Tag Archives: cannot find symbol error

[Javac compilation exception] javac compilation prompts that the package in jdk cannot be found error: package jdk.internal.org.objectweb.asm does not exist and error: cannot find symbol

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1. Steps to reproduce

1) Write the java class to be compiled

package f_asm_and_javassist;

import jdk. internal .org.objectweb.asm.* ;

import java.io. * ;

import static jdk. internal .org.objectweb.asm.Opcodes.ASM5;

/* *
 * @Author zhangboqing
 * @Date 2020/3/26
 */ 
public  class AsmDemo {

    // Methods and fields to access the class 
    public  static  void main(String[] args) {
         byte [] bytes = getBytes(); // Byte array of the MyMain.class file 
        ClassReader cr = new ClassReader(bytes);
        ClassWriter cw = new ClassWriter( 0 );
        ClassVisitor cv = new ClassVisitor(ASM5, cw) {
            @Override
            public FieldVisitor visitField( int access, String name, String desc, String signature, Object value) {
                System. out .println( " field: " + name);
                 return super.visitField(access, name, desc, signature, value);
            }

            @Override
            public MethodVisitor visitMethod( int access, String name, String desc, String signature, String[] exceptions) {
                System. out .println( " method: " + name);
                 return super.visitMethod(access, name, desc, signature, exceptions);
            }
        };
        cr.accept(cv, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG);
    }

    private  static  byte [] getBytes() {

        StringBuilder sb = new StringBuilder();
         try (FileInputStream fileInputStream = new FileInputStream( new File( " MyMain.class " ));
            BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream)) {

            byte [] buffer = new  byte [ 1024 * 8 ];
             while (bufferedInputStream.available()> 0 ) {

                int length = bufferedInputStream.read(buffer);
                sb.append( new String(buffer, 0 ,length) );
            }


        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return sb.toString().getBytes();
    }
}

2) Use javac to compile in the current directory

 javac -d. AsmDemo.java

Prompt the following error:

➜ f_asm_and_javassist git:(master) ✗ javac- d. AsmDemo.java
AsmDemo.java: 3 : error: package jdk. internal .org.objectweb.asm does not exist
import jdk. internal .org.objectweb.asm.* ;
 ^ 
AsmDemo.java: 7 : error: package jdk. internal .org.objectweb.asm does not exist
import static jdk. internal .org.objectweb.asm.Opcodes.ASM5;
                                             ^ 
AsmDemo.java: 7 : error: static import only from classes and interfaces
import static jdk. internal .org.objectweb.asm.Opcodes.ASM5;
 ^ 
AsmDemo.java: 18 : error: cannot find symbol
        ClassReader cr = new ClassReader(bytes);
         ^ 
  symbol:    class ClassReader
  location: class AsmDemo
AsmDemo.java: 18 : error: cannot find symbol
        ClassReader cr = new ClassReader(bytes);
                              ^ 
  symbol:    class ClassReader
  location: class AsmDemo
AsmDemo.java: 19 : error: cannot find symbol
        ClassWriter cw = new ClassWriter( 0 );
         ^ 
  symbol:    class ClassWriter
  location: class AsmDemo
AsmDemo.java: 19 : error: cannot find symbol
        ClassWriter cw = new ClassWriter( 0 );
                              ^ 
  symbol:    class ClassWriter
  location: class AsmDemo
AsmDemo.java: 20 : error: cannot find symbol
        ClassVisitor cv = new ClassVisitor(ASM5, cw) {
         ^ 
  symbol:    class ClassVisitor
  location: class AsmDemo
AsmDemo.java: 20 : error: cannot find symbol
        ClassVisitor cv = new ClassVisitor(ASM5, cw) {
                               ^ 
  symbol:    class ClassVisitor
  location: class AsmDemo
AsmDemo.java: 20 : error: cannot find symbol
        ClassVisitor cv = new ClassVisitor(ASM5, cw) {
                                            ^
  symbol: variable ASM5
  location: class AsmDemo
AsmDemo.java: 33 : error: cannot find symbol
        cr.accept(cv, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG);
                       ^
  symbol: variable ClassReader
  location: class AsmDemo
AsmDemo.java: 33 : error: cannot find symbol
        cr.accept(cv, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG);
                                               ^
  symbol: variable ClassReader
  location: class AsmDemo
 12 errors

 

2. the solution

This is the limitation of javac. By default, javac will not read classes from rt.jar. It is read from a symbol file that contains only standard APIs and some internal APIs (such as com.sun., com.oracle. and sun. *).

To disable this mechanism, you can use javac -XDignore.symbol.file=true 

With maven, you can use:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <configuration>
    <compilerArgument>-XDignore.symbol.file</compilerArgument>
  </configuration>
</plugin>

The above problem can be successfully executed with the following command:

javac -XDignore.symbol.file=true -d. AsmDemo.java

For the class to be package name, you need to use -d., which means that the package path is automatically generated in the current directory