Check out example codes for "sql developer sql worksheet not showing". It will help you in understanding the concepts better.
Code Example 1
I was able to solve this by : Closing SQL developer Deleting the file SqlHistory.xml that is located at C:\Users\AppData\Roaming\SQL Developer\. Alternatively, you can rename it to e.g SqlHistoryOLD.xml Now when you open SQL developer and create a new SQL worksheet, it will work :)
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