（17）基本數據類型 · Java編程那些事

## Java編程那些事兒17——基本數據類型作者：陳躍峰出自：[http://blog.csdn.net/mailbomb](http://blog.csdn.net/mailbomb) **3.5 基本數據類型** 程序中最核心的就是一系列的數據，或者叫程序狀態，計算機為了方便的管理數據，就為數據設定了一組類型，這樣在為數據分配內存以及操作數據時都比較方便，這就是數據類型的由來。其實現實生活中也存在各種數據類型，例如數字型，字符型等，數字型又可以劃分為整數型和小數型，只是沒有很可以的劃分罷了。在數據類型中，最常用也是最基礎的數據類型，被稱作基本數據類型。可以使用這些類型的值來代表一些簡單的狀態。 **3.5.1 概述** 學習數據類型的目的就是在需要代表一個數值時，能夠選擇合適的類型。當然，有些時候好幾種類型都適合，那就要看個人習慣了。學習數據類型需要掌握每種數據類型的特征，以及對應的細節知識，這樣會有助于對類型的選擇。所以在初次學習時，需要記憶很多的內容 Java語言的基本數據類型總共有以下8種，下面是按照用途劃分出的4個類別： 1.?整數型：byte(字節型)、short(短整型)、int(整型)、long(長整型) 2.?小數型：float(單精度浮點型)、double(雙精度浮點型) 3.?字符型 4.?布爾型 **3.5.2?整數型** 整數型是一類代表整數值的類型。當需要代表一個整數的值時，可以根據需要從4種類型中挑選合適的，如果沒有特殊要求的話，一般選擇int類型。4種整數型區別主要在每個數據在內存中占用的空間大小和代表的數值的范圍。具體說明參看下表：? 整數型參數表 <table style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN-LEFT: 40.85pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse" cellspacing="0" cellpadding="0" border="1"><tbody><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">類型名稱</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">關鍵字</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">占用空間(字節)</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">取值范圍</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">默認值</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">字節型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">byte</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">-2<sup>7</sup>—2<sup>7</sup>-1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">0</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">短整型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">short</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">2</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">-2<sup>15</sup>—2<sup>15</sup>-1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">0</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">整型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">int</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">4</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">-2<sup>31</sup>—2<sup>31</sup>-1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">0</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">長整型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">long</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">8</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 63.8pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="85"> <div align="center">-2<sup>63</sup>—2<sup>63</sup>-1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 49.6pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="66"> <div align="center">0</div> </td> </tr></tbody></table> 說明：1、Java中的整數都是有符號數，也就是有正有負。 2、默認值指在特定的情況下才自動初始化，具體的情況后續將有敘述。 3、程序中的整數數值默認是int以及int以下類型，如果需要書寫long型的值，則需要在數值后面添加字母L，大小寫均可。 4、程序中默認整數是十進制數字，八進制數字以數字字符0開頭，例如016、034等，十六進制數字以數字字符0和字母x(不區分大小寫)開頭，例如0xaf、0X12等。 **3.5.3?小數型** 小數型是一類代表小數值的類型。當需要代表一個小數的值時，可以根據需要從以下2種類型中挑選合適的。如果沒有特殊要求，一般選擇double類型。由于小數的存儲方式和整數不同，所以小數都有一定的精度，所以在計算機中運算時不夠精確。根據精度和存儲區間的不同，設計了兩種小數類型，具體見下表：小數型參數表 <table style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN-LEFT: 26.7pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse" cellspacing="0" cellpadding="0" border="1"><tbody><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">類型名稱</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">關鍵字</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">占用空間(字節)</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">取值范圍</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">默認值</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">單精度浮點型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">float</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">4</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">-3.4E+38—3.4E+38</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">0.0f</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">雙精度浮點型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">double</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">8</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">-1.7E+308—1.7E+308</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">0.0</div> </td> </tr></tbody></table> 說明：1、取值范圍以科學計數法形式進行描述。 2、在程序中，小數的運算速度要低于整數運算。 3、float類型的小數，需要在小數后加字母f，不區分大小寫，例如1.01f。 **3.5.4?字符型** 字符型代表特定的某個字符，按照前面介紹的知識，計算機中都是以字符集的形式來保存字符的，所以字符型的值實際只是字符集中的編號，而不是實際代表的字符，由計算機完成從編號轉換成對應字符的工作。 Java語言中為了更加方便國際化，使用Unicode字符集作為默認的字符集，該字符集包含各種語言中常見的字符。在程序代碼中，字符使用一對單引號加上需要表達的字符來標識，例如’A’、’a’等，當然也可以直接使用字符編碼，也就是一個非負整數進行表示。字符型參數表 <table style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN-LEFT: 26.7pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse" cellspacing="0" cellpadding="0" border="1"><tbody><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">類型名稱</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">關鍵字</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">占用空間(字節)</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">取值范圍</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">默認值</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">字符型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">char</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">2</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">0-2<sup>16</sup>-1</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">0</div> </td> </tr></tbody></table> 說明：1、字符型的編號中不包含負數。 2、字符型由于存儲的是編號的數值，所以可以參與數學運算。 3、字符型可以作為Java語言中的無符號整數使用。 4、字符型的默認值是編號為0的字符，而不是字符0 **3.5.5?布爾型** 布爾型代表邏輯中的成立和不成立。Java語言中使用關鍵字true代表成立，false代表不成立。布爾型是存儲邏輯值的類型，其實很多程序中都有邏輯值的概念，Java把邏輯的值用布爾型來進行表達。布爾型參數表 <table style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN-LEFT: 26.7pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse" cellspacing="0" cellpadding="0" border="1"><tbody><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">類型名稱</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">關鍵字</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">占用空間(字節)</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">取值范圍</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: black 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">默認值</div> </td> </tr><tr><td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: black 1pt solid; WIDTH: 77.95pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="104"> <div align="center">布爾型</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">boolean</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 3cm; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="113"> <div align="center">?</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 106.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="142"> <div align="center">true或false</div> </td> <td style="BORDER-RIGHT: black 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 42.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: black 1pt solid" valign="top" width="57"> <div align="center">false</div> </td> </tr></tbody></table> 說明： 1、布爾型占用的空間取決于Java虛擬機(JVM)的實現，可能是1位也可能是1個字節。 **3.5.6?小結** 這里簡單的介紹了8種基本數據類型的基本特征，在實際的程序設計中，可以根據需要選擇對應的類型。由于Java語言是一種強類型的語言，所以在使用數據類型是需要小心。