实例变量和局部变量的区别

变量是赋予内存位置的名称。它是程序中存储的基本单位。

• 存储在变量中的值可以在程序执行期间更改。
• 变量只是一个内存位置的名称。所有操作都是在内存位置的可变效果上完成的。
• 在Java，所有变量必须在使用前声明。

实例变量：这些变量在类内声明，但在方法、构造函数或块之外，并且始终获得默认值。

• 这些变量通常在我们创建对象时创建，并在对象销毁时销毁。
• 我们可以使用访问说明符，例如变量，如果没有指定访问说明符，则使用默认访问说明符。
• 每个对象都有自己的实例变量副本。

例子：

class Taxes  
{  
   int count; // Count is an Instance variable  
   /*...*/  
}  

局部变量：这些变量在方法中声明，但没有任何默认值。

• 它们通常在我们进入方法或构造函数时创建，并在退出块或从方法调用返回时销毁。
• 它的范围通常限于一个方法，它的范围从它们声明的那一行开始。它们的作用域通常保持在那里，直到方法的右花括号出现。
• 局部变量的初始化是强制性的。

例子：

int area()      
{    
        int length = 10; // Local variable          
        int breadth = 5; // Local variable          
        int rectarea = length*breadth; // Local variable          
        return rectarea;          
}  

实例变量与局部变量之间的表格差异：

Instance Variable	Local Variable
They are defined in class but outside the body of methods.	They are defined as a type of variable declared within programming blocks or subroutines.
These variables are created when an object is instantiated and are accessible to all constructors, methods, or blocks in class.	These variables are created when a block, method or constructor is started and the variable will be destroyed once it exits the block, method, or constructor.
These variables are destroyed when the object is destroyed.	These variables are destroyed when the constructor or method is exited.
It can be accessed throughout the class.	Its access is limited to the method in which it is declared.
They are used to reserving memory for data that the class needs and that too for the lifetime of the object.	They are used to decreasing dependencies between components I.e., the complexity of code is decreased.
These variables are given a default value if it is not assigned by code.	These variables do not always have some value, so there must be a value assigned by code.
It is not compulsory to initialize instance variables before use.	It is important to initialize local variables before use.
It includes access modifiers such as private, public, protected, etc.	It does not include any access modifiers such as private, public, protected, etc.