Tag: foreach

Remove remove elements in foreach loop

Table of Contents 1.forEach loop 2. Problem recurrence 3.fail-fast 4.What does remove/add do? 5. Correct operation 1. Directly use the ordinary for loop to operate 2. Directly use Iterator to operate 3. Use the filter provided in Java 8 to filter 4. Directly use fail-safe collection classes 5. It is also possible to use an […]

Mybatis dynamic SQL – use the foreach tag to query data, add batches, modify batches, and delete data

Earlier we introduced the use of Mybatis to complete the addition, deletion, modification and query of data, and also learned how to use the JDK logging system in Mybatis to print logs; in this article we introduce the use of Mybatis’s dynamic SQL to complete query data, batch addition, batch modification, and deletion. data. If […]

HarmonyOS/OpenHarmony application development-ArkTS language rendering control LazyForEach data lazy loading

LazyForEach iterates data on demand from the provided data source and creates the corresponding components during each iteration. When LazyForEach is used in a scrolling container, the framework will create components on demand based on the visible area of the scrolling container. When the component is drawn outside the visible area, the framework will destroy […]

HarmonyOS/OpenHarmony application development – ArkTS language rendering control ForEach loop rendering

ForEach performs loop rendering based on array type data. Note: Starting from API version 9, this interface supports use in ArkTS cards. 1. Interface description ForEach( arr: any[], itemGenerator: (item: any, index?: number) => void, keyGenerator?: (item: any, index?: number) => string ) 2. Use restrictions ForEach must be used inside a container component. The […]

Delete elements in the collection and choose for loop, Iterator or foreach?

Ali’s development manual also clearly states that it is forbidden to use foreach to delete and add List elements. The correct way to delete collection elements is to use iterators (Iterator), the code is as follows: @Test void contextLoads() { List<String> list = new ArrayList<>(4); list.add(“a”); list.add(“ab”); list.add(“abc”); list.add(“abcd”); Iterator<String> iterator = list. iterator(); while […]

Use Lambda expressions, foreach loops, Predicate operations, and Stream operations to traverse Collection collections

Lambda expression traverses Collection collection Java8 adds a default method forEach(Consumer action) to the Iterable interface. The type of parameter required by this method is a functional interface, and the Iterable interface is the parent interface of the Collection interface, so the Collection collection can also directly call this method. When the program calls forEach(Consumer […]

Loop comparison and performance analysis in JS (handwritten forEach and Symbol.iterator)

Directory Loop in JS: for and while Usage of for and while: The performance of for and while: forEach The usage of forEach: Handwritten forEach method: Performance of forEach: for in The usage of for in: Performance of for in: for of iterator iterator: Symbol.iterator property of handwritten array: usage of for performance of for […]