What is type class [S

Question

I have a SQL database in a Gridgain cache and one column of that database is a short array.

Column name	Data type
Order Id	Integer
Timestamp	Long
Activity	Short []

My SQL query is like this. String sql = "Select activity from cache where orderId = ? and timestamp <= ? and timestamp >= ? "; I am executing following java code. Since I am not sure about the return data type I assigned the return value to an object and printed its type. result was

XX [S@3eb7630d XX type class [S

Code is

Object xx = null;
List<Short> activityList = new ArrayList<>();
try (QueryCursor<List<?>> cursor = patientTriggerCache.query(sql)) {
                    for (List<?> row : cursor) {
                        xx = row.get(0);
                        activityList.add((short) xx);
                    }
                }

error is

java.lang.ClassCastException: [S cannot be cast to java.lang.Short

Yes, it's `short[]` - see https://docs.oracle.com/javase/10/docs/api/java/lang/Class.html#getName() — Jon Skeet, Sep 10 '21 at 06:29
This related question provides some background: https://stackoverflow.com/questions/5085889/l-array-notation-where-does-it-come-from — Hulk, Sep 10 '21 at 07:17

Audrius Meškauskas · Answer 1 · 2021-09-10T06:41:03.697

3

[S is the runtime signature of an array of integers of type short (the primitive type, not java.lang.Short). The run time signature of an array of integers of type int would be [I.

    short x[] = new short[10];
    System.out.println("Hello "+x);

The output is Hello [S@6d06d69c.

As correctly noted by @Jon Skeet in comment, these names can be found here.

edited Sep 10 '21 at 06:41

answered Sep 10 '21 at 06:35

Audrius Meškauskas

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But the problem is `java.lang.ClassCastException: [S cannot be cast to java.lang.Short` this error. I changed the question content for a better understanding. – sachith Sep 10 '21 at 08:57
short and java.lang.Short are completely different classes. – Audrius Meškauskas Sep 10 '21 at 09:49
any leads how to do that? – sachith Sep 10 '21 at 10:00

What is type class [S

1 Answers1