86 lines
1.3 KiB
Markdown
86 lines
1.3 KiB
Markdown
# Java 学习笔记
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## 基础语法
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### 变量和数据类型
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```java
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// 基本数据类型
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int age = 25;
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double price = 99.99;
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boolean isActive = true;
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String name = "Java";
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```
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### 控制结构
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```java
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// if-else
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if (age >= 18) {
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System.out.println("成年人");
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} else {
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System.out.println("未成年人");
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}
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// for 循环
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for (int i = 0; i < 10; i++) {
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System.out.println(i);
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}
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```
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## 面向对象
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### 类和对象
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```java
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public class Person {
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private String name;
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private int age;
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public Person(String name, int age) {
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this.name = name;
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this.age = age;
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}
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public void introduce() {
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System.out.println("我是 " + name + "，今年 " + age + " 岁");
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}
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}
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```
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## 集合框架
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### List
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```java
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List<String> list = new ArrayList<>();
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list.add("Java");
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list.add("Python");
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list.add("Go");
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```
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### Map
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```java
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Map<String, Integer> map = new HashMap<>();
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map.put("Java", 1);
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map.put("Python", 2);
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```
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## 常用工具类
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### String 操作
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```java
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String str = "Hello World";
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str.length(); // 长度
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str.substring(0, 5); // 子串
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str.split(" "); // 分割
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```
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## 学习资源
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- [Oracle Java 教程](https://docs.oracle.com/javase/tutorial/)
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- [Java 官方文档](https://docs.oracle.com/en/java/)
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