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JAVA 数据类型


Java 数据类型

正如前一章所解释的,多变的在Java中必须是指定的数据类型:

示例

int myNum = 5;               // Integer (whole number)
float myFloatNum = 5.99f;    // Floating point number
char myLetter = 'D';         // Character
boolean myBool = true;       // Boolean
String myText = "Hello";     // String

亲自试一试 »

数据类型分为两组:

  • 原始数据类型 - 包括byte,short,int,long,float,double,booleanchar
  • 非原始数据类型 - 例如String,数组课程(您将在后面的章节中了解更多相关内容)

原始数据类型

原始数据类型指定变量值的大小和类型,并且没有附加方法。

Java中有八种基本数据类型:

Data Type Size Description
byte 1 byte Stores whole numbers from -128 to 127
short 2 bytes Stores whole numbers from -32,768 to 32,767
int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647
long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits
double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits
boolean 1 bit Stores true or false values
char 2 bytes Stores a single character/letter or ASCII values

通过练习测试一下

练习:

为以下变量添加正确的数据类型:

 myNum = 9;
 myFloatNum = 8.99f;
 myLetter = 'A';
 myBool = false;
 myText = "Hello World";

开始练习