feat: Add Java equivalent of COBOL SQL example program (PostgreSQL account handler)

[devin-ai-integration]

Summary

Adds a complete Java port of the existing COBOL SQL example program (sql/sql_example.cbl) under a new sql/java/ directory. The Java version provides identical functionality — connecting to the cobol_db_example PostgreSQL database and offering an interactive console menu to display all accounts, display disabled accounts, and search accounts by name/phone/address.

New files:

• Account.java — POJO mirroring the COBOL ws-account-record structure (8 fields)
• AccountHandler.java — JDBC connection lifecycle + three query methods mirroring the COBOL cursors (ACCOUNT-ALL-CUR, ACCOUNT-DISABLED-CUR, ACCOUNT-QUERY-CUR), plus tabular display output
• Main.java — Interactive menu loop replicating the COBOL main-procedure (menu selection, search-again sub-loop, connect-on-start / disconnect-on-exit)
• sql/java/README.md — Prerequisites, compile/run instructions, connection config

Updated: sql/README.md — added cross-reference to the new Java implementation.

All queries use PreparedStatement. Error handling prints SQL state/code/message matching the COBOL check-sql-state pattern. Connection failure calls System.exit(1) mirroring the COBOL stop run.

Review & Testing Checklist for Human

• End-to-end test (most important): Stand up PostgreSQL, run create_test_db.sql, compile with the JDBC driver on classpath (javac -cp .:postgresql-*.jar *.java), then run java -cp .:postgresql-*.jar Main and exercise all 4 menu options. Verify output matches the COBOL program.
• Verify displayAccounts column widths against the COBOL display-account-results paragraph (lines 400–430 of sql_example.cbl). The printf format strings should produce aligned columns matching the COBOL fixed-width output.
• Verify SQL queries match the three COBOL cursor declarations exactly (lines 118–153 of sql_example.cbl) — same columns, same ORDER BY, same WHERE clauses.
• searchAccounts(null) produces "%null%" rather than throwing — acceptable for this demo scope, but confirm this is fine.
• README says JDK 17+ but code compiles on JDK 11 with no post-Java-8 features — decide if the prerequisite should be relaxed.

Notes

• createDt/modDt are stored as String (matching COBOL PIC X(20)) rather than java.sql.Timestamp. Intentional for COBOL parity; display format depends on the JDBC driver's default timestamp-to-string conversion.
• DB credentials are hardcoded constants matching the COBOL connection string — appropriate for this example repo.
• All classes are in the default package (no package declaration), consistent with the simple example nature of the repo.
• This PR consolidates work from three child session PRs (docs: Add Java SQL example README and update SQL README #78, feat: Add Main.java with interactive console menu for Java SQL example #79, feat: Add Account POJO and AccountHandler with JDBC connection and query methods #80) which can be closed in favor of this one.

Link to Devin session: https://app.devin.ai/sessions/2391de1faa624377bb458732ddb38350
Requested by: @Colhodm

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 3 additional findings.

[devin-ai-integration]

End-to-End Test Results

Ran the Java program locally against PostgreSQL 14 with 11-row test dataset. All menu options exercised.

All 9 tests passed

#	Test	Result
1	Startup & DB connection	PASSED
2	Display all accounts (option 1) — 11 rows, ordered by ID	PASSED
3	Display disabled accounts (option 2) — 3 rows, all Enabled=N	PASSED
4	Search "John" (option 3) — 1 exact match	PASSED
5	Search "St" — partial match, all 11 rows returned	PASSED
6	Search "ZZZZZ" — no match, zero data rows	PASSED
7	Decline search again ("N") — returns to menu	PASSED
8	Invalid menu option ("9") — error message shown	PASSED
9	Exit (option 4) — "Disconnected.", exit code 0	PASSED

Full output

COBOL SQL DB Example Program - Java Edition
--------------------------------------------
Connected to database.

1) Display all accounts
2) Display disabled accounts
3) Query accounts
4) Exit
Selection: 
ACCOUNTS:

 ID    | First    | Last     | Phone      | Address                | Enabled
------|----------|----------|------------|------------------------|---------
 1     | John     | Tester   | 15555550100 | 123 Fake St, Nowhere   | Y
 2     | Mike     | Tester1  | 15555550121 | 122 Real St, Nowhere   | Y
 3     | Mary     | Tester2  | 15555550132 | 121 ABC St, Nowhere    | Y
 4     | Jack     | Tester3  | 15555550143 | 120 Rock St, Nowhere   | Y
 5     | Bob      | Tester4  | 15555550154 | 119 Truck St, Nowhere  | N
 6     | Paula    | Tester5  | 1555550165 | 118 Car St, Nowhere    | N
 7     | James    | Tester6  | 1555550176 | 117 Land St, Nowhere   | Y
 8     | Jane     | Tester7  | 1555550187 | 116 Sea St, Nowhere    | Y
 9     | Bill     | Tester8  | 1555550198 | 115 Dock St, Nowhere   | N
 10    | Lucy     | Tester9  | 1555550209 | 114 Beach St, Nowhere  | Y
 11    | Richard  | Tester10 | 1555550210 | 113 Water St, Nowhere  | Y

Selection: 
ACCOUNTS:

 ID    | First    | Last     | Phone      | Address                | Enabled
------|----------|----------|------------|------------------------|---------
 5     | Bob      | Tester4  | 15555550154 | 119 Truck St, Nowhere  | N
 6     | Paula    | Tester5  | 1555550165 | 118 Car St, Nowhere    | N
 9     | Bill     | Tester8  | 1555550198 | 115 Dock St, Nowhere   | N

Selection: Enter search value: 
ACCOUNTS:
 1     | John     | Tester   | 15555550100 | 123 Fake St, Nowhere   | Y
Search again? (Y/[N]) Enter search value: 
ACCOUNTS: [11 rows - all addresses contain "St"]
Search again? (Y/[N]) Enter search value: 
ACCOUNTS: [0 data rows]
Search again? (Y/[N]) 

Selection: Please make a selection between 1-4

Selection: Disconnected.
EXIT_CODE: 0

Devin session

[Colhodm]

lgtm

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