synchronous

问题 I need a simple way to wait for setTimeout code to finish executing and then run the code that comes after setTimeout. Now the code after loop containing setTimout is executing before loop/setTimout is finished executing. for(let i = 0; i < 5; i++) { setTimeout(function(){ console.log(i); }, i*1000); } console.log("loop/timeout is done executing"); 回答1: setTimeout is by definition not synchronous - whatever you use to solve the issue will have to be asynchronous, there's no way around that.

问题 I've been reading up on the differences between a HashMap , HashSet , and HashTable . A key thing I've been noticing is that I've seen that HashMap / HashSet are not synchronized while a HashTable is. However in a code base that I've seen before there are several places where a block like this is used: synchronized (hashSet) { //Some code involving the hashset } How is this possible if a HashSet isn't synchronized? Does the synchronized block simply allow us to use a non synchronous data

来源： https://stackoverflow.com/questions/37708207/how-to-synchronously-call-a-set-of-functions-in-javascript

问题 what is the best way to implement RPC style communication (synchronous request/response) with MQTT? Or would it even make sense to put another interface (e.g. REST api) into use? Thanks in advance! 回答1: MQTT is a PUB/SUB system and doesn't lend itself well to RPC. While you could possibly shoehorn something on top of MQTT to simulate the synchronicity required, you are probably better off looking for a system which provides real RPC semantics. That said, depending on your application, you can

问题 The Android Developer documentation does not mention whether the method below (and similar ones) is synchronous or not: Log.i(String tag, String msg) Can anyone shed some light on this ? 回答1: android.util.Log invokes all of its methods on the calling thread. So yes, it is synchronous (and IMO it would be kind of silly if it wasn't). You can find the source code here. 来源： https://stackoverflow.com/questions/11237445/are-android-logging-methods-asynchronous

问题 const params = { TableName: 'item-table', FilterExpression : "#tagname = :itemId", ExpressionAttributeNames: {"#tagname": "itemId"}, ExpressionAttributeValues: {":itemId": "000001"} }; var item =""; dynamo.scan(params, function(err, data) { if (err) { console.error("Unable to query. Error:", JSON.stringify(err, null, 2)); item = err; } else { console.log("Query succeeded."); data.Items.forEach(function(item) { item += item.itemName; }); } return item; }); Scan is not waiting to return the

问题 const params = { TableName: 'item-table', FilterExpression : "#tagname = :itemId", ExpressionAttributeNames: {"#tagname": "itemId"}, ExpressionAttributeValues: {":itemId": "000001"} }; var item =""; dynamo.scan(params, function(err, data) { if (err) { console.error("Unable to query. Error:", JSON.stringify(err, null, 2)); item = err; } else { console.log("Query succeeded."); data.Items.forEach(function(item) { item += item.itemName; }); } return item; }); Scan is not waiting to return the

问题 const params = { TableName: 'item-table', FilterExpression : "#tagname = :itemId", ExpressionAttributeNames: {"#tagname": "itemId"}, ExpressionAttributeValues: {":itemId": "000001"} }; var item =""; dynamo.scan(params, function(err, data) { if (err) { console.error("Unable to query. Error:", JSON.stringify(err, null, 2)); item = err; } else { console.log("Query succeeded."); data.Items.forEach(function(item) { item += item.itemName; }); } return item; }); Scan is not waiting to return the

问题 I have a service to for API call as following, getValue: function(input) { var deferred, url; deferred = $q.defer(); url = "url"; $http.post(url, input).success(function(data, status, headers, config) { return deferred.resolve({ success: true, data: data, status: status, headers: headers, config: config }); }).error(function(data, status, headers, config) { return deferred.resolve({ success: false, data: data, status: status, headers: headers, config: config }); }); return deferred.promise; }

问题 I have a service to for API call as following, getValue: function(input) { var deferred, url; deferred = $q.defer(); url = "url"; $http.post(url, input).success(function(data, status, headers, config) { return deferred.resolve({ success: true, data: data, status: status, headers: headers, config: config }); }).error(function(data, status, headers, config) { return deferred.resolve({ success: false, data: data, status: status, headers: headers, config: config }); }); return deferred.promise; }