Try-catch is meant to help in the exception handling. This means somehow that it will help our system to be more robust: try to recover from an unexpected event.
We suspect something might happen when executing and instruction (sending a message), so it gets enclosed in the try. If that something nearly unexpected happens, we can do something: we write the catch. I don't think we called to just log the exception. I thing the catch block is meant to give us the opportunity of recovering from the error.
Now, let's say we recover from the error because we could fix what was wrong. It could be super nice to do a re-try:
try{ some_instruction(); }
catch (NearlyUnexpectedException e){
fix_the_problem();
retry;
}
This would quickly fall in the eternal loop, but let's say that the fix_the_problem returns true, then we retry. Given that there is no such thing in Java, how would YOU solve this problem? What would be your best design code for solving this?
This is like a philosophical question, given that I already know what I'm asking for is not directly supported by Java.
You need to enclose your try-catch inside a while loop like this: -
int count = 0;
int maxTries = 3;
while(true) {
try {
// Some Code
// break out of loop, or return, on success
} catch (SomeException e) {
// handle exception
if (++count == maxTries) throw e;
}
}
I have taken count and maxTries to avoid running into an infinite loop, in case the exception keeps on occurring in your try block.
Obligatory "enterprisy" solution:
public abstract class Operation {
abstract public void doIt();
public void handleException(Exception cause) {
//default impl: do nothing, log the exception, etc.
}
}
public class OperationHelper {
public static void doWithRetry(int maxAttempts, Operation operation) {
for (int count = 0; count < maxAttempts; count++) {
try {
operation.doIt();
count = maxAttempts; //don't retry
} catch (Exception e) {
operation.handleException(e);
}
}
}
}
And to call:
OperationHelper.doWithRetry(5, new Operation() {
#Override public void doIt() {
//do some stuff
}
#Override public void handleException(Exception cause) {
//recover from the Exception
}
});
As usual, the best design depends on the particular circumstances. Usually though, I write something like:
for (int retries = 0;; retries++) {
try {
return doSomething();
} catch (SomeException e) {
if (retries < 6) {
continue;
} else {
throw e;
}
}
}
You can use AOP and Java annotations from jcabi-aspects (I'm a developer):
#RetryOnFailure(attempts = 3, delay = 5)
public String load(URL url) {
return url.openConnection().getContent();
}
You could also use #Loggable and #LogException annotations.
Although try/catch into while is well-known and good strategy I want to suggest you recursive call:
void retry(int i, int limit) {
try {
} catch (SomeException e) {
// handle exception
if (i >= limit) {
throw e; // variant: wrap the exception, e.g. throw new RuntimeException(e);
}
retry(i++, limit);
}
}
Spring AOP and annotation based solution:
Usage (#RetryOperation is our custom annotation for the job):
#RetryOperation(retryCount = 1, waitSeconds = 10)
boolean someMethod() throws Exception {
}
We'll need two things to accomplish this: 1. an annotation interface, and 2. a spring aspect. Here's one way to implement these:
The Annotation Interface:
import java.lang.annotation.*;
#Target(ElementType.METHOD)
#Retention(RetentionPolicy.RUNTIME)
public #interface RetryOperation {
int retryCount();
int waitSeconds();
}
The Spring Aspect:
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
#Aspect #Component
public class RetryAspect {
private static final Logger LOGGER = LoggerFactory.getLogger(RetryAspect.class);
#Around(value = "#annotation(RetryOperation)")
public Object retryOperation(ProceedingJoinPoint joinPoint) throws Throwable {
Object response = null;
Method method = ((MethodSignature) joinPoint.getSignature()).getMethod();
RetryOperation annotation = method.getAnnotation(RetryOperation.class);
int retryCount = annotation.retryCount();
int waitSeconds = annotation.waitSeconds();
boolean successful = false;
do {
try {
response = joinPoint.proceed();
successful = true;
} catch (Exception ex) {
LOGGER.info("Operation failed, retries remaining: {}", retryCount);
retryCount--;
if (retryCount < 0) {
throw ex;
}
if (waitSeconds > 0) {
LOGGER.info("Waiting for {} second(s) before next retry", waitSeconds);
Thread.sleep(waitSeconds * 1000l);
}
}
} while (!successful);
return response;
}
}
Most of these answers are essentially the same. Mine is also, but this is the form I like
boolean completed = false;
Throwable lastException = null;
for (int tryCount=0; tryCount < config.MAX_SOME_OPERATION_RETRIES; tryCount++)
{
try {
completed = some_operation();
break;
}
catch (UnlikelyException e) {
lastException = e;
fix_the_problem();
}
}
if (!completed) {
reportError(lastException);
}
Use a while loop with local status flag. Initialize the flag as false and set it to true when operation is successful e.g. below:
boolean success = false;
while(!success){
try{
some_instruction();
success = true;
} catch (NearlyUnexpectedException e){
fix_the_problem();
}
}
This will keep retrying until its successful.
If you want to retry only certain number of times then use a counter as well:
boolean success = false;
int count = 0, MAX_TRIES = 10;
while(!success && count++ < MAX_TRIES){
try{
some_instruction();
success = true;
} catch (NearlyUnexpectedException e){
fix_the_problem();
}
}
if(!success){
//It wasn't successful after 10 retries
}
This will try max 10 times if not successful until then an will exit if its successful before hand.
This is an old question but a solution is still relevant. Here is my generic solution in Java 8 without using any third party library:
public interface RetryConsumer<T> {
T evaluate() throws Throwable;
}
public interface RetryPredicate<T> {
boolean shouldRetry(T t);
}
public class RetryOperation<T> {
private RetryConsumer<T> retryConsumer;
private int noOfRetry;
private int delayInterval;
private TimeUnit timeUnit;
private RetryPredicate<T> retryPredicate;
private List<Class<? extends Throwable>> exceptionList;
public static class OperationBuilder<T> {
private RetryConsumer<T> iRetryConsumer;
private int iNoOfRetry;
private int iDelayInterval;
private TimeUnit iTimeUnit;
private RetryPredicate<T> iRetryPredicate;
private Class<? extends Throwable>[] exceptionClasses;
private OperationBuilder() {
}
public OperationBuilder<T> retryConsumer(final RetryConsumer<T> retryConsumer) {
this.iRetryConsumer = retryConsumer;
return this;
}
public OperationBuilder<T> noOfRetry(final int noOfRetry) {
this.iNoOfRetry = noOfRetry;
return this;
}
public OperationBuilder<T> delayInterval(final int delayInterval, final TimeUnit timeUnit) {
this.iDelayInterval = delayInterval;
this.iTimeUnit = timeUnit;
return this;
}
public OperationBuilder<T> retryPredicate(final RetryPredicate<T> retryPredicate) {
this.iRetryPredicate = retryPredicate;
return this;
}
#SafeVarargs
public final OperationBuilder<T> retryOn(final Class<? extends Throwable>... exceptionClasses) {
this.exceptionClasses = exceptionClasses;
return this;
}
public RetryOperation<T> build() {
if (Objects.isNull(iRetryConsumer)) {
throw new RuntimeException("'#retryConsumer:RetryConsumer<T>' not set");
}
List<Class<? extends Throwable>> exceptionList = new ArrayList<>();
if (Objects.nonNull(exceptionClasses) && exceptionClasses.length > 0) {
exceptionList = Arrays.asList(exceptionClasses);
}
iNoOfRetry = iNoOfRetry == 0 ? 1 : 0;
iTimeUnit = Objects.isNull(iTimeUnit) ? TimeUnit.MILLISECONDS : iTimeUnit;
return new RetryOperation<>(iRetryConsumer, iNoOfRetry, iDelayInterval, iTimeUnit, iRetryPredicate, exceptionList);
}
}
public static <T> OperationBuilder<T> newBuilder() {
return new OperationBuilder<>();
}
private RetryOperation(RetryConsumer<T> retryConsumer, int noOfRetry, int delayInterval, TimeUnit timeUnit,
RetryPredicate<T> retryPredicate, List<Class<? extends Throwable>> exceptionList) {
this.retryConsumer = retryConsumer;
this.noOfRetry = noOfRetry;
this.delayInterval = delayInterval;
this.timeUnit = timeUnit;
this.retryPredicate = retryPredicate;
this.exceptionList = exceptionList;
}
public T retry() throws Throwable {
T result = null;
int retries = 0;
while (retries < noOfRetry) {
try {
result = retryConsumer.evaluate();
if (Objects.nonNull(retryPredicate)) {
boolean shouldItRetry = retryPredicate.shouldRetry(result);
if (shouldItRetry) {
retries = increaseRetryCountAndSleep(retries);
} else {
return result;
}
} else {
// no retry condition defined, no exception thrown. This is the desired result.
return result;
}
} catch (Throwable e) {
retries = handleException(retries, e);
}
}
return result;
}
private int handleException(int retries, Throwable e) throws Throwable {
if (exceptionList.contains(e.getClass()) || (exceptionList.isEmpty())) {
// exception is excepted, continue retry.
retries = increaseRetryCountAndSleep(retries);
if (retries == noOfRetry) {
// evaluation is throwing exception, no more retry left. Throw it.
throw e;
}
} else {
// unexpected exception, no retry required. Throw it.
throw e;
}
return retries;
}
private int increaseRetryCountAndSleep(int retries) {
retries++;
if (retries < noOfRetry && delayInterval > 0) {
try {
timeUnit.sleep(delayInterval);
} catch (InterruptedException ignore) {
Thread.currentThread().interrupt();
}
}
return retries;
}
}
Let's have a test case like:
#Test
public void withPredicateAndException() {
AtomicInteger integer = new AtomicInteger();
try {
Integer result = RetryOperation.<Integer>newBuilder()
.retryConsumer(() -> {
int i = integer.incrementAndGet();
if (i % 2 == 1) {
throw new NumberFormatException("Very odd exception");
} else {
return i;
}
})
.noOfRetry(10)
.delayInterval(10, TimeUnit.MILLISECONDS)
.retryPredicate(value -> value <= 6)
.retryOn(NumberFormatException.class, EOFException.class)
.build()
.retry();
Assert.assertEquals(8, result.intValue());
} catch (Throwable throwable) {
Assert.fail();
}
}
A simple way to solve the issue would be to wrap the try/catch in a while loop and maintain a count. This way you could prevent an infinite loop by checking a count against some other variable while maintaining a log of your failures. It isn't the most exquisite solution, but it would work.
In case it's useful, a couple more options to consider, all thrown together (stopfile instead of retries, sleep, continue larger loop) all possibly helpful.
bigLoop:
while(!stopFileExists()) {
try {
// do work
break;
}
catch (ExpectedExceptionType e) {
// could sleep in here, too.
// another option would be to "restart" some bigger loop, like
continue bigLoop;
}
// ... more work
}
If not all exceptions warrant a retry, only some. And if at least one try has to be made, Here is an alternative utility method:
void runWithRetry(Runnable runnable, Class<Exception> exClass, int maxRetries) {
Exception err = null;
do {
maxRetries--;
try {
runnable.run();
err = null;
} catch (Exception e) {
if(exClass.isAssignableFrom(e.getClass())){
err = e;
}else {
throw e;
}
}
} while (err != null && maxRetries > 0);
if (err != null) {
throw err;
}
}
Usage:
runWithRetry(() -> {
// do something
}, TimeoutException.class, 5)
All a Try-Catch does is allow your program to fail gracefully. In a catch statement, you generally try to log the error, and maybe roll back changes if you need to.
bool finished = false;
while(finished == false)
{
try
{
//your code here
finished = true
}
catch(exception ex)
{
log.error("there was an error, ex");
}
}
Use a do-while to design re-try block.
boolean successful = false;
int maxTries = 3;
do{
try {
something();
success = true;
} catch(Me ifUCan) {
maxTries--;
}
} while (!successful || maxTries > 0)
Here a reusable and more generic approach for Java 8+ that does not require external libraries:
public interface IUnreliable<T extends Exception>
{
void tryRun ( ) throws T;
}
public static <T extends Exception> void retry (int retryCount, IUnreliable<T> runnable) throws T {
for (int retries = 0;; retries++) {
try {
runnable.tryRun();
return;
} catch (Exception e) {
if (retries < retryCount) {
continue;
} else {
throw e;
}
}
}
}
Usage:
#Test
public void demo() throws IOException {
retry(3, () -> {
new File("/tmp/test.txt").createNewFile();
});
}
You can use https://github.com/bnsd55/RetryCatch
Example:
RetryCatch retryCatchSyncRunnable = new RetryCatch();
retryCatchSyncRunnable
// For infinite retry times, just remove this row
.retryCount(3)
// For retrying on all exceptions, just remove this row
.retryOn(ArithmeticException.class, IndexOutOfBoundsException.class)
.onSuccess(() -> System.out.println("Success, There is no result because this is a runnable."))
.onRetry((retryCount, e) -> System.out.println("Retry count: " + retryCount + ", Exception message: " + e.getMessage()))
.onFailure(e -> System.out.println("Failure: Exception message: " + e.getMessage()))
.run(new ExampleRunnable());
Instead of new ExampleRunnable() you can pass your own anonymous function.
Simplifying #ach's previous solution into one file and using functional interfaces.
public class OperationHelper {
public static void doWithRetry(int maxAttempts, Runnable operation, Consumer<Exception> handle) {
for (int count = 0; count < maxAttempts; count++) {
try {
operation.run();
count = maxAttempts; //don't retry
} catch (Exception e) {
handle.accept(e);
}
}
}
}
simple
int MAX = 3;
int count = 0;
while (true) {
try {
...
break;
} catch (Exception e) {
if (count++ < MAX) {
continue;
}
...
break;
}
}
https://onlinegdb.com/a-7RsL1Gh
public void doSomething() throws Exception{
final int MAX_TRIES = 10;
int count = 0;
while(count++ < MAX_TRIES){
try{
System.out.println("trying");
causeIssue(count); // throws error/exception till count 2
System.out.println("trying successful");
break; // break on success
} catch (Exception e){
System.out.println("caught, logging Exception:" + count);
} catch (Error e){
System.out.println("caught, logging Error:" + count);
}
}
}
Output:
trying
caught, logging Error:1
trying
caught, logging Error:2
trying
trying successful
I know there are already many similar answers here, and mine is not much different, but I will post it anyway because it deals with a specific case/issue.
When dealing with the facebook Graph API in PHP you sometimes get an error, but immediately re-trying the same thing will give a positive result (for various magical Internet reasons that are beyond the scope of this question). In this case there is no need to fix any error, but to simply try again because there was some kind of "facebook error".
This code is used immediately after creating a facebook session:
//try more than once because sometimes "facebook error"
$attempt = 3;
while($attempt-- > 0)
{
// To validate the session:
try
{
$facebook_session->validate();
$attempt = 0;
}
catch (Facebook\FacebookRequestException $ex)
{
// Session not valid, Graph API returned an exception with the reason.
if($attempt <= 0){ echo $ex->getMessage(); }
}
catch (\Exception $ex)
{
// Graph API returned info, but it may mismatch the current app or have expired.
if($attempt <= 0){ echo $ex->getMessage(); }
}
}
Also, by having the for loop count down to zero ($attempt--) it makes it pretty easy to change the number of attempts in the future.
following is my solution with very simple approach!
while (true) {
try {
/// Statement what may cause an error;
break;
} catch (Exception e) {
}
}
Im not sure if this is the "Professional" way to do it and i'm not entirely sure if it works for everything.
boolean gotError = false;
do {
try {
// Code You're Trying
} catch ( FileNotFoundException ex ) {
// Exception
gotError = true;
}
} while ( gotError = true );
https://github.com/tusharmndr/retry-function-wrapper/tree/master/src/main/java/io
int MAX_RETRY = 3;
RetryUtil.<Boolean>retry(MAX_RETRY,() -> {
//Function to retry
return true;
});
The issue with the remaining solutions is that, the correspondent function tries continuously without a time interval in-between, thus over flooding the stack.
Why not just trying only every second and ad eternum?
Here a solution using setTimeout and a recursive function:
(function(){
try{
Run(); //tries for the 1st time, but Run() as function is not yet defined
}
catch(e){
(function retry(){
setTimeout(function(){
try{
console.log("trying...");
Run();
console.log("success!");
}
catch(e){
retry(); //calls recursively
}
}, 1000); //tries every second
}());
}
})();
//after 5 seconds, defines Run as a global function
var Run;
setTimeout(function(){
Run = function(){};
}, 5000);
Replace the function Run() by the function or code that you'd like to retry every second.
Give it a try using springs #Retryable annotation , the below method will retry for 3 attempts when RuntimeException occurs
#Retryable(maxAttempts=3,value= {RuntimeException.class},backoff = #Backoff(delay = 500))
public void checkSpringRetry(String str) {
if(StringUtils.equalsIgnoreCase(str, "R")) {
LOGGER.info("Inside retry.....!!");
throw new RuntimeException();
}
}
Below snippet execute some code snippet. If you got any error while executing the code snippet, sleep for M milliseconds and retry. Reference link.
public void retryAndExecuteErrorProneCode(int noOfTimesToRetry, CodeSnippet codeSnippet, int sleepTimeInMillis)
throws InterruptedException {
int currentExecutionCount = 0;
boolean codeExecuted = false;
while (currentExecutionCount < noOfTimesToRetry) {
try {
codeSnippet.errorProneCode();
System.out.println("Code executed successfully!!!!");
codeExecuted = true;
break;
} catch (Exception e) {
// Retry after 100 milliseconds
TimeUnit.MILLISECONDS.sleep(sleepTimeInMillis);
System.out.println(e.getMessage());
} finally {
currentExecutionCount++;
}
}
if (!codeExecuted)
throw new RuntimeException("Can't execute the code within given retries : " + noOfTimesToRetry);
}
Here is my solution similar to some others can wrap a function, but allows you to get the functions return value, if it suceeds.
/**
* Wraps a function with retry logic allowing exceptions to be caught and retires made.
*
* #param function the function to retry
* #param maxRetries maximum number of retires before failing
* #param delay time to wait between each retry
* #param allowedExceptionTypes exception types where if caught a retry will be performed
* #param <V> return type of the function
* #return the value returned by the function if successful
* #throws Exception Either an unexpected exception from the function or a {#link RuntimeException} if maxRetries is exceeded
*/
#SafeVarargs
public static <V> V runWithRetriesAndDelay(Callable<V> function, int maxRetries, Duration delay, Class<? extends Exception>... allowedExceptionTypes) throws Exception {
final Set<Class<? extends Exception>> exceptions = new HashSet<>(Arrays.asList(allowedExceptionTypes));
for(int i = 1; i <= maxRetries; i++) {
try {
return function.call();
} catch (Exception e) {
if(exceptions.contains(e.getClass())){
// An exception of an expected type
System.out.println("Attempt [" + i + "/" + maxRetries + "] Caught exception [" + e.getClass() + "]");
// Pause for the delay time
Thread.sleep(delay.toMillis());
}else {
// An unexpected exception type
throw e;
}
}
}
throw new RuntimeException(maxRetries + " retries exceeded");
}
This Solution allows you to configure a reusable functionality for retrying based on certain exception without using any external libraries
// Create a Function that suits your need .
#FunctionalInterface
public interface ThrowableBiFunction<U,T,R> {
R apply(U u ,T t) throws Exception;
}
//Here's the crux of the solution
public interface ExceptionRetryable<T, U, R> {
int getRetries();
List<Class<? extends Exception>> getRetryableExceptions();
default R execute(ThrowableBiFunction<T, U, R> function, T t, U u) throws Exception {
int numberOfRetries = getRetries();
return execute(function, t, u, numberOfRetries);
}
default R execute(ThrowableBiFunction<T, U, R> function, T t, U u, int retryCount) throws Exception {
try {
log.info(" Attempting to execute ExceptionRetryable#execute ,Number of remaining retries {} ",retryCount);
return function.apply(t, u);
} catch (Exception e) {
log.info(" error occurred in ExceptionRetryable#execute",e);
if (retryCount == 0)
throw e;
for (Class exp : getRetryableExceptions()) {
if (e.getClass() == exp) {
return execute(function, t, u, retryCount - 1);
}
}
throw e;
}
}
}
// create an implementation for exception retryable
public class TestRetryable implements ExceptionRetryable<String, String, List<String>> {
#Override
public int getRetries() {
return 10;
}
#Override
public List<Class<? extends Exception>> getRetryableExceptions() {
return Arrays.asList(new Exception1().getClass(), new Exception2().getClass());
;
}
}
// Finally create a ThrowableBiFunction that encapsulates that piece of code that needs to be retried on exception and an instance of ExceptionRetryable
TestRetryable retryable = new TestRetryable();
ThrowableBiFunction<Integer,Long, String> testRetrablefcn = { i, l ->
// your code goes here
};
Integer i = 0;
Long l = 1l;
String output = testRetrablefcn.execute(testRetrablefcn,i,l);
Production ready code:
#FunctionalInterface
public interface Operation {
void doCall() throws IOException;
default void handleException(Exception e) {
//Your custom default implementation
}
public class OperationHelper {
public static void doWithRetry(int maxAttempts, Operation operation) {
for (int count = 0; count <= maxAttempts; count++) {
try {
operation.doCall();
return;
} catch (Exception e) {
if (count == maxAttempts) {
e.printStackTrace();
return;
} else {
operation.handleException(e);
}
}
}
}
}
Usage with default implementation in code:
OperationHelper.doWithRetry(10,
() -> //do your job );
Usage when custom exception handle is needed:
OperationHelper.doWithRetry(10, new Operation() {
#Override public void doIt() {
//do some stuff
}
#Override public void handleException(Exception cause) {
//recover from the Exception
}
});
So, I'm working on a plugin at work and I've run into a situation where I could use a ContentProposalAdapter to my benefit. Basically, a person will start typing in someone's name and then a list of names matching the current query will be returned in a type-ahead manner (a la Google). So, I created a class IContentProposalProvider which, upon calling it's getProposals() method fires off a thread which handles getting the proposals in the background. The problem I am having is that I run into a race condition, where the processing for getting the proposals via HTTP happens and I try to get the proposals before they have actually been retrieved.
Now, I'm trying not to run into an issue of Thread hell, and that isn't getting me very far anyway. So, here is what I've done so far. Does anyone have any suggestions as to what I can do?
public class ProfilesProposalProvider implements IContentProposalProvider, PropertyChangeListener {
private IContentProposal[] props;
#Override
public IContentProposal[] getProposals(String arg0, int arg1) {
Display display = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell().getDisplay();
RunProfilesJobThread t1 = new RunProfilesJobThread(arg0, display);
t1.run();
return props;
}
#Override
public void propertyChange(PropertyChangeEvent arg0) {
if (arg0.getSource() instanceof RunProfilesJobThread){
RunProfilesJobThread thread = (RunProfilesJobThread)arg0.getSource();
props = thread.getProps();
}
}
}
public class RunProfilesJobThread extends Thread {
private ProfileProposal[] props;
private Display display;
private String query;
public RunProfilesJobThread(String query, Display display){
this.query = query;
}
#Override
public void run() {
if (!(query.equals(""))){
GetProfilesJob job = new GetProfilesJob("profiles", query);
job.schedule();
try {
job.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
GetProfilesJobInfoThread thread = new GetProfilesJobInfoThread(job.getResults());
try {
thread.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
props = thread.getProps();
}
}
public ProfileProposal[] getProps(){
return props;
}
}
public class GetProfilesJobInfoThread extends Thread {
private ArrayList<String> names;
private ProfileProposal[] props;
public GetProfilesJobInfoThread(ArrayList<String> names){
this.names = names;
}
#Override
public void run() {
if (names != null){
props = new ProfileProposal[names.size()];
for (int i = 0; i < props.length - 1; i++){
ProfileProposal temp = new ProfileProposal(names.get(i), names.get(i));
props[i] = temp;
}
}
}
public ProfileProposal[] getProps(){
return props;
}
}
Ok, i'll try it...
I haven't tried to run it, but it should work more or less. At least it's a good start. If you have any questions, feel free to ask.
public class ProfilesProposalProvider implements IContentProposalProvider {
private List<IContentProposal> proposals;
private String proposalQuery;
private Thread retrievalThread;
public void setProposals( List<IContentProposal> proposals, String query ) {
synchronized( this ) {
this.proposals = proposals;
this.proposalQuery = query;
}
}
public IContentProposal[] getProposals( String contents, int position ) {
// Synchronize incoming thread and retrieval thread, so that the proposal list
// is not replaced while we're processing it.
synchronized( this ) {
/**
* Get proposals if query is longer than one char, or if the current list of proposals does with a different
* prefix than the new query, and only if the current retrieval thread is finished.
*/
if ( retrievalThread == null && contents.length() > 1 && ( proposals == null || !contents.startsWith( proposalQuery ) ) ) {
getProposals( contents );
}
/**
* Select valid proposals from retrieved list.
*/
if ( proposals != null ) {
List<IContentProposal> validProposals = new ArrayList<IContentProposal>();
for ( IContentProposal prop : proposals ) {
if(prop == null) {
continue;
}
String propVal = prop.getContent();
if ( isProposalValid( propVal, contents )) {
validProposals.add( prop );
}
}
return validProposals.toArray( new IContentProposal[ validProposals.size() ] );
}
}
return new IContentProposal[0];
}
protected void getProposals( final String query ) {
retrievalThread = new Thread() {
#Override
public void run() {
GetProfilesJob job = new GetProfilesJob("profiles", query);
job.schedule();
try {
job.join();
ArrayList<String> names = job.getResults();
if (names != null){
List<IContentProposal> props = new ArrayList<IContentProposal>();
for ( String name : names ) {
props.add( new ProfileProposal( name, name ) );
}
setProposals( props, query );
}
} catch (InterruptedException e) {
e.printStackTrace();
}
retrievalThread = null;
}
};
retrievalThread.start();
}
protected boolean isProposalValid( String proposalValue, String contents ) {
return ( proposalValue.length() >= contents.length() && proposalValue.substring(0, contents.length()).equalsIgnoreCase(contents));
}
}