【发布时间】：2021-04-08 11:01:13
【问题描述】：
我正在用 Java 设计一个编译器。在此，我从文本文件中读取输入，并在有条件的情况下将该输入存储到符号表中。现在我想检查重复项，然后不想将重复项数据添加到表中。
我使用了 Set，我知道它不允许重复，并且程序没有将重复的数据添加到表中，但它也在打印 Data Inserted，而我没有。我想当文本中存在重复数据时，程序应该说数据已经存在。
以下是将数据添加到表中的代码。
case 10:
if(str.contains("=")){
System.out.println("Token name = otop");
System.out.println("Attribute value = ASN");
if(str.startsWith("=")){
break;
}
else{
try{
String a[] = str.split(" ");
type = a[0];
lexeme = a[1];
value = a[3];
if(value.endsWith(";")){
value = value.replace(";", "");
if(type.contains("int") && value.matches("[-+][0-9]*")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("float") && value.matches("[0-9].[0-9]*")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("string") && value.matches("\"[A-Z a-z 0-9]*\"")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("char") && value.matches("\'[A-Za-z0-9]\'")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else{
System.out.println("ERROR: Type MissMatch!");
}
}
else if(!value.endsWith(";")){
System.out.println("\nERROR: ; expected on line number " +lineNumber.getLineNumber() + " in the text file");
}
}
catch(Exception e){
System.out.println("Error: Try to declare variale with spaces e.g int a = 5;");
}
}
break;
}
我得到的输出是：
f
l
o
a
t
a
=
5
.
5
;
Token name = otop
Attribute value = ASN
Data Inserted in the table!
f
l
o
a
t
a
=
5
.
5
;
Token name = otop
Attribute value = ASN
Data Inserted in the table!
----------------------------------------------------------------------------------
--Symbol Table--
Lexeme Token name Type Attribute value
a id float 5.5
----------------------------------------------------------------------------------
我该如何解决这个问题？作为参考，我附上下面的整个代码：
import java.io.FileReader;
import java.util.*;
import java.io.LineNumberReader;
import java.io.FileNotFoundException;
import java.io.IOException;
public class main {
public static void main(String[] args) throws FileNotFoundException, IOException{
LineNumberReader lineNumber;
FileReader newFile = new FileReader( "C:/temp/sourcecode.txt");
lineNumber = new LineNumberReader(new FileReader("C:/temp/sourcecode.txt"));
Scanner scanFile = new Scanner(newFile);
//Scanner scan = new Scanner(System.in);
//char s;
String str, lexeme, type, value;
//String str1 = "\"[A-Za-z]*\"";
Set<String> tabledata = new HashSet<>();
while(scanFile.hasNextLine() && lineNumber.readLine() != null){
str = scanFile.nextLine();
//lexeme.add(str);
if(!str.startsWith("//") && !str.startsWith("/*") && !str.endsWith("*/")) {
for(int i =0; i<=str.length()-1 ; i++) {
str = str.replace("\\s", "");
str = str.replaceAll("\t", "");
str = str.replaceAll("\n", "");
System.out.println(str.charAt(i));
}
int OP = 0;
switch(OP){
case 0:
if(str.contains("<") && str.contains(">")){
System.out.println("Token name : relop");
System.out.println("Attribute value = NE");
break;
}
case 1:
if(str.contains("<") && str.contains("=")){
System.out.println("Token name = relop");
System.out.println("Attribute value = LE");
break;
}
case 2:
if(str.contains(">") && str.contains("=")){
System.out.println("Token name = relop");
System.out.println("Attribute value = GE");
break;
}
case 3:
if(str.contains("<")){
System.out.println("Token name = relop");
System.out.println("Attribute value = LT");
break;
}
case 4:
if(str.contains(">")){
System.out.println("Token name = relop");
System.out.println("Attribute value = GT");
break;
}
case 5:
if(str.contains("==")){
System.out.println("Token name = relop");
System.out.println("Attribute value = EQ");
break;
}
case 6:
if(str.contains("+")){
System.out.println("Token name = arop");
System.out.println("Attribute value = ADD");
break;
}
case 7:
if(str.contains("-")){
System.out.println("Token name = arop");
System.out.println("Attribute value = SUB");
break;
}
case 8:
if(str.contains("*")){
System.out.println("Token name = arop");
System.out.println("Attribute value = MUL");
break;
}
case 9:
if(str.contains("/")){
System.out.println("Token name = arop");
System.out.println("Attribute value = DIV");
break;
}
case 10:
if(str.contains("=")){
System.out.println("Token name = otop");
System.out.println("Attribute value = ASN");
if(str.startsWith("=")){
break;
}
else{
try{
String a[] = str.split(" ");
type = a[0];
lexeme = a[1];
value = a[3];
if(value.endsWith(";")){
value = value.replace(";", "");
if(type.contains("int") && value.matches("[-+][0-9]*")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("float") && value.matches("[0-9].[0-9]*")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("string") && value.matches("\"[A-Z a-z 0-9]*\"")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else if(type.contains("char") && value.matches("\'[A-Za-z0-9]\'")){
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\t"+value);
System.out.println("Data Inserted in the table!");
}
else{
System.out.println("ERROR: Type MissMatch!");
}
}
else if(!value.endsWith(";")){
System.out.println("\nERROR: ; expected on line number " +lineNumber.getLineNumber() + " in the text file");
}
}
catch(Exception e){
System.out.println("Error: Try to declare variale with spaces e.g int a = 5;");
}
}
break;
}
// case 11:
// if(str.contains("'")){
// System.out.println("Token name = otop");
// System.out.println("Attribute value = PRN");
// break;
// }
case 12:
if(str.contains(";")){
System.out.println("Token name = otop");
System.out.println("Attribute value = LNTR");
if(str.startsWith(";")){
break;
}
String p[] = str.split(" ");
type = p[0];
lexeme = p[1];
if(lexeme.endsWith(";")){
System.out.println(p[1]);
lexeme = lexeme.replace(";", "");
tabledata.add(lexeme+"\t\tid\t\t"+type+"\t\tNull");
System.out.println("Data Inserted in the table!");
}
else if(!lexeme.endsWith(";")){
System.out.println("\nERROR: ; expected on line number " +lineNumber.getLineNumber() + " in the text file");
}
break;
}
case 13:
if(str.contains("{")){
System.out.println("Token name = otop");
System.out.println("Attribute value = LBRC");
break;
}
case 14:
if(str.contains("}")){
System.out.println("Token name = otop");
System.out.println("Attribue value = RBRC");
break;
}
case 15:
if(str.contains("begin")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 1");
break;
}
case 16:
if(str.contains("end")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 2");
break;
}
case 17:
if(str.contains("if")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 3");
break;
}
case 18:
if(str.contains("then")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 4");
break;
}
case 19:
if(str.contains("else")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 5");
break;
}
case 20:
if(str.contains("int")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 6");
break;
}
case 21:
if(str.contains("float")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 7");
break;
}
case 22:
if(str.contains("char")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 8");
break;
}
case 23:
if(str.contains("string")){
System.out.println("Token name = Keyword");
System.out.println("Attribute value = 9");
break;
}
case 24:
if(str.matches("[A-Za-z_][A-Za-z_0-9_]*")){
System.out.println("Token name = id");
tabledata.add(str+"\t\tid\t\tIdentifier\tNull");
System.out.println("Data Inserted in the table!");
break;
}
case 25:
if(str.matches("[+0-9]*")){
System.out.println("Token name = uint");
tabledata.add("Null\t\tuint\t\tint\t\t"+str);
System.out.println("Data Inserted in the table!");
break;
}
case 26:
if(str.matches("\"[A-Z a-z]*\"")) {
System.out.println("Token name = sliteral");
tabledata.add("Null\t\tsliteral\tstring\t\t"+str);
System.out.println("Data Inserted in the table!");
break;
}
case 27:
if(str.matches("[0-9].[0-9]*")){
System.out.println("Token name = float const");
tabledata.add("Null\t\tfloat const\tfloat\t\t"+str);
System.out.println("Data Inserted in the table!");
break;
}
case 28:
if(!str.contains("<>|>=|<=|<|>|==|+|-|/|*|'|;|{|}|=|begin|end|else|if|then|int|float|char|string") && !str.matches("\"[A-Z a-z]*\"") && !str.matches("\'[A-Za-z]\'")){
System.out.println("The unrecognized lexeme is :" +str);
System.out.println("Line Number :" + lineNumber.getLineNumber());
System.out.println("Error: unrecognized token found!");
}
case 29:
if(str.matches("\'[A-Za-z]\'")){
System.out.println("Token name = char const");
tabledata.add("Null\t\tchar const\tchar\t\t"+str);
System.out.println("Data Inserted in the table!");
break;
}
}
}
}
}
【问题讨论】：
标签： java duplicates set