How to use default in java

The default keyword in Java is used to modify variables, methods and classes, indicating default access permissions, that is, it can only be accessed in the same package or in the class or subclass to which the element belongs.

Usage of default keyword in Java

What is default

## The #default keyword is used in Java to modify variables, methods, and classes. It represents default access, which means that the element will have that access if no other access is explicitly specified.

Variable usage

Member variables that do not explicitly specify access permissions default to default access permissions. This means that the variable can only be accessed within the same package or within the class or subclass to which the variable belongs.

<code class="java">class MyClass {
    int defaultVariable;
}</code>

Method Usage

Methods that do not explicitly specify access permissions also default to default access permissions. This means that the method can only be called within the same package or within the class or subclass to which the method belongs.

<code class="java">class MyClass {
    void defaultMethod() {
        // 方法体
    }
}</code>

Class Usage

If access permissions are not explicitly specified, the class will also default to default access permissions. This means that the class can only be accessed within the same package.

<code class="java">package com.example;

class DefaultClass {
    // 类体
}</code>

Usage scenarios

default access rights are usually used for elements that only want to be accessible within the same package. For example, utility methods, inner classes, or constants used only within a specific package.

Note

Default access is more restrictive than protected access and does not allow subclasses to access elements in other packages.

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