Set the value of a final field in debug mode in IntelliJ IDEA

user_4759182 0
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I'm debugging a method in IntelliJ IDEA and in debug mode I need to set the value of a final field. Is possible to achieve in some way?

This is the image of my IDE in debug mode, I'm trying to change the value of the collectionId variable.

IDE

intellij-idea debugging java
2 Answers

IntelliJ IDEA (and Java debugger API) doesn't support it. Comment from the responsible developer:

There's a check in Java JDI code (com.sun.tools.jdi.ObjectReferenceImpl#setValue) that does not allow to change value of a final field, it was added long ago.

ObjectReferenceImpl.java#L236:

        // Make sure the field is valid
        ((ReferenceTypeImpl)referenceType()).validateFieldSet(field);

ReferenceTypeImpl.java#L614:

    void validateFieldSet(Field field) {
        validateFieldAccess(field);
        if (field.isFinal()) {
            throw new IllegalArgumentException("Cannot set value of final field");
        }
    }

The reason why it's not allowed is that changing final fields may lead to inconsistency in behavior: some values may be "inlined" by the compiler already and will not be changed.

user_1048910

Well, it is doable. Adapt & type the below in the evaluate/modify Intellij dialog:

Field finalF = this.getClass().getDeclaredField( "m_field" );
finalF.setAccessible(true);
finalF.setInt(this, newValue);
user_23782520
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