exceptions: Java exception handling companion code (suppression, chaining, cost)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01KqJyCidz3ZgRyHABv2GVJh

exceptions/output/01-suppressed.txt

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+=== try/finally: the close() exception replaces the query() exception ===
+caught: java.lang.IllegalArgumentException: close failed on db-1
+suppressed count: 0
+
+=== try-with-resources: query() exception wins, close() exception is attached ===
+caught: java.lang.IllegalStateException: query failed on db-1
+suppressed count: 1
+  suppressed: java.lang.IllegalArgumentException: close failed on db-1
+
+=== two resources: closed in reverse order, each failure is suppressed ===
+caught: java.lang.IllegalStateException: query failed on B
+  suppressed: java.lang.IllegalArgumentException: close failed on B
+  suppressed: java.lang.IllegalArgumentException: close failed on A
+
+=== what printStackTrace() shows for suppressed exceptions ===
+java.lang.IllegalStateException: query failed on db-1
+	at com.ankurm.exceptions.SuppressedDemo$Conn.query(SuppressedDemo.java:9)
+	Suppressed: java.lang.IllegalArgumentException: close failed on db-1
+		at com.ankurm.exceptions.SuppressedDemo$Conn.close(SuppressedDemo.java:10)

exceptions/output/02-chaining.txt

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+=== wrapped WITH the cause ===
+getMessage(): could not load order 42
+getCause():   java.lang.IllegalStateException: connection reset by peer
+java.lang.RuntimeException: could not load order 42
+	at com.ankurm.exceptions.ChainingDemo.serviceGood(ChainingDemo.java:10)
+	at com.ankurm.exceptions.ChainingDemo.print(ChainingDemo.java:20)
+	at com.ankurm.exceptions.ChainingDemo.main(ChainingDemo.java:30)
+Caused by: java.lang.IllegalStateException: connection reset by peer
+	at com.ankurm.exceptions.ChainingDemo.dao(ChainingDemo.java:6)
+	at com.ankurm.exceptions.ChainingDemo.serviceGood(ChainingDemo.java:9)
+	... 2 more
+
+=== wrapped WITHOUT the cause (message copied as a string) ===
+getMessage(): could not load order 42: connection reset by peer
+getCause():   null
+java.lang.RuntimeException: could not load order 42: connection reset by peer
+	at com.ankurm.exceptions.ChainingDemo.serviceBad(ChainingDemo.java:15)
+	at com.ankurm.exceptions.ChainingDemo.print(ChainingDemo.java:20)
+	at com.ankurm.exceptions.ChainingDemo.main(ChainingDemo.java:31)
+

exceptions/output/03-checked-vs-unchecked.txt

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+=== which are checked? ===
+Exception                    CHECKED    Exception -> Throwable -> Object
+IOException                  CHECKED    IOException -> Exception -> Throwable -> Object
+InterruptedException         CHECKED    InterruptedException -> Exception -> Throwable -> Object
+RuntimeException             unchecked  RuntimeException -> Exception -> Throwable -> Object
+IllegalArgumentException     unchecked  IllegalArgumentException -> RuntimeException -> Exception -> Throwable -> Object
+NullPointerException         unchecked  NullPointerException -> RuntimeException -> Exception -> Throwable -> Object
+Error                        unchecked  Error -> Throwable -> Object
+OutOfMemoryError             unchecked  OutOfMemoryError -> VirtualMachineError -> Error -> Throwable -> Object
+StackOverflowError           unchecked  StackOverflowError -> VirtualMachineError -> Error -> Throwable -> Object
+
+=== checked exception inside a stream lambda: wrap in UncheckedIOException ===
+contents of a.txt
+caught: java.io.UncheckedIOException: java.io.IOException: cannot read bad.txt
+original cause: java.io.IOException: cannot read bad.txt

exceptions/output/04-custom-hierarchy.txt

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+404-ish  -> NOT_FOUND: order 42 does not exist
+generic  -> CONFLICT: version mismatch
+ControlFlowException stack trace length: 0
+RuntimeException stack trace length:     1
+ControlFlowException suppressed count after addSuppressed(): 0

exceptions/output/05-finally-trap.txt

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+swallowed() returned -1 - the IllegalStateException never reached the caller

exceptions/output/06-lambda-checked-compile-error.txt

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+src/broken/LambdaChecked.java:8: error: unreported exception IOException; must be caught or declared to be thrown
+        Stream.of("a", "b").map(n -> read(n)).forEach(System.out::println);
+                                         ^
+1 error

exceptions/output/07-UnreachableCatch-compile-error.txt

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+src/broken/UnreachableCatch.java:8: error: exception IOException is never thrown in body of corresponding try statement
+        } catch (IOException e) {
+          ^
+1 error

exceptions/output/08-MultiCatchSubclass-compile-error.txt

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+src/broken/MultiCatchSubclass.java:8: error: Alternatives in a multi-catch statement cannot be related by subclassing
+        try { f(); } catch (FileNotFoundException | IOException e) { }
+                                                    ^
+  Alternative FileNotFoundException is a subclass of alternative IOException
+1 error

exceptions/output/09-WiderOverride-compile-error.txt

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+src/broken/WiderOverride.java:7: error: run() in Impl cannot implement run() in Task
+        public void run() throws IOException { throw new IOException(); }
+                    ^
+  overridden method does not throw IOException
+1 error

exceptions/output/10-omit-stack-trace-in-fast-throw.txt

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+$ java OmitStackTraceDemo
+the ArithmeticException at iteration 1127 had an EMPTY stack trace
+
+$ java -XX:-OmitStackTraceInFastThrow OmitStackTraceDemo
+every ArithmeticException still carried a stack trace in 300000 throws

exceptions/output/11-jmh-raw.txt

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+Benchmark                               (depth)  Mode  Cnt     Score     Error  Units
+ExceptionCostBenchmark.noStackTrace           1  avgt    5     9.810 ±   2.142  ns/op
+ExceptionCostBenchmark.noStackTrace          10  avgt    5   345.467 ±  24.683  ns/op
+ExceptionCostBenchmark.noStackTrace          50  avgt    5  1610.131 ± 148.390  ns/op
+ExceptionCostBenchmark.normalException        1  avgt    5   989.076 ± 239.352  ns/op
+ExceptionCostBenchmark.normalException       10  avgt    5  1589.303 ±  47.103  ns/op
+ExceptionCostBenchmark.normalException       50  avgt    5  4137.934 ± 462.310  ns/op
+ExceptionCostBenchmark.preallocated           1  avgt    5     3.240 ±   0.190  ns/op
+ExceptionCostBenchmark.preallocated          10  avgt    5   336.605 ±  33.790  ns/op
+ExceptionCostBenchmark.preallocated          50  avgt    5  1578.591 ±  74.969  ns/op
+ExceptionCostBenchmark.returnCode             1  avgt    5     1.101 ±   0.033  ns/op
+ExceptionCostBenchmark.returnCode            10  avgt    5    10.786 ±   0.301  ns/op
+ExceptionCostBenchmark.returnCode            50  avgt    5    52.932 ±   1.374  ns/op

exceptions/output/12-deep-trace.txt

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+frames the program actually descended: more than 1024 (true)
+getStackTrace().length: 1024

exceptions/output/13-tests.txt

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+-------------------------------------------------------------------------------
+Test set: com.ankurm.exceptions.ExceptionBehaviourTest
+-------------------------------------------------------------------------------
+Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.105 s -- in com.ankurm.exceptions.ExceptionBehaviourTest

exceptions/output/14-jvm-flags.txt

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+ int MaxJavaStackTraceDepth = 1024 {product} {default}
+ bool OmitStackTraceInFastThrow = true {product} {default}
+ bool StackTraceInThrowable = true {product} {default}