CS-Notes/notes/Java 基础语法.md

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

# ????

##  final

**final ????**

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

????????????final ???????????????????final ???????????????????????????????????????????????????

**final ????**

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

private ?????????????? final????????????????????????????????? private ????????????????????????????????????????????????

**final ??**

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

## ????????

static ??????????????????????????????????????????????????????????????????????????

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

static ????? static ????????????????????????????????????????????????????????????????

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

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

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

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

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

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

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

1. ???????????????????
2. ???????????????????
3. ?????????????
4. ????????????
5. ?????????????
6. ????????????

## ???????

Java ???????????????????????private??protected ??? public????????????????????????????????

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

protected ???????????????????????????????????????????????????????????????????????????????????????

# ????

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

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

## Set

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

- TreeSet???????????????????????????????? HashSet??

- LinkedListHashSet?????? HashSet ????????????????????????????????????????????????

## Queue

???????????LinkedList ?? PriorityQueue?????? LinkedList ???????????

## Map

- HashMap????? Hash ???

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

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

- ConcurrentHashMap??????? Map??????p???????

# ????

?????????? **Class** ???????????????????????????????????????????????????? .class ??????????????????? Class ????

????????? Class ?????????????????????????????? JVM ??????????? Class.forName('com.mysql.jdbc.Driver.class') ???????????????????????????????? Class ????

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

Class ?? java.lang.reflect ???????????????java.lang.reflect ???????? **Field**??**Method** ??? **Constructor** ????????? get() ?? set() ???????????? Field ????????????????????? invoke() ?????????? Method ???????????????????? Constructor ??????????

IDE ????????????????????????????????????????????????????????????????????????????????

# ??

Throwable ??????????????????????????????????????**Error** ?? **Exception**?????? Error ??????????????????

Exception ????????**?????** ?? **???????**???????????? try...catch... ??????????????????????????????????????????????????????? 0 ?????? Arithmetic Exception???????????????????????

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

# ????????

- Eckel B, ????? , ??? , ?? . Java ?????? [M]. ????????????? , 2002.
- [Java ????????? ](https://segmentfault.com/a/1190000004527951)
auto commit 2018-02-20 10:40:05 +08:00			`<!-- GFM-TOC -->`
auto commit 2018-02-22 22:54:49 +08:00			`* [????](#????)`
auto commit 2018-02-20 10:40:05 +08:00			`* [ final](#-final)`
auto commit 2018-02-22 22:54:49 +08:00			`* [????????](#????????)`
			`* [???????](#???????)`
			`* [????](#????)`
auto commit 2018-02-20 10:40:05 +08:00			`* [Set](#set)`
			`* [Queue](#queue)`
			`* [Map](#map)`
auto commit 2018-02-22 22:54:49 +08:00			`* [????](#????)`
			`* [??](#??)`
auto commit 2018-02-23 18:10:07 +08:00			`* [????????](#????????)`
auto commit 2018-02-20 10:40:05 +08:00			`<!-- GFM-TOC -->`

auto commit 2018-02-22 22:54:49 +08:00			`# ????`
auto commit 2018-02-20 10:40:05 +08:00
			`## final`

auto commit 2018-02-22 22:54:49 +08:00			`final ????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`??????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`????????????final ???????????????????final ???????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`final ????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`private ?????????????? final????????????????????????????????? private ????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`final ??`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`???????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`## ????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`static ??????????????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			```java
auto commit 2018-02-22 22:54:49 +08:00			`public static String staticField = "???????";`
auto commit 2018-02-20 10:40:05 +08:00			```

auto commit 2018-02-23 18:10:07 +08:00			`static ????? static ????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			```java
			`static {`
auto commit 2018-02-22 22:54:49 +08:00			`System.out.println("??????????");`
auto commit 2018-02-20 10:40:05 +08:00			`}`
			```

auto commit 2018-02-22 22:54:49 +08:00			`??????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			```java
auto commit 2018-02-22 22:54:49 +08:00			`public String field = "????";`
auto commit 2018-02-20 10:40:05 +08:00			```

			```java
			`{`
auto commit 2018-02-22 22:54:49 +08:00			`System.out.println("???????");`
auto commit 2018-02-20 10:40:05 +08:00			`}`
			```

auto commit 2018-02-23 18:10:07 +08:00			`???????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			```java
			`public InitialOrderTest()`
			`{`
auto commit 2018-02-22 22:54:49 +08:00			`System.out.println("??????");`
auto commit 2018-02-20 10:40:05 +08:00			`}`
			```

auto commit 2018-02-23 18:10:07 +08:00			`?????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`1. ???????????????????`
			`2. ???????????????????`
			`3. ?????????????`
auto commit 2018-02-22 22:54:49 +08:00			`4. ????????????`
auto commit 2018-02-23 18:10:07 +08:00			`5. ?????????????`
auto commit 2018-02-22 22:54:49 +08:00			`6. ????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`## ???????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`Java ???????????????????????private??protected ??? public????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`protected ???????????????????????????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`# ????`
auto commit 2018-02-20 10:40:05 +08:00
			`![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/114c49a6-72e3-4264-ae07-c564127094ac.png)`

auto commit 2018-02-22 22:54:49 +08:00			`??????????? Collection ?? Map ?????Collection ??????? List??Set ??? Queue??`
auto commit 2018-02-20 10:40:05 +08:00
			`## Set`

auto commit 2018-02-22 22:54:49 +08:00			`- HashSet????? Hash ???????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`- TreeSet???????????????????????????????? HashSet??`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`- LinkedListHashSet?????? HashSet ????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			`## Queue`

auto commit 2018-02-23 18:10:07 +08:00			`???????????LinkedList ?? PriorityQueue?????? LinkedList ???????????`
auto commit 2018-02-20 10:40:05 +08:00
			`## Map`

auto commit 2018-02-22 22:54:49 +08:00			`- HashMap????? Hash ???`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`- LinkedHashMap???????????????????????????????????LRU?????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`- TreeMap?????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`- ConcurrentHashMap??????? Map??????p???????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`# ????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`?????????? Class ???????????????????????????????????????????????????? .class ??????????????????? Class ????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`????????? Class ?????????????????????????????? JVM ??????????? Class.forName('com.mysql.jdbc.Driver.class') ???????????????????????????????? Class ????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`???????????????????????????????????????????????????????????????????? .class ???????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`Class ?? java.lang.reflect ???????????????java.lang.reflect ???????? Field??Method ??? Constructor ????????? get() ?? set() ???????????? Field ????????????????????? invoke() ?????????? Method ???????????????????? Constructor ??????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`IDE ????????????????????????????????????????????????????????????????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-22 22:54:49 +08:00			`# ??`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`Throwable ??????????????????????????????????????Error ?? Exception?????? Error ??????????????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`Exception ????????????? ?? ??????????????????? try...catch... ??????????????????????????????????????????????????????? 0 ?????? Arithmetic Exception???????????????????????`
auto commit 2018-02-20 10:40:05 +08:00
			`![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/48f8f98e-8dfd-450d-8b5b-df4688f0d377.jpg)`

auto commit 2018-02-23 18:10:07 +08:00			`# ????????`
auto commit 2018-02-20 10:40:05 +08:00
auto commit 2018-02-23 18:10:07 +08:00			`- Eckel B, ????? , ??? , ?? . Java ?????? [M]. ????????????? , 2002.`
auto commit 2018-02-22 22:54:49 +08:00			`- [Java ????????? ](https://segmentfault.com/a/1190000004527951)`