass;
}
else if(sym.equals("Pa")) {
return Pa.mass;
}
else if(sym.equals("U")) {
return U.mass;
}
else if(sym.equals("Np")) {
return Np.mass;
}
else if(sym.equals("Pu")) {
return Pu.mass;
}
else if(sym.equals("Am")) {
return Am.mass;
}
else if(sym.equals("Cm")) {
return Cm.mass;
}
else if(sym.equals("Bk")) {
return Bk.mass;
}
else if(sym.equals("Cf")) {
return Cf.mass;
}
else if(sym.equals("Es")) {
return Es.mass;
}
else if(sym.equals("Fm")) {
return Fm.mass;
}
else if(sym.equals("Md")) {
return Md.mass;
}
else if(sym.equals("No")) {
return No.mass;
}
else if(sym.equals("Lr")) {
return Lr.mass;
}
return 50000;
}
public static String[] readChemForm(String chemForm) {
int lC = 0;
int arrCou = 0;
String[] elements = new String[10000];
while(lC < chemForm.length()) {
int elemCoun = 0;
int jut = chemForm.length()-lC;
if (jut > 3) {
jut = 3;
}
else{}
Boolean lengthCheck3 = true;
Boolean lengthCheck2 = true;
Boolean lengthCheck1 = true;
if (jut == 2) {
lengthCheck3 = false; }
else if(jut == 1) {
lengthCheck2 = false;
lengthCheck3 = true;
}
else if(jut <= 0) {
break;
}
else {}
String massCompF = chemForm.substring(lC,(lC+jut));
System.out.println(jut);
if ((massCompF.substring((lC+1),(lC+2)).toLowerCase().equals(massCompF.substring((lC+1),(lC+2)))) && (massCompF.length() > 2)) {
if ((massCompF.length() > 3) && (massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("2") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("3") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("4") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("5") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("6") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("7") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("8") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("9") ||massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("10") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("11") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("12") ||massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("13") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("14") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("15") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("16") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("17") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("18") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("19") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("20") || massCompF.substring((lC+2),(lC+3)).toLowerCase().equals("21"))) {
String placeHolder = massCompF.substring((lC+2),(lC+3));
if (placeHolder.equals("2")) {
elemCoun = 2;
}
else if (placeHolder.equals("3")) {
elemCoun = 3;
}
else if (placeHolder.equals("4")) {
elemCoun = 4;
}
else if (placeHolder.equals("5")) {
elemCoun = 5;
}
else if (placeHolder.equals("6")) {
elemCoun = 6;
}
else if (placeHolder.equals("7")) {
elemCoun = 7;
}
else if (placeHolder.equals("8")) {
elemCoun = 8;
}
else if (placeHolder.equals("10")) {
elemCoun = 10;
}
else if (placeHolder.equals("11")) {
elemCoun = 11;
}
else if (placeHolder.equals("12")) {
elemCoun = 12;
}
else if (placeHolder.equals("13")) {
elemCoun = 13;
}
else if (placeHolder.equals("14")) {
elemCoun = 14;
}
else if (placeHolder.equals("15")) {
elemCoun = 15;
}
else if (placeHolder.equals("15")) {
elemCoun = 15;
}
else if (placeHolder.equals("16")) {
elemCoun = 16;
}
else if (placeHolder.equals("17")) {
elemCoun = 17;
}
else if (placeHolder.equals("18")) {
elemCoun = 18;
}
else if (placeHolder.equals("19")) {
elemCoun = 19;
}
else if (placeHolder.equals("20")) {
elemCoun = 20;
}
else if (placeHolder.equals("21")) {
elemCoun = 21;
}
else{}
String sym = massCompF.substring((lC),(lC+2));
for (int i = 0; i <= elemCoun; i++) {
elements[arrCou] = sym;
}
lC += 3;
}
else{
String sym = massCompF.substring((lC),(lC+2));
elements[arrCou] = sym;
lC += 2;
}
}
else if((!(massCompF.substring((lC+1),(lC+2)).toLowerCase().equals(massCompF.substring((lC+1),(lC+2))))) && (massCompF.length() > 1)) {
if ((massCompF.length() > 2) && (massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("2") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("3") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("4") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("5") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("6") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("7") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("8") || massCompF.substring((lC+1),(lC+2)).toLowerCase().equals("9"))){
String placeHolder = massCompF.substring((lC+1),(lC+2));
if (placeHolder.equals("2")) {
elemCoun = 2;
}
else if (placeHolder.equals("3")) {
elemCoun = 3;
}
else if (placeHolder.equals("4")) {
elemCoun = 4;
}
else if (placeHolder.equals("5")) {
elemCoun = 5;
}
else if (placeHolder.equals("6")) {
elemCoun = 6;
}
else if (placeHolder.equals("7")) {
elemCoun = 7;
}
else if (placeHolder.equals("8")) {
elemCoun = 8;
}
else if (placeHolder.equals("10")) {
elemCoun = 10;
}
else if (placeHolder.equals("11")) {
elemCoun = 11;
}
else if (placeHolder.equals("12")) {
elemCoun = 12;
}
else if (placeHolder.equals("13")) {
elemCoun = 13;
}
else if (placeHolder.equals("14")) {
elemCoun = 14;
}
else if (placeHolder.equals("15")) {
elemCoun = 15;
}
else if (placeHolder.equals("15")) {
elemCoun = 15;
}
else if (placeHolder.equals("16")) {
elemCoun = 16;
}
else if (placeHolder.equals("17")) {
elemCoun = 17;
}
else if (placeHolder.equals("18")) {
elemCoun = 18;
}
else if (placeHolder.equals("19")) {
elemCoun = 19;
}
else if (placeHolder.equals("20")) {
elemCoun = 20;
}
else if (placeHolder.equals("21")) {
elemCoun = 21;
}
else{}
String sym = massCompF.substring((lC),(lC+1));
for (int i = 0; i <= elemCoun; i++) {
elements[arrCou] = sym;
}
lC += 2;
}
else{}
String sym = massCompF.substring((lC),(lC+1));
for (int i = 0; i <= elemCoun; i++) {
elements[arrCou] = sym;
}
lC++;
}
}
return elements;
}
public static void main(String[] args){
boolean quit = false;
String error = "You input something that doesn't exist. Or, I forgot an element. /n Email me at rohanrtkurup@gmail.com if you find the element you input on the periodic table and you got this error.";
while(quit == false) {
Scanner n = new Scanner(System.in);
System.out.println("Hello");
System.out.println("What program do you want to run?");
System.out.println("0: end program, 1: Gram to Gram 2:moles to moles, 3:Find mass and element composition");
int pr1 = n.nextInt();
switch(pr1) {
case 3:
System.out.println("What is the Chemical Formula");
String chemForm = n.next();
String[] elements = readChemForm(chemForm);
double totalMass = 0.0;
int lt = 0;
while (lt < elements.length) {
totalMass += getMass(elements[lt]);
lt++;
}
System.out.println("The total mass of that compound is: " + totalMass);
break;
default:
System.out.println("");
}
for(int f = 0; f <= 5; f++) {
System.out.println("");
}
}
}
}
答案 0 :(得分：0)
你有几个循环，如下所示，在循环arrCou永远不会改变，并始终为0.而sym也没有改变。似乎不对我。
for (int i = 0; i <= elemCoun; i++) {
elements[arrCou] = sym;
}
在下面的代码中，循环遍历整个元素大小而不是具有实际赋值的元素（只有第一个插槽才有任何东西）。似乎也不对。
while (lt < elements.length) {
totalMass += getMass(elements[lt]);
lt++;
}
答案 1 :(得分：0)
好的，我测试了你的代码并复制了你的问题（并发现了一些其他问题）。要修复此索引输出范围错误，您需要将以下代码作为第一个测试，如果不满足此条件，则在if语句中将其余测试短路的测试。
(massCompF.length() > #)
例如，在以下代码中，（massCompF.length（）＆gt; 2）在测试结束时。但是如果massCompF.length（）不大于2，这段代码（massCompF.substring（（lC + 1），（lC + 2））会给你索引范围错误。如果你移动（massCompF.length（ ）＆gt; 2）到开头，然后它将首先被测试，如果它不是真的，其余的测试将被跳过，所以你不会得到错误。
if ((massCompF.substring((lC+1),(lC+2)).toLowerCase().equals(massCompF.substring((lC+1),(lC+2)))) &&
(massCompF.length() > 2)) {
...
}
我发现的另一个问题（您可以通过在修复上述错误后输入H作为元素来复制它）是您的后续循环可能无穷无尽，因为在您的代码中，lC不能保证增加。
while(lC < chemForm.length()) {
...
}
当然，我可以看到您的代码尚未完成。在这里，我只是指出了我发现的事情。