Can a Single Java File Hold Multiple Classes?

Can Java Files Contain Multiple Classes?

Java allows multiple classes to coexist within a single Java file. While this is not a common practice, understanding the concept can benefit programmers.

Why Include Multiple Classes in One Java File?

Including multiple classes in a single file serves the purpose of grouping related functionality together, such as:

• Internal data structures
• Support classes for the main class

Limitations on Multiple Classes

However, there are restrictions on multiple classes in a Java file:

• Only one public top-level class is permitted.
• Public top-level class names must match the Java source file name.

Achieving Multiple Classes (Non-Public Case)

It is possible to create non-public inner classes within a public top-level class. These inner classes can access private members of the enclosing class.

Example:

<code class="java">// File: Example.java
public class Example {
    private String name;
    
    class InnerClass {
        public String getName() {
            return name; // Can access private members of Example class
        }
    }
}</code>

Note: Inner classes are discussed separately and are not considered multiple top-level classes.

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