System.currentTimeMillis() vs. System.nanoTime(): Which Java Method Should You Use for Precise Time Measurement?

System.currentTimeMillis vs. System.nanoTime: Precision and Accuracy in Time Measurement

When dealing with precise timekeeping in Java, the two dominant methods are System.currentTimeMillis() and System.nanoTime(). This article explores the nuances between these methods, addressing their accuracy, precision, and suitability for specific applications.

Accuracy vs. Precision

In time measurement, accuracy refers to how close a measured value is to the true value, while precision refers to the level of detail in the measurement. System.currentTimeMillis() provides millisecond-level accuracy, while System.nanoTime() offers nanosecond-level precision.

System.currentTimeMillis

System.currentTimeMillis() is often used for general timestamps. It provides a time measurement in milliseconds since a fixed point in the past (the epoch). This method is relatively accurate, especially for measuring periods longer than a few milliseconds. However, it may have lower accuracy on operating systems with limited time-keeping resolution, such as Windows.

System.nanoTime

System.nanoTime() offers extremely precise time measurements, but its accuracy is not guaranteed. It provides a nanosecond-level measurement relative to an arbitrary point in time. This method is ideal for precise measurements of elapsed time, such as when benchmarking code or tracking movement in a game.

Choice for Game Object Positioning

In the context of updating object positions in a game, where the change in movement is directly proportional to elapsed time, precision is crucial. System.nanoTime() would be the preferred choice due to its nanosecond-level resolution, which enables precise tracking of movement.

Conclusion

For general timestamps, System.currentTimeMillis() may suffice. But when precision is critical, as in the case of object positioning in a game, System.nanoTime() provides the necessary high-resolution time measurement capabilities. Developers should choose their method based on the level of accuracy and precision required for their application.

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