如何将 NFA/DFA 转换为 Java？
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How to convert NFA/DFA to java?
提问by Inco Mob
I have a scenario where I have designed the NFA and using JFLAP I have converted it to DFA.
我有一个场景，我设计了 NFA 并使用 JFLAP 将其转换为 DFA。
I need to know, how to code it in Java?
我需要知道，如何用 Java 编码？
Basically how to implement those state transitions in Java. I have seen some examples which do this using switch and if statements, but I can't see any relation to DFA/NFA design and how to use it to implement in Java.
基本上如何在 Java 中实现这些状态转换。我已经看到一些使用 switch 和 if 语句执行此操作的示例，但是我看不到与 DFA/NFA 设计以及如何使用它在 Java 中实现的任何关系。
回答by ratchet freak
if you want to use a more object oriented design over while(true)switch(state){...}
如果你想使用更面向对象的设计而不是 while(true)switch(state){...}
public class State{
private Map<Character,State> transitions=new HashMap<Character,State>();
public void addTransition(char ch,State st){
transitions.put(ch,st);
}
public State next(char ch){
return transitions.get(ch);
}
private boolean fin=false;
public boolean isFinal(){return fin;}
public boolean setFinal(boolean f){fin=f;}
}
and then the loop will be
然后循环将是
State currState=startState;
while(currState!=null && input.hasNextChar()){//you can also end directly when final state is reached
char next = input.nextChar();//get next character
currState = currState.next(next);
}
if(currState!=null && currState.isFinal()){
// reached final state
}else{
// to bad didn't match
}
回答by NPE
Take a look at dk.brics.automaton:
This Java package contains a DFA/NFA (finite-state automata) implementation with Unicode alphabet (UTF16) and support for the standard regular expression operations (concatenation, union, Kleene star) and a number of non-standard ones (intersection, complement, etc.)
这个 Java 包包含一个带有 Unicode 字母表 (UTF16) 的 DFA/NFA（有限状态自动机）实现，并支持标准正则表达式操作（连接、联合、Kleene 星）和许多非标准操作（交、补、等等。）
回答by RSS
Although you would have implemented it by now but there is very good implementation which is easy to digest. Use Digraph to maintain the epsilon transitions and stack to keep track of expressions. Check out this link from RS NFA.java .
虽然您现在已经实现了它，但有一个很好的实现，很容易理解。使用 Digraph 维护 epsilon 转换和堆栈以跟踪表达式。从 RS NFA.java查看此链接。
