we chain three operations: first, themapmethod transforms each string to uppercase with a method reference (String::toUpperCase); next, thefiltermethod selects only those strings exceeding five characters in length; finally, theforEachmethod prints the resulting elements to the console. This demonst...
for(int j = 0; j < size; j ++){ result.add(state.testData.get(j)); } return result; } 然后,查看性能比较: Benchmark Mode Cnt Score Error Units TestLoopPerformance.forCStyle avgt 200 18.068 ± 0.074 ms/op TestLoopPerformance.forEach avgt 200 30.566 ± 0.165 ms/op TestLoopPerforman...
MyBatis has to 1) evaluate the foreach part and 2) parse the statement string to build parameter mapping [1] on every execution of this statement.
streamMultiThread avgt 200 79.433± 0.747 ms/op TestLoopPerformance.streamSingleThread avgt 200 37.779± 0.485 ms/op 使用C 语言形式的 for 循环,JVM 每次仅仅增加一个数字,然后直接从内存里读出数据。这使得它非常迅速。但是 forEach 就大不一样,根据 StackOverFlow 的这篇回答(https://stackoverflow.com...
近日,项目中有一个耗时较长的Job存在CPU占用过高的问题,经排查发现,主要时间消耗在往MyBatis中批量插入数据。mapper configuration是用foreach循环做的,差不多是这样。(由于项目保密,以下代码均为自己手写的demo代码) <insert id="batchInsert" parameterType="java.util.List"> ...
publicclassPerformance{publicstaticvoidmain(String[]args){List<String>list=getLoopList();normalBeforeLoop(list);normalAfterLoop(list);notNormalAfterLoop(list);}privatestaticvoidnotNormalAfterLoop(List<String>list){long a=System.currentTimeMillis();list.stream().parallel().forEach(System.out::print...
更简洁，更重要的是，foreach实际上就是使用的迭代器，因此，code时始终使用foreach代替一般的for loop...
TestLoopPerformance.forEach avgt 200 4.498 ± 0.026 ms/op HashMap(HashSetusesHashMap<E,Object>) isn't designed for iterating all items. The fastest way to iterate overHashMapis a combination ofIteratorand the C styleforloop, because JVM doesn't have to callhasNext(). ...
* {@linkFuture#isDone} is {@codetrue} for each * element of the returned list. * Note that a completed task could have * terminated either normally or by throwing an exception. * The results of this method are undefined if the given * collection ...
Instead of each String object pointing to its own character array, identical String objects can point to and share the same character array. See the option -XX:+UseStringDeduplication for more information.Bug FixesThe following are some of the notable bug fixes in this release:Area: tools/java...