java - 如何从 "int a, b, c = 0, d;"中提取子字符串(变量名称)

Question

我的代码可以在文本文件中搜索字符串“int”并从中搜索子字符串(变量名称)，但我对子字符串(变量名称)有一些问题

like "int a, b, c = 0, d;"

我希望我的输出是:

• 变量名称是:a
• 变量名称为:b
• 变量名称为:c
• 变量名称为:d

我可以修改我的代码吗？

这是我的代码。

                //print variable name and position
                int k4 = line.indexOf("=",k+1);
                int k5 = line.indexOf(";", k+1);
                int k6 = line.indexOf(",", k+1);
                int cTemp1 = 0;

                //Count whitespace before variable name, print variable name and length of variable name
                if (k4 != -1){
                    String temp4 = line.substring(k+3, k4);     //Substring variable name
                    if(k4 != -1){
                        int varName = line.indexOf(temp4.trim(), k+3);
                        String total_length = line.substring(k+3, varName);     
                        int wPattern = total_length.length();       
                        System.out.println("  - Whitespace before variable name \"" + temp4.trim() + "\" are: ," + wPattern);
                    }
                    System.out.println("  - Variable name type INTEGER at line: " + lineNumber + " is: "+temp4.trim());
                    System.out.print("  - Length of variable name \"" + temp4.trim() + "\" is: ," + temp4.trim().length() + "\n\n");
                    varLength_Integer1 += temp4.trim().length();
                }
                else if(k5 != -1){
                    String temp5 = line.substring(k+4, k5);
                    System.out.println("  - Variable name type INTEGER at line: " + lineNumber + " is: "+temp5.trim());
                    System.out.print("  - Length of variable name \"" + temp5.trim() + "\" is: ," + temp5.trim().length() + "\n\n");
                    varLength_Integer2 += temp5.trim().length();
                }
                else if(k6 != -1){
                    String temp6 = line.substring(k+4, k6);
                    System.out.println("  - Variable name type INTEGER at line: " + lineNumber + " is: "+temp6.trim());
                    System.out.print("  - Length of variable name \"" + temp6.trim() + "\" is: ," + temp6.trim().length() + "\n\n");
                    varLength_Integer3 += temp6.trim().length();
                }
                avgInteger += (varLength_Integer1 + varLength_Integer2 + varLength_Integer3)/(double)c3;
                //END Count whitespace before variable name, print variable name and length of variable name

            }

非常感谢。

Answer 1

我想用正则表达式来做到这一点

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class ParseInt {

    public static void main(String[] args) {
        String test =  "int a, b, c = 0, d;\n\nint e, b, c = 0, d";

        String pattern = "int(.*)";
        Pattern r = Pattern.compile(pattern);

        String patternVar = "([A-Za-z][a-zA-Z_0-9]*)(\\[\\])?";
        Pattern rVar = Pattern.compile(patternVar);

        String[] linesNewline = test.split("\n");

        for (int nLI=0;nLI < linesNewline.length; ++nLI) {
            String[] lines = linesNewline[nLI].split(";");
            for (int i=0;i < lines.length; ++i) {
                Matcher m = r.matcher(lines[i]);
                if (m.find()) {
                    String[] variables = m.group(1).split(",");
                    for (int ii=0; ii < variables.length; ++ii) {
                        Matcher mVar = rVar.matcher(variables[ii].trim());
                        if (mVar.find()) {
                            System.out.println("Variable is " + mVar.group(1));
                    }
                }
            }
        }
    }
  }
}

输出针对输入字符串“int a, b, c = 0, d;\n\nint e, b, c = 0, d”

Variable is a
Variable is b
Variable is c
Variable is d
Variable is e
Variable is b
Variable is c
Variable is d

输出针对输入字符串“int a, a1, b, b1;”

Variable is a
Variable is a1
Variable is b
Variable is b1

输出针对输入字符串“int d[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };”

Variable is d

输出针对输入字符串“int d0 = sc.nextInt(); int d1 = sc.nextInt(); int d2 = sc.nextInt();”

Variable is d0
Variable is d1
Variable is d2