在編寫語法分析程序時，求解非終結(jié)符的FIRST和FOLLOW集合是非常重要的。JAVA語言通過使用算法可以很方便地自動化地實現(xiàn)這個過程。

public void computeFirst(){
for (NonTerminal nt : nonTerminals) {
computeFirst(nt);
}
}
private void computeFirst(NonTerminal nt){
if (nt.firstComputed) {
return;
}
nt.firstComputed = true;
for (ProductionRule r : nt.productionRules) {
List<Symbol> symbols = r.symbols;
if (symbols.isEmpty()) {
nt.first.add(Token.EPSILON);
continue;
}
int k = 0;
while (k < symbols.size()) {
Symbol s = symbols.get(k);
if (s instanceof Terminal) {
nt.first.add(s);
break;
} else if (s instanceof NonTerminal) {
NonTerminal nt2 = (NonTerminal) s;
computeFirst(nt2);
nt.first.addAll(nt2.first);
if (!nt2.first.contains(Token.EPSILON)) {
break;
}
k++;
}
}
if (k == symbols.size()) {
nt.first.add(Token.EPSILON);
}
}
}
public void computeFollow(){
startSymbol.follow.add(Token.EOF);
for (NonTerminal nt : nonTerminals) {
computeFollow(nt);
}
}
private void computeFollow(NonTerminal nt){
if (nt.followComputed) {
return;
}
nt.followComputed = true;
for (ProductionRule r : nt.productionsUsingThisNonTerminal) {
int i = r.symbols.indexOf(nt);
if (i == r.symbols.size() - 1) {
if (!nt.equals(r.leftHandSide)) {
computeFollow(r.leftHandSide);
nt.follow.addAll(r.leftHandSide.follow);
}
} else {
Symbol next = r.symbols.get(i + 1);
if (next instanceof Terminal) {
nt.follow.add(next);
} else {
NonTerminal nt2 = (NonTerminal) next;
computeFirst(nt2);
nt.follow.addAll(nt2.first);
if (nt2.first.contains(Token.EPSILON)) {
computeFollow(nt2);
nt.follow.addAll(nt2.follow);
}
}
}
}
}

以上代碼演示了如何求解非終結(jié)符的FIRST和FOLLOW集合，具體內(nèi)容可以參考上述代碼。