Java學(xué)習(xí)筆記：從入門到實(shí)戰(zhàn)

第1 章　Java 語(yǔ)言基礎(chǔ)
1.1　Java 語(yǔ)言介紹 ....................................................................................................1
1.1.1　Java 語(yǔ)言的發(fā)展歷程 .........................................................................................1
1.1.2　Java 語(yǔ)言的體系 .................................................................................................2
1.1.3　Java 語(yǔ)言的特點(diǎn) .................................................................................................2
1.1.4　Java 語(yǔ)言的地位 .................................................................................................3
1.2　搭建Java 開(kāi)發(fā)環(huán)境 ...........................................................................................3
1.2.1　安裝JDK .............................................................................................................3
1.2.2　在Windows 7 配置Java 環(huán)境 ............................................................................6
1.2.3　在Windows 10 配置Java 環(huán)境 ..........................................................................6
1.2.4　充分利用Java API 文檔 .....................................................................................8
1.3　個(gè)Java 程序 ...............................................................................................9
1.3.1　編寫個(gè)Java 代碼 ........................................................................................9
實(shí)例1-1：個(gè)Java 程序代碼 ................................................................................................ 9
1.3.2　編譯Java 程序 ....................................................................................................9
1.3.3　運(yùn)行Java 代碼 ..................................................................................................10
1.3.4　Java 11 新特性：新的程序運(yùn)行方式 .............................................................11
第２章　使用IDE 開(kāi)發(fā)工具
2.1　使用Eclipse .....................................................................................................12
2.1.1　IDE 介紹 ...........................................................................................................12
2.1.2　下載并安裝Eclipse ..........................................................................................12
2.1.3　新建一個(gè)Eclipse 項(xiàng)目 .....................................................................................16
2.1.4　編譯并運(yùn)行Eclipse 項(xiàng)目 .................................................................................17
2.1.5　使用Eclipse 打開(kāi)一個(gè)Java 工程——打開(kāi)下載包中的項(xiàng)目 ........................18
2.2　使用Intellij IDEA ............................................................................................19
2.2.1　搭建IntelliJ IDEA 開(kāi)發(fā)環(huán)境 ...........................................................................19
2.2.2　使用IntelliJ IDEA 新建Java 工程 ..................................................................21
2.2.3　使用IntelliJ IDEA 運(yùn)行Java 程序 ..................................................................22
第3 章　Java 基礎(chǔ)語(yǔ)法
3.1　關(guān)鍵字、標(biāo)識(shí)符和注釋 ..................................................................................23
3.1.1　關(guān)鍵字 ...............................................................................................................23
3.1.2　標(biāo)識(shí)符 ...............................................................................................................24
3.1.3　注釋 ...................................................................................................................24
3.2　變量和常量 ......................................................................................................25
3.2.1　常量 ...................................................................................................................25
實(shí)例3-1：定義幾個(gè)Java 常量 .................................................................................................. 25
3.2.2　變量 ...................................................................................................................26
實(shí)例3-2：計(jì)算三角形、正方形和長(zhǎng)方形的面積 ................................................................... 27
實(shí)例3-3：輸出各種變量的值 ................................................................................................... 27
3.3　數(shù)據(jù)類型 ..........................................................................................................28
3.3.1　為什么引入數(shù)據(jù)類型 .......................................................................................29
3.3.2　基本數(shù)據(jù)類型的取值范圍 ...............................................................................29
3.3.3　字符型 ...............................................................................................................30
實(shí)例3-4：輸出三種特殊符號(hào) ................................................................................................... 30
3.3.4　整型 ...................................................................................................................31
實(shí)例3-5：通過(guò)整型類型計(jì)算圖形周長(zhǎng)和面積 ....................................................................... 31
3.3.5　浮點(diǎn)型 ...............................................................................................................32
實(shí)例3-6：計(jì)算圓的面積 ........................................................................................................... 33
3.3.6　布爾型 ...............................................................................................................33
實(shí)例3-7：比較兩個(gè)數(shù)的大小 ................................................................................................... 33
3.4　運(yùn)算符 ..............................................................................................................34
3.4.1　算術(shù)運(yùn)算符 .......................................................................................................34
實(shí)例3-8：基本的數(shù)學(xué)運(yùn)算（加、減、乘、除） ................................................................... 34
實(shí)例3-9：使用“%”運(yùn)算符 .................................................................................................... 35
實(shí)例3-10：使用遞增與遞減運(yùn)算符 ......................................................................................... 36
3.4.2　關(guān)系運(yùn)算符和邏輯運(yùn)算符 ...............................................................................36
實(shí)例3-11：使用關(guān)系運(yùn)算符比較數(shù)字和字符 ......................................................................... 37
3.4.3　位運(yùn)算符 ...........................................................................................................38
實(shí)例3-12：對(duì)兩個(gè)整數(shù)實(shí)現(xiàn)位運(yùn)算 ......................................................................................... 39
3.4.4　條件運(yùn)算符 .......................................................................................................39
實(shí)例3-13：使用條件運(yùn)算符判斷成績(jī)是否優(yōu)秀 ..................................................................... 39
3.4.5　賦值運(yùn)算符 .......................................................................................................40
實(shí)例3-14：賦值類型不匹配的錯(cuò)誤 ......................................................................................... 40
3.4.6　運(yùn)算符的優(yōu)先級(jí) ...............................................................................................40
實(shí)例3-15：四則混合運(yùn)算 ......................................................................................................... 41
3.5　類型轉(zhuǎn)換 ..........................................................................................................42
3.5.1　自動(dòng)類型轉(zhuǎn)換 ...................................................................................................42
實(shí)例3-16：將整數(shù)自動(dòng)轉(zhuǎn)換為fl oat 類型 ................................................................................ 42
3.5.2　強(qiáng)制轉(zhuǎn)換 ...........................................................................................................43
實(shí)例3-17：實(shí)現(xiàn)int、byte 和double 類型之間的強(qiáng)制轉(zhuǎn)換 ................................................... 43
第4 章　使用條件語(yǔ)句
4.1　使用if 語(yǔ)句 ......................................................................................................44
4.1.1　if 語(yǔ)句介紹 ........................................................................................................44
實(shí)例4-1：判斷成績(jī)是否及格 ................................................................................................... 45
4.1.2　if 語(yǔ)句的延伸 ....................................................................................................45
實(shí)例4-2：對(duì)兩種條件給出不同的答案 ................................................................................... 46
4.1.3　多個(gè)條件判斷的if 語(yǔ)句 ...................................................................................46
實(shí)例4-3：模擬抽獎(jiǎng)系統(tǒng) ........................................................................................................... 47
4.2　使用switch 語(yǔ)句 ..............................................................................................47
4.2.1　switch 語(yǔ)句基礎(chǔ) ................................................................................................48
實(shí)例4-4：判斷數(shù)字的大小 ....................................................................................................... 48
4.2.2　沒(méi)有break 時(shí)的情形 ........................................................................................49
實(shí)例4-5：執(zhí)行switch 后面的所有分支條件語(yǔ)句 ................................................................... 49
4.2.3　case 沒(méi)有執(zhí)行語(yǔ)句 ...........................................................................................49
實(shí)例4-6：在case 語(yǔ)句后沒(méi)有執(zhí)行的代碼 .............................................................................. 50
4.2.4　default 可以不在末尾 .......................................................................................50
實(shí)例4-7：將default 放在個(gè)case 分支中 ......................................................................... 50
第5 章　使用循環(huán)語(yǔ)句
5.1　使用for 循環(huán)語(yǔ)句 ............................................................................................51
5.1.1　for 循環(huán)介紹 .....................................................................................................51
實(shí)例5-1：輸出整數(shù)0 到9 ........................................................................................................ 52
5.1.2　嵌套使用for 循環(huán) ............................................................................................52
實(shí)例5-2：使用嵌套for 語(yǔ)句顯示人民幣符號(hào)和美元符號(hào) ..................................................... 53
實(shí)例5-3：在屏幕中輸出一個(gè)用“*”擺放的菱形 ................................................................. 53
5.2　使用while 循環(huán)語(yǔ)句 .......................................................................................54
5.2.1　while 循環(huán)基礎(chǔ) .................................................................................................54
實(shí)例5-4：循環(huán)輸出18 個(gè)數(shù)字 ................................................................................................. 54
實(shí)例5-5：輸出能夠整除7 的數(shù)字 ........................................................................................... 55
5.2.2　do-while 循環(huán)語(yǔ)句 ............................................................................................55
實(shí)例5-6：使用do-while 語(yǔ)句輸出0 到7 ................................................................................ 56
實(shí)例5-7：計(jì)算1 2 3 …. 100 的和 ....................................................................................... 56
5.3　使用跳轉(zhuǎn)語(yǔ)句 ..................................................................................................57
5.3.1　break 語(yǔ)句 .........................................................................................................57
實(shí)例5-8：使用break 終止循環(huán)的執(zhí)行 .................................................................................... 57
實(shí)例5-9：在while 循環(huán)語(yǔ)句中使用break............................................................................... 57
實(shí)例5-10：使用有標(biāo)號(hào)的break 語(yǔ)句 ...................................................................................... 58
5.3.2　使用return 語(yǔ)句 ...............................................................................................59
實(shí)例5-11：使用return 語(yǔ)句結(jié)束循環(huán)的執(zhí)行 .......................................................................... 59
5.3.3　使用continue 跳轉(zhuǎn)語(yǔ)句 ...................................................................................59
實(shí)例5-12：使用continue 改變for 循環(huán)的運(yùn)行結(jié)果 ............................................................... 59
第6 章　操作字符串
6.1　Java 字符串的初始化 ......................................................................................61
實(shí)例6-1：實(shí)現(xiàn)Java 字符串的初始化 ...................................................................................... 61
6.2　使用String 類操作字符串 ..............................................................................62
6.2.1　獲取指定索引位置的字符 ...............................................................................62
實(shí)例6-2：返回某個(gè)字符串指定索引的字符 ........................................................................... 62
6.2.2　追加字符串 .......................................................................................................63
實(shí)例6-3：在字符串后面追加字符串（好好 學(xué)習(xí)） ........................................................... 63
6.2.3　連接多個(gè)字符串 ...............................................................................................63
實(shí)例6-4：使用“ ”連接兩個(gè)對(duì)象 ......................................................................................... 63
6.2.4　比較字符串 .......................................................................................................63
實(shí)例6-5：判斷兩個(gè)指定的字符串是否相等 ........................................................................... 64
6.2.5　獲得字符串長(zhǎng)度 ...............................................................................................64
實(shí)例6-6：獲取字符串的長(zhǎng)度 ................................................................................................... 64
6.2.6　替換字符串 .......................................................................................................65
實(shí)例6-7：替換字符串中的某一個(gè)文字 ................................................................................... 65
6.2.7　截取字符串 .......................................................................................................65
實(shí)例6-8：截取一個(gè)字符串，并輸出截取后的結(jié)果 ............................................................... 65
6.2.8　字符串的大小寫互轉(zhuǎn) .......................................................................................66
實(shí)例6-9：對(duì)指定的字符串實(shí)現(xiàn)大小寫轉(zhuǎn)換 ........................................................................... 66
6.2.9　消除字符串中的空白字符 ...............................................................................66
實(shí)例6-10：去掉字符串開(kāi)頭的空白字符 ................................................................................. 66
6.2.10　查找字符串 .....................................................................................................67
實(shí)例6-11：查找字符串str 中空字符的位置 ........................................................................... 68
6.3　使用類StringBuffer ........................................................................................68
實(shí)例6-12：使用追加字符函數(shù) ................................................................................................. 69
第7 章　使用數(shù)組
7.1　簡(jiǎn)單的一維數(shù)組 ..........................................................................................70
7.1.1　聲明一維數(shù)組 ...................................................................................................70
7.1.2　創(chuàng)建一維數(shù)組 ...................................................................................................70
實(shí)例7-1：創(chuàng)建并輸出一維數(shù)組中的數(shù)據(jù) ............................................................................... 71
7.1.3　初始化一維數(shù)組 ...............................................................................................72
實(shí)例7-2：初始化一維數(shù)組，并將數(shù)組值輸出打印 ............................................................... 72
7.2　二維數(shù)組 ..........................................................................................................73
7.2.1　聲明二維數(shù)組 ...................................................................................................73
7.2.2　創(chuàng)建二維數(shù)組 ...................................................................................................73
實(shí)例7-3：創(chuàng)建二維數(shù)組并輸出打印里面的數(shù)據(jù) ................................................................... 74
7.2.3　初始化二維數(shù)組 ...............................................................................................74
實(shí)例7-4：打印輸出二維數(shù)組中的數(shù)據(jù) ................................................................................... 75
7.3　三維數(shù)組 ..........................................................................................................76
7.3.1　聲明三維數(shù)組 ...................................................................................................76
7.3.2　初始化三維數(shù)組 ...............................................................................................76
實(shí)例7-5：創(chuàng)建三維數(shù)組，然后輸出打印數(shù)組內(nèi)元素 ........................................................... 77
7.4　操作數(shù)組 ..........................................................................................................77
7.4.1　復(fù)制數(shù)組 ...........................................................................................................78
實(shí)例7-6：復(fù)制一維數(shù)組中的元素 ........................................................................................... 78
7.4.2　比較數(shù)組 ...........................................................................................................79
實(shí)例7-7：比較兩個(gè)一維數(shù)組 ................................................................................................... 79
7.4.3　搜索數(shù)組中的元素 ...........................................................................................79
實(shí)例7-8：使用binarySearch() 搜索數(shù)組內(nèi)元素...................................................................... 79
7.4.4　排序數(shù)組 ...........................................................................................................80
實(shí)例7-9：使用sort() 排序數(shù)組內(nèi)元素 ..................................................................................... 80
7.4.5　填充數(shù)組 ...........................................................................................................80
實(shí)例7-10：使用fi ll() 向數(shù)組中添加新的元素 ........................................................................ 80
7.5　數(shù)組的高級(jí)用法 ..............................................................................................81
7.5.1　動(dòng)態(tài)數(shù)組 ...........................................................................................................81
實(shí)例7-11：將ArrayList 作為Java 動(dòng)態(tài)數(shù)組 ........................................................................... 82
7.5.2　使用foreach 循環(huán) .............................................................................................82
實(shí)例7-12：使用foreach 遍歷輸出數(shù)組中的元素 ................................................................... 83
7.5.3　數(shù)組和內(nèi)存 .......................................................................................................83
實(shí)例7-13：初始化基本類型數(shù)組 ............................................................................................. 84