Error while parsing for-loop using javaparse

Question

It's continuous of my previous question: How to parse a for-loop using Javaparser? . I'm trying to parse this incorrect for-loop: FOR(j, k, 15, >, -); to the correct form: for (var j = k; j > 15; j--){} . It means to parse Class.java to the class ClassAltered.java. My code should create the new class ClassAltered.java with the correct loop-for. Now my method to parse the for-loop is commented (I haven't finished it), but anyway I have the same error. I'm sure that javaparser could parse incorrect statements, but I have problems with the sights ">", "<=", "+", "-". If I delete this sights everything works. I use javaparser-core-3.1.0.jar

Here is my error:

Here is my Class.java which I want to parse:

public class Class {
public static void main(String[] args) {
    method1();
    method2();
}

public static void method1() {
FOR(j, k, 15, >, -);
System.out.println("FOR(j, k, 15, >, -) test");
}

public static void method2() {
FOR(j, 0, 10, <=, +);
System.out.println("FOR(j, 0, 10, <=, +) test");
}
}

Here is my Main.class:

 import com.github.javaparser.JavaParser;
 import com.github.javaparser.ast.CompilationUnit;
 import com.github.javaparser.ast.expr.*;
 import com.github.javaparser.ast.stmt.ForStmt;

 import javax.tools.*;

 import java.io.*;
 import java.util.*;

 public class Main {

 public static void main(String[] args) throws IOException {
    final String fileName = "Class.java";
    final String alteredFileName = "src\\ClassAltered.java";
    CompilationUnit cu;
    try(FileInputStream in = new FileInputStream(fileName)){
        cu = JavaParser.parse(in);
    }

    //cu.getChildNodesByType(ForStmt.class)
    //.forEach(Main::setForStatement);

    cu.getClassByName("Class").get().setName("ClassAltered");

    try(FileWriter output = new FileWriter(new File(alteredFileName), false)) {
        output.write(cu.toString());
    }

    File[] files = {new File(alteredFileName)};
    String[] options = { "-d", "out//production//Synthesis" };

    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
    try (StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null)) {
        Iterable<? extends JavaFileObject> compilationUnits =
            fileManager.getJavaFileObjectsFromFiles(Arrays.asList(files));
        compiler.getTask(
            null,
            fileManager,
            diagnostics,
            Arrays.asList(options),
            null,
            compilationUnits).call();

        diagnostics.getDiagnostics().forEach(d ->    System.out.println(d.getMessage(null)));
    }
}

 /*private static void setForStatement(ForStmt forStmt) {

    MethodCallExpr initializer = (MethodCallExpr) forStmt.getInitialization().get(0);

    if (initializer.getArguments().size() == 5
            && initializer.getArgument(1) instanceof IntegerLiteralExpr
            && initializer.getArgument(2) instanceof IntegerLiteralExpr) {
        IntegerLiteralExpr a1 = (IntegerLiteralExpr) initializer.getArgument(1);
        IntegerLiteralExpr a2 = (IntegerLiteralExpr) initializer.getArgument(2);
    }
}*/
}

Answer 1

I do not think you should relay on the way JavaParser deal with incorrect statements. Parsing incorrect statements is something complicate and brittle. There is no "right" way to parse something that is not Java in a Java file.

I would wonder how that code ended up in a JavaParser file: was it generated by some faulty code generator? Any chance you can fix that generator instead of reverse engineering an incorrect file?

Disclaimer: I am a JavaParser contributor