System.currentTimeMillis() vs. System.nanoTime(): Which is Best for Precise Game Object Positioning?

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

When dealing with object positioning updates in a game, the choice between using System.currentTimeMillis() and System.nanoTime() becomes crucial. While both methods provide time measurements, their accuracy and precision differ.

Precision vs. Accuracy

Precision refers to the smallest unit of time that can be measured, while accuracy refers to how close the measurement is to the actual time. System.currentTimeMillis() returns milliseconds, while System.nanoTime() returns nanoseconds, indicating that System.nanoTime() is more precise.

System Resolution Issues

As mentioned in the question, different operating systems have varying time resolution. Windows has a reported resolution of 50ms, while Mac/Linux have a resolution of approximately 1ms. This means that measurements on Windows using System.currentTimeMillis() could have up to 50ms of inaccuracy.

Suitable Choice for Precise Measurements

Since the primary goal is to achieve the most precise measurements possible for object positioning, it is recommended to use System.nanoTime(). It provides nanosecond precision, enabling more accurate time measurements and smoother object movement in your game.

Code Example

To demonstrate, the following code measures the execution time of a task using System.nanoTime():

long startTime = System.nanoTime();
// ... code to be measured ...
long estimatedTime = System.nanoTime() - startTime;

By subtracting the startTime from the current time, we obtain the elapsed time with nanosecond precision.

Additional Notes

• Stability: System.nanoTime() is generally considered more stable than System.currentTimeMillis(), as it is not susceptible to system clock adjustments.
• Overflow: While System.nanoTime() returns a long value, it can reach its maximum value and overflow. Take precautions to handle this potential issue.
• Portability: System.nanoTime() is not available in all Java environments. Consult the Java documentation for details.

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