大數(shù)據(jù) java 代碼示例

Java變量 (Java variables)

Variables are the user-defined names of the memory blocks, and their values can be changed at any time during program execution. They play an important role in a class/program as they help in to store, retrieve a data value.

變量是用戶定義的存儲(chǔ)塊名稱，它們的值可以在程序執(zhí)行期間隨時(shí)更改。 它們?cè)陬?程序中起著重要的作用，因?yàn)樗鼈冇兄诖鎯?chǔ)，檢索數(shù)據(jù)值。

Java中變量的類型 (Types of the variables in Java)

There are three types of Java variables,

Java變量有三種類型 ，

Instance Variables

實(shí)例變量

Local Variables

局部變量

Class/Static Variables

類/靜態(tài)變量

1)實(shí)例變量 (1) Instance Variables)

• Instance variables are declared in a class but outside a Method, Block or Constructor.

  實(shí)例變量在類中聲明，但在方法，塊或構(gòu)造函數(shù)之外。

• Instance variables have a default value 0.

  實(shí)例變量的默認(rèn)值為0 。

• These variables can be created only when the object of a class is created.

  僅當(dāng)創(chuàng)建類的對(duì)象時(shí)才能創(chuàng)建這些變量。

Example:

例：

public class Bike {public String color;Bike(String c) {color = c;}public void display() {System.out.println("color of the bike is " + color);}public static void main(String args[]) {Bike obj = new Bike("Red");obj.display();} }

Output

輸出量

Color of the bike is Red

2)局部變量 (2) Local Variables)

• Local variables are the variables which are declared in a class method.

  局部變量是在類方法中聲明的變量。

• We can use these variables within a block only.

  我們只能在一個(gè)塊中使用這些變量。

Example:

例：

public class TeacherDetails {public void TeacherAge() {int age = 0;age = age + 10;System.out.println("Teacher age is : " + age);}public static void main(String args[]) {TeacherDetails obj = new TeacherDetails();obj.TeacherAge();} }

Output

輸出量

Teacher age is : 10

3)類變量/靜態(tài)變量 (3) Class Variables/Static Variables)

• This can be called Both Class and Static Variable.

  這可以稱為類和靜態(tài)變量 。

• These variables have only one copy that is shared by all the different objects in a class.

  這些變量只有一個(gè)副本，該副本由類中的所有不同對(duì)象共享。

• It is created during the start of program execution and destroyed when the program ends.

  它在程序執(zhí)行開始時(shí)創(chuàng)建，并在程序結(jié)束時(shí)銷毀。

• Its Default value is 0.

  其默認(rèn)值為0 。

Example:

例：

public class Bike {public static int tyres;public static void main(String args[]) {tyres = 6;System.out.println("Number of tyres are " + tyres);} }

Output

輸出量

Number of tyres are 6

翻譯自: https://www.includehelp.com/java/variables-types-with-examples.aspx

大數(shù)據(jù) java 代碼示例

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