Develop Reference

This method throws two different exceptions. How could man catch the two exceptions and prints exception catched for both exception types to console?

public class CatchingExceptions {
private int erroneousMethod(int p) {
if (p == 0) {
throw new IllegalArgumentException();
}
int x = 0x01;
return p / (x >> Math.abs(p)); // this line will throw!
}
The task is to implement the following method to catch and print the two exceptions.
public void catchExceptions(int passthrough) {
erroneousMethod(passthrough); // will throw!
try{
????
} catch (IllegalArgumentException e){
System.out.println("???? ");
}
}

Call the method inside the try block:
public void catchExceptions(int passthrough) {
try{
erroneousMethod(passthrough);
} catch (RuntimeException e) { // catches all unchecked exceptions
String message = e.getMessage() == null ? "" : (": " + e.getMessage());
System.out.println(e.getClass().getSimpleName() + ": " + message);
}
}

Flux getting stuck in case of any java.lang.Error(OOM)

In flux whenever there is OOM the whole process is getting stuck until we kill it manually. I have created an example to simulate it. Please refer the following code:
#Test
public void test_Flux() {
Flux.range(1, 30)
.parallel(6)
.runOn(Schedulers.fromExecutor(Executors.newFixedThreadPool(6)))
.doOnNext(this::writeValues)
.sequential()
.blockLast();
}
private void writeValues(int val) {
if (val == 10) {
throw new OutOfMemoryError("failed here");
// throw new RuntimeException("failed here");
}
System.out.println("the thread name is :" + Thread.currentThread().getName() + " val is :" + val);
sleep(3);
}
private void sleep(int i) {
try {
Thread.sleep(i * 1000L);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new RuntimeException(e);
}
}
Can we crash here instead of getting stuck?

Execution order of callables is not consistent

I have this code where I execute sets of callables, I need one set to finish all it's work before triggering the next set. This code seems to work fine but sometimes next set would start running before time. What is wrong here?
private void executeSubGraph(QuestExecutionContext ctx, Set<Activity> subGraph, int progressAfterRan) {
ExecutorService pool = Executors.newFixedThreadPool(16);
subGraph.forEach(a -> {
ActivityRunner<? extends Activity> runner = activityRunnerFactory.getRunner(ctx, a);
if (runner != null) {
Callable<List<PortValuePart>> runnerCallable = () -> {
try {
LOG.info("Running {} in {}", a, a.getClass() );
List<PortValuePart> result = runner.call();
LOG.info("Result of {} in {} is {}", a, a.getClass(), result);
if (result != null) {
result.forEach(r -> resultProcessor.processResult(new PortValuePartEnvelope(r)));
}
return result;
} catch (Exception e) {
LOG.warn("Exception for {} in {}", a, runner.getClass(), e);
resultProcessor.processResult(Progress.failed(ctx.getId(), e));
throw new RuntimeException(e);
}
};
Future<List<PortValuePart>> p = pool.submit(runnerCallable);
} else {
LOG.warn("No runner found for activity {}", a);
resultProcessor.processResult(Progress.failed(ctx.getId(), new RuntimeException("No runner found for activity " + a)));
throw new RuntimeException("No runner found for activity " + a);
}
});
pool.shutdown();
try {
pool.awaitTermination(WAIT_TIME_MILLIS, TimeUnit.MILLISECONDS);
resultProcessor.processResult(Progress.running(ctx.getId(), progressAfterRan));
} catch (InterruptedException e) {
throw new PlatformException("Execution interrupted.");
}
}

Note that ExecutorService.awaitTermination doesn't throw an exception if it times out; it just returns false. If you want to make sure that the next calls don't run concurrently with these ones, you should probably use the return value, and maybe throw an exception (and kill the tasks) if it's taking way too long.

How to throw an error with transaction java

I'm doing something like this:
try {
client.restoreFromClusterSnapshot(req);
} catch (AmazonRedshiftException e) {
txUtils.execute((ts) -> {
redshiftDto.setStatus(ResourceStatus.FAILED);
redshiftDto.setStatusDetails(e.getMessage());
redshiftDto.setUpdatedOn(Timestamp.from(Instant.now()));
this.rdao.merge(redshiftDto);
return null;
});
LOGGER.error("CANNOT START REDSHIFT- " + e.getErrorMessage());
throw new AmazonRedshiftException( "CANNOT START REDSHIFT- "
+ e.getErrorMessage());
}
In this code, I'm not able to set database variable if I'm throwing an error because it is terminating my transaction. If I'll comment that throw it will work and my database value will be set. But I'll not able to throw anything. How can I do both- (throwing and setting value in DB)

What I'd do is make use of the finally clause.
AmazonRedshiftException exception = null;
try {
cluster = client.restoreFromClusterSnapshot(req);
} catch (AmazonRedshiftException e) {
exception = e;
LOGGER.error("CANNOT START REDSHIFT- " + e.getErrorMessage());
throw new AmazonRedshiftException( "CANNOT START REDSHIFT- "
+ e.getErrorMessage());
} finally {
if(exception != null) {
txUtils.execute((ts) -> {
redshiftDto.setStatus(ResourceStatus.FAILED);
redshiftDto.setStatusDetails(exception.getMessage());
redshiftDto.setUpdatedOn(Timestamp.from(Instant.now()));
this.rdao.merge(redshiftDto);
return null;
});
}
}

Handling iBatis NestedSQLException

I have a java app that try to insert a row into the table and com.​ibatis.​common.​jdbc.​exception.NestedSQLException is thrown with the Cause com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException
When I try to insert dublicate data for a unique-key constraint.
How do I catch that exception?

To get to the root cause you can do something like this:
try {
//insert
} catch (NestedSQLException e) {
Throwable t = e;
while(t.getCause() != null) {
t = t.getCause();
}
//in your situation, now t should be MySQLIntegrityConstraintViolationException
if (t instanceOf MySQLIntegrityConstraintViolationException) {
//do something
}
}

In case it helps someone. #tibtof's is correct and got me to:
public int insert(MyObject myObject) {
int recCount = -1;
try {
recCount = insert(myObject, MyObjectMapper.class);
} catch (Throwable e) {
Throwable t = e;
while (t.getCause() != null) {
t = t.getCause();
if (t instanceof SQLIntegrityConstraintViolationException) {
// get out gracefully.
recCount = -1;
return recCount;
}
}
//Something else wicked wrong happened.
LogUtils.error(log, e.getMessage(), e);
throw new RuntimeException(e.getMessage(), e);
}
return webGroup.getWebGroupId().intValue();
}