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public static int readConvert(char[]post)throws IOException{
Stack S = new Stack();
int j=0;
char c;
System.out.printf("Type an infix expression and press Enter\n");
char token =getToken();
while (token!='\0'){
if (Character.isDigit(token))post [j++]=token;
else if (token =='(')S.push(new NodeData('('));
else if (token ==')')
while ((c=S.pop().getData())!='(')post[j++]=c;
else {
while (!S.empty() && precedence(S.peek().getData())>= precedence(token))
post[j++]=S.pop().getData();
S.push(new NodeData(token));
}
token=getToken();
}
while (!S.empty())post[j++]=S.pop().getData();
return j;
}
问题：（1）那为什么日食是告诉我，我的getData（）是未定义的类型对象。未定义的类型对象缀与postfix
类我创建：
public class Node{
public NodeData data;
NodeData next;
public Node(Nodedata d){
data = d;
next = null;
}
public class NodeData{
char ch;
public NodeData(char c){
ch =c;
}
public char getData() {return ch;}
public int compareTo(NodeData nd){
if (this.ch ==nd.ch)return 0;
if (this.ch<nd.ch) return -1;
return 1;
}
public String toString(){
return ch + " "; //" " needed to convert num to a string
}
}
}
问题：（2）为什么，当我尝试编译日食表明NODEDATA不能成为解决的类型。