Java 基础技能：掌握 Java 8-21 核心语法、面向对象编程、集合框架与流 API

java-fundamentals by pluginagentmarketplace/custom-plugin-java

229 周安装量

27 GitHub Stars

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安装命令

npx skills add https://github.com/pluginagentmarketplace/custom-plugin-java --skill java-fundamentals

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🇨🇳中文介绍

Java 基础技能

掌握核心 Java 编程及生产级代码模式。

概述

本技能涵盖 Java 基础，包括 Java 8-21 的语法、面向对象编程、集合、流 API 和异常处理。

使用场景

当您需要时使用此技能：

编写简洁、地道的 Java 代码
遵循面向对象原则设计类
选择合适的集合类型
实现函数式编程模式
正确处理异常

涵盖主题

核心语法 (Java 8-21)

变量、数据类型、运算符
控制流、方法、类
记录类 (Java 16+)、密封类 (Java 17+)
模式匹配 (Java 21+)

面向对象编程

类、继承、多态
接口和抽象类
SOLID 原则

集合框架

List: ArrayList, LinkedList
Set: HashSet, TreeSet
Map: HashMap, ConcurrentHashMap
Queue: ArrayDeque, PriorityQueue

流 API

filter, map, flatMap, reduce, collect
Optional 处理
并行流

异常处理

受检异常与非受检异常
Try-with-resources
自定义异常

快速参考

// Record (Java 16+)
public record User(String name, String email) {}

// Pattern matching (Java 21)
String format(Object obj) {
    return switch (obj) {
        case Integer i -> "Int: %d".formatted(i);
        case String s -> "String: %s".formatted(s);
        default -> obj.toString();
    };
}

// Stream operations
List<String> names = users.stream()
    .filter(User::isActive)
    .map(User::getName)
    .sorted()
    .toList();

// Optional handling
String name = Optional.ofNullable(user)
    .map(User::getName)
    .orElse("Unknown");

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需求	使用	原因
索引访问	ArrayList	O(1) 随机访问
唯一元素	HashSet	O(1) 包含检查
排序唯一	TreeSet	O(log n) 排序
键值对	HashMap	O(1) 获取/存放

问题	原因	解决方案
NullPointerException	空引用	使用 Optional
ConcurrentModificationException	迭代时修改	Iterator.remove()
ClassCastException	类型错误	使用泛型

🇺🇸English

Java Fundamentals Skill

Master core Java programming with production-quality patterns.

Overview

This skill covers Java fundamentals including syntax, OOP, collections, streams API, and exception handling for Java 8-21.

When to Use This Skill

Use when you need to:

Write clean, idiomatic Java code
Design classes following OOP principles
Choose appropriate collection types
Implement functional programming patterns
Handle exceptions properly

Topics Covered

Core Syntax (Java 8-21)

Variables, data types, operators
Control flow, methods, classes
Records (Java 16+), sealed classes (Java 17+)
Pattern matching (Java 21)

Object-Oriented Programming

Classes, inheritance, polymorphism
Interfaces and abstract classes
SOLID principles

Collections Framework

List: ArrayList, LinkedList
Set: HashSet, TreeSet
Map: HashMap, ConcurrentHashMap
Queue: ArrayDeque, PriorityQueue

Streams API

filter, map, flatMap, reduce, collect
Optional handling
Parallel streams

Exception Handling

Checked vs unchecked exceptions
Try-with-resources
Custom exceptions

Quick Reference

// Record (Java 16+)
public record User(String name, String email) {}

// Pattern matching (Java 21)
String format(Object obj) {
    return switch (obj) {
        case Integer i -> "Int: %d".formatted(i);
        case String s -> "String: %s".formatted(s);
        default -> obj.toString();
    };
}

// Stream operations
List<String> names = users.stream()
    .filter(User::isActive)
    .map(User::getName)
    .sorted()
    .toList();

// Optional handling
String name = Optional.ofNullable(user)
    .map(User::getName)
    .orElse("Unknown");

Collection Selection

Need	Use	Reason
Indexed access	ArrayList	O(1) random access
Unique elements	HashSet	O(1) contains
Sorted unique	TreeSet	O(log n) sorted
Key-value pairs	HashMap	O(1) get/put

Troubleshooting

Problem	Cause	Solution
NullPointerException	Null reference	Use Optional
ConcurrentModificationException	Modify during iteration	Iterator.remove()
ClassCastException	Wrong type	Use generics

Usage

Skill("java-fundamentals")

Weekly Installs

229

Repository

pluginagentmark…gin-java

GitHub Stars

First Seen

Jan 21, 2026

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