Is Java's Double Brace Initialization Efficient, and What Are the Alternatives?

Efficiency of Java "Double Brace Initialization"

The inconspicuousness of Java's "Double Brace Initialization" conceals the creation of an anonymous inner class with an instance initializer to facilitate effortless object construction. Despite this alluring simplicity, concerns arise regarding its potential performance impact and excessive file generation.

Efficiency Considerations

Experiments conducted reveal a discernible performance gap between double brace initialization and direct list instantiation. Notably, double brace initialization incurs an execution time of about 190 milliseconds, in contrast to the rapid initialization achieved through direct instantiation.

Class File Clutter

One drawback associated with double brace initialization is the proliferation of class files it generates. This can result in program jar file bloating and marginally slower class loading. Additionally, double brace initialization may introduce memory overhead due to the abundance of classes loaded into the Java Virtual Machine.

Obscurity in Production Code

While the double brace initialization syntax is technically sound, it may be deemed unnecessarily obscure for production code. However, it remains a valuable tool for exploring Java's semantic nitty-gritty or demonstrating its expressive power.

Alternative Approaches

Consider alternatives such as Arrays.asList, varargs methods, and Google Collections' concise list construction notations. Additionally, Java 9 introduces a convenient set literal syntax, eliminating the need for double brace initialization altogether.

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