When and Why Use `new String(...)` in Java?

Understanding the Purpose of "new String(...)" Syntax in Java

In Java, the "new String(...)" syntax is commonly encountered when assigning a String constant to a String object. This syntax differs from the typical method of assigning String constants directly, such as "s = "Hello World";". However, the purpose and effect of using the "new String(...)" syntax may not be immediately apparent.

Potential Reasons for Using "new String(...)"

One possible reason for using the "new String(...)" syntax is to create a distinct copy of an existing String object. This can be useful in scenarios where you want to prevent changes made to one String object from affecting another.

Implementation-Dependent Behavior

It's important to note that the behavior of "new String(String)" is implementation-dependent. While some implementations might make a copy of the internal character array of the original String object, others may implement it in a way that does not create a distinct copy.

Documented Use Case

The only documented use case for "new String(String)" is to create a new String object that represents the same sequence of characters as an existing String object. This is redundant, since Strings are immutable in Java.

Pitfalls of Assuming Implementation Details

It's crucial to avoid assuming that the implementation-specific behavior of "new String(String)" will be consistent across different Java implementations. Always refer to the documentation for the most accurate and reliable information.

Example of Implementation-Dependent Behavior

In the Apache Harmony implementation, "new String(String)" doesn't create a copy of the underlying character array. However, this behavior may vary in other Java implementations.

Conclusion

While the "new String(...)" syntax can be used to create a distinct copy of a String object, its purpose and effect can vary depending on the implementation of the Java virtual machine. It's essential to refer to the documentation and test your code in different environments to ensure the desired behavior.

The above is the detailed content of When and Why Use `new String(...)` in Java?. For more information, please follow other related articles on the PHP Chinese website!