Application of Java function access modifiers in multi-threading

Application of access permission modifiers in multi-threading: public: can be accessed anywhere in the program, allowing threads to call functions. protected: Can be accessed in the same package and its subclasses to ensure encapsulation. default (package visible): can be accessed in the same package, providing certain access restrictions. Private: Access is limited to the class in which it is defined to prevent data race conditions.

Application of Java function access modifiers in multi-threading

Introduction

In a multi-threaded environment, access modifiers are critical to ensuring thread safety and program correctness. This article will delve into the access modifiers of Java functions and demonstrate their application in multi-threading through practical cases.

Access Modifiers

There are four access modifiers in Java:

• public: Code Accessible from anywhere in the program.
• protected: The code is accessible in the same package and its subclasses.
• default (also called package visible): The code is accessible within the same package.
• private: Code can only be accessed within the class in which it is defined.

The importance of access permission modifiers in multi-threading

In a multi-threaded environment, multiple threads may access shared data at the same time. If appropriate access modifiers are not used, thread safety issues may result, such as:

• Data race condition: Multiple threads modify shared data at the same time, resulting in unpredictability the result of.
• Visibility issue: Threads cannot see updates made to shared data by other threads.
• Ordered access problem: The order of thread access to shared data cannot be guaranteed.

Practical case

Consider the following bank account class, which contains three functions: deposit, withdraw and get balance:

public class BankAccount {

    private int balance;

    public void deposit(int amount) {
        balance += amount;
    }

    public void withdraw(int amount) {
        balance -= amount;
    }

    public int getBalance() {
        return balance;
    }
}

In In this example, the balance member variable is marked private. This means that access to it is limited to within the BankAccount class. This is done to avoid data race conditions since only a single thread can modify the balance.

On the other hand, the deposit(), withdraw() and getBalance() functions are marked public, Allows them to be called from anywhere. This is necessary because threads need access to these functions to manage accounts.

Other Considerations

In addition to access modifiers, there are also the following things to consider in a multi-threaded environment:

• Synchronization: Use locks or other synchronization mechanisms to control access to shared data.
• Atomicity: Ensure that the operation is atomic, that is, either the entire operation is executed successfully, or the entire operation is not executed.
• Visibility: Ensure that updates to shared data are visible to all threads by using the volatile keyword or MemoryBarrier.

Conclusion

Access modifiers play a vital role in multithreading, they help prevent thread safety issues and ensure program correctness sex. By carefully choosing access modifiers, you can create safe and reliable multi-threaded applications.

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