Getting the java.lang.ClassCastException: java.lang.String cannot be cast to java.sql.Clob

Question

Getting the java.lang.ClassCastException: java.lang.String cannot be cast to java.sql.Clob Error when trying to convert String into Clob type . we are using Mysql database .java side we are using Hibernate NativeQuery .

Query nativeQuery= entityManager.createNativeQuery(QueryConstants.GetDbDetails);
        
        nativeQuery.unwrap(SQLQuery.class)
        .setParameterList("crisilTicker", crisilTickerList);
        
        
        List<Object[]> list=nativeQuery.getResultList();
        try{
            if(list !=null && !list.isEmpty()){
                for(Object[] obj :list){
                    java.sql.Clob clobevalue =(java.sql.Clob) obj[0];
                    String metaDataStr =clobevalue.getSubString(1, (int) clobevalue.length());
                    JSONObject metaDataJson =new JSONObject(metaDataStr);
                    JSONObject metaData = metaDataJson.getJSONObject("sheetMetadata");
                    Iterator<String> keys = metaData.keys();
                    while (keys.hasNext()) {

getting java.lang.ClassCastException: java.lang.String cannot be cast to java.sql.Clob error

Does this answer your question? [how to Retrive the CLOB value from Oracle using java](https://stackoverflow.com/questions/19486648/how-to-retrive-the-clob-value-from-oracle-using-java) — Nowhere Man, Oct 07 '20 at 07:02
You cannot cast a String to a Clob. That is not how Java works. — Mark Rotteveel, Oct 07 '20 at 20:03

score 0 · Answer 1 · answered Oct 07 '20 at 06:49

0

Have you tried to cast to String instead of Clob type?

String metaDataStr = (String) obj[0];

And remove this line in your code

java.sql.Clob clobevalue =(java.sql.Clob) obj[0];

answered Oct 07 '20 at 06:49

Hưng Chu

1,027
5
11

I need Clob instead of String – Dorayya Oct 07 '20 at 06:54

Gaurav Dhiman · Answer 2 · 2020-10-07T06:56:47.960

0

If you want to cast String to Clob, use below :-

 java.sql.Clob clobevalue = new new javax.sql.rowset.serial.SerialClob(((String)obj[0]).toCharArray());

edited Oct 07 '20 at 06:56

answered Oct 07 '20 at 06:51

Gaurav Dhiman

953
6
11

obj[0].toCharArray() here toCharArray() getting error because of obj[0] doesn't have toCharArray() – Dorayya Oct 07 '20 at 06:54
Cast obj[0] to String. Edit made to the answer. – Gaurav Dhiman Oct 07 '20 at 06:57

Getting the java.lang.ClassCastException: java.lang.String cannot be cast to java.sql.Clob

2 Answers2