I have this in my jsp page : ${category.name_ENG} which has \"Car\" as value
but i have the local language in an another varialbes : ${locale}
Use JSTL to concatenate a string in EL and then use brace notation [] to access properties with a dynamic key.
${category[name]}
By the way, if the sole functional requirement is internationalization/localization, then there are way much better ways than fiddling like this: How to internationalize a Java web application?