CS-Notes/notes/Java 基础语法.md

<!-- GFM-TOC -->
* [????](#????)
    * [ final](#-final)
    * [????????](#????????)
    * [???????](#???????)
* [????](#????)
    * [Set](#set)
    * [Queue](#queue)
    * [Map](#map)
* [????](#????)
* [??](#??)
* [?<3F><>?????](#?<3F><>?????)
<!-- GFM-TOC -->

# ????

##  final

**final ????**

??????????????????????????????????????????????????????????????????

????????????final ???????????????????final ????<3F><>?????????????????????????????????????????????

**final ????**

????????????????????

private ?????????????? final????????????<3F><>?????????????<3F><>???? private ????????????????????????????????????????????????

**final ??**

????????????<3F><>?

## ????????

static ??????????????????????????????????????????????????<3F><>??????????????????????

```java
public static String staticField = "???????";
```

static ????? static ???????????????????????????<3F><>?????????????????????????????<3F><>????

```java
static {
    System.out.println("??????????");
}
```

??????????????????????????????????????????????

```java
public String field = "????";
```

```java
{
    System.out.println("???????");
}
```

????????????<3F><>???????<3F><>????

```java
public InitialOrderTest()
{
    System.out.println("??????");
}
```

?????<3F><>??????????????????

1. ??????????????????<3F><>
2. ??????????????????<3F><>
3. ????????????<3F><>
4. ????????????
5. ????????????<3F><>
6. ????????????

## ???????

Java ??????????????????<3F><>???private??protected ??? public???????????????<3F><>???????????????

???????????<3F><>???????????????????????????<3F><>??????????????????????<3F><>?????????????????<3F><>????????????????????????????????????????????<3F><>??????????????????????????????????

protected ???????<3F><>???????????????<3F><>????????????????????????????<3F><>?????????????<3F><>???????<3F><>???????

# ????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/114c49a6-72e3-4264-ae07-c564127094ac.png)

??????????? Collection ?? Map ?????Collection ??????? List??Set ??? Queue??

## Set

- HashSet????? Hash ???????????????????????????

- TreeSet?????????????????????????<3F><>????? HashSet??

- LinkedListHashSet?????? HashSet ?????<3F><>?????????????????????????????????????????

## Queue

???????????LinkedList ?? PriorityQueue?????? LinkedList ????????<3F><>?

## Map

- HashMap????? Hash ???

- LinkedHashMap???????????????????????????????????LRU?????

- TreeMap?????????????

- ConcurrentHashMap??????? Map?????<3F>p???????

# ????

?????????? **Class** ??????????????<3F><>???????????????????????????????????? .class ??????????????????? Class ????

????????? Class ?????????????????????????????? JVM ?<3F><>???????? Class.forName('com.mysql.jdbc.Driver.class') ????????????????????<3F><>?????????? Class ????

???????????????????????????????????????????????????????????????????? .class ???????????????????

Class ?? java.lang.reflect ???????????????java.lang.reflect ???????? **Field**??**Method** ??? **Constructor** ????????? get() ?? set() ???????????? Field ???????????<3F><>???????? invoke() ?????????? Method ???????????????????? Constructor ??????????

IDE ??<3F><>???????????????????????????????????????????<3F><>??????????????????<3F><>???????????

# ??

Throwable ????????????<3F>ʦ<EFBFBD>???????????????????????**Error** ?? **Exception**?????? Error ??????????????????

Exception ????????**?????** ?? **???????**???????????? try...catch... ???????<3F><>??????????????<3F><>?????????????????????????????? 0 ?????? Arithmetic Exception???????????????????????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/48f8f98e-8dfd-450d-8b5b-df4688f0d377.jpg)

# ?<3F><>?????

- Eckel B, ????? , ??? , ?? . Java ?????? [M]. ??<3F><>????????? , 2002.
- [Java ????????? ](https://segmentfault.com/a/1190000004527951)