Tag: optional

java8 Optional understanding and examples

A large number of empty codes In practice, if the object is not null, it will cause a null pointer exception. In order to avoid being a pointer, I had to write this very lengthy and ugly null pointer judgment. public void tooMuchNull(Worker worker) { if (worker != null) { Address address=worker.getAddress(); if (address != […]

More elegant empty judgment – use of Optional class

1.Use Optional class is a feature introduced in Java 8. The main problem that the Optional class solves is the notorious NullPointerException. Using it can avoid too many if (obj != null) { } codes in the code and support chaining. programming. Introduction: In projects, we often encounter the need to retrieve a certain value […]

Stream/Optional common methods

Directory Stream 1. Quickly create a list 2. Traverse 3.Filter 4.Group 5. Sum the best value 6.List to Map: 7.map to list 8. Make judgments 9. Merge lists 10. Pagination 11. Sorting 12. Remove duplicates, intercept and skip 13.The difference between map, foreach and peek Optional Stream stream 1. Quickly create a list @Data @AllArgsConstructor […]

[Text feature representation (3)] embedding is used in the QA response system, using Redis as semantic retrieval, and you can use a vector database (optional)

1. What is QA response system QA means question and answer, Q means Question, A means Answer, QA is a very basic and commonly used task in NLP. To put it simply, when a user asks a question, we can find the most similar one from the existing question library and return its answer to […]

[Functional Programming] Lambda, Stream, Optional, method reference, parallel stream

New features of JDK1.8 The main new features in JDK1.8 include: lambda expression Stream Optional functional interface method reference Due to the adaptive parallel flow technology, these advanced features can achieve higher operating efficiency in massive data scenarios without JUC concurrent programming optimization. The number of lines of code is greatly simplified, making it more […]

SYSU SSE algorithm lab5–mandatory and optional problems(English Version) Merging fruits, line segment coverage, milking cows, equally dividing playing cards, and deleting numbers

A-Combine Fruit Problem Description Complete Code #include<iostream> #include<queue> using namespace std; int main() { int n; int x; int res=0; priority_queue<int,vector<int>,greater<int>> heap; // value_type,container_type,compare. // the compare defaults to less<value_type> cin>>n; while(n–){ cin>>x; heap.push(x); } while(heap.size()>1){ int top1=0,top2=0; top1=heap.top(); heap.pop(); top2=heap.top(); heap.pop(); res + =top1 + top2; heap.push(top1 + top2); } cout<<res<<endl; } Code Explanation […]

Optional class in Java language 11

Article directory 1 Optional class 1.1 Why is the Optional class introduced? 1.2 Related APIs 2 API Demo 2.1 Create an object 2.2 Test the API related to creating objects 2.3 Test the API related to obtaining objects 2.4 Test object mapping related APIs 2.5 Testing empty judgment related APIs 2.6 Test filtering API 1 […]

Use Optional to avoid null pointer exceptions elegantly

This article has been included in GitHub. Recommended reading: Java Random Notes WeChat public account: Java Caprice It is not easy to be original, so pay attention to copyright. Please indicate the original author and original link when reprinting Article directory Optional introduction Optional use Create Optional object orElse() and orElseGet() The difference between orElse() […]

java8 Optional understanding and examples

A large number of codes that test for nulls In practice, if the object is not null, it will cause a null pointer exception. In order to avoid being a pointer, I had to write this very lengthy and ugly null pointer judgment. public void tooMuchNull(Worker worker) { if (worker != null) { Address address=worker.getAddress(); […]