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JavaSE_04 [ process control statement ] Today's content for loop statementwhile loop statementdo... while loop statementbreakcontinue Learning objectives Understand the format and execution process of for statement Understand the format and execution flow of while statement Understand the format and execution flow of do... while statement ...

I. review 1.HashMap set Features: A. the data structure is also a Hash table structure B. It is unsafe in multithreading C. the initialization capacity of the default array is 16 2. Comparison between HashMap and HashSet The same point: they are stored in hash table structure Differences: The bottom layer of A.HashSet is imp ...

Detailed explanation of JAVA multithreading (II) III Thread state 1. Five states 2. Thread method methodexplainsetPriority(int newPriority)Change the priority of a threadstatic void sleep(long millis)Hibernates the currently executing thread for the specified number of millisecondsvoid join()Wait for the thread to terminatestatic voi ...

⭐ ♪ previous words ⭐ ️ This article introduces you to Java syntax - generics and wildcards. Generics and wildcards are very abstract concepts. In short, both can pass types as "parameters". However, generics are used when you know what type to pass in, while wildcards are used when you are not sure what type to pass in, This articl ...

if selection structure 1. Classification if single choice structureif double choice structureif multiple selection structure 2. if single choice structure Syntax: if (conditional expression){ }Note: the code in curly braces (code block) will be executed only when the return value of the conditional expression is true 3. if double choice stru ...

Implement the simplest deadlock (Java version) ```java /** * @author wall * @date 2019/7/29 16:42 * @description Implement A deadlock: thread A obtains the lock held by thread B, and thread B obtains the lock held by thread A */ public class DeadLock { //Define two locks private static ReentrantLock lockA = new ReentrantLock(); ...

1, TreeSet 1. The bottom layer of TreeSet set is actually a TreeMap; At the bottom of the TreeMap set is a binary tree 2. The elements put into the TreeSet set are equivalent to the key part of the TreeMap set. 3. TreeSet set storage element features: unordered and non repeatable, but the stored elements can be automatically sorted in size o ...

Three characteristics of object-oriented: encapsulation, inheritance and polymorphism encapsulation In order to ensure the security of variables, we use encapsulation, do not care about the specific implementation details, but only access the members of the class through external excuses. public class Student { private String name; p ...

Java collection framework (III) Map interface Characteristics of Map implementation class Map: double column data, which stores the data of key value pairs, similar to the function of high school, y=f (x) Implementation class: HashMap: as the main implementation class of Map; Unsafe thread and high efficiency; null key s and value s ca ...

Today, when studying the Java concurrency container and framework, we can see why we should use ConcurrentHashMap. One reason is: thread unsafe HashMap. HashMap will cause a dead loop when executing put operation concurrently, because multithreading will cause the Entry linked list of HashMap to form a ring data structure and fall into a dead l ...