·

78.98K

· mufid

Problem: I want a map that store integer as its value. Now i
have two approaches:

1. Use anything as key and Integer (non-primitive integer) as value, or
2. Use anything as key and a class that contains int (primitive integer) as value.

Which should i use? The first solution seems pretty neat, nothing
to do. Just instatiate new Integer and done. At the other hand,
performance wise, it will do unnecessary boxing/unboxing if
not properly handled. Remember that we only able to use primitive
integer to do calculation and primitive integer to store value
to the map.

The Test

Benchmark withBoxing = new Benchmark() {
 public void run() {
 Map<String, Integer> a = new HashMap<String, Integer>();

 // Simulate much boxing
 for (int i = 0; i < MAX; i++) {
 a.put("" + i, i);
 }

 // Simulate much unboxing
 for (int i = 0; i < MAX; i++) {
 // A hack so that JVM does not optimize this code.
 hack += a.get("" + i); 
 hack = hack % 1000;
 }
 }
};
Benchmark encapsulate = new Benchmark() {
 public void run() {
 Map<String, EncapsulatedInteger> a = new HashMap<String, EncapsulatedInteger>();

 // No boxing/unboxing, but new class
 for (int i = 0; i < MAX; i++) {
 a.put("" + i, new EncapsulatedInteger(i));
 }

 for (int i = 0; i < MAX; i++) {
 // A hack so that JVM does not optimize this code.
 hack += a.get("" + i).v; 
 hack = hack % 1000;
 }
 }
};

The run command

javac MapPerf.java; java -Xmx1024m -cp . MapPerf

The Result

$ javac MapPerf.java; java -Xmx1024m -cp . MapPerf
Boxing/unboxing: 10973 ms
Encapsulation: 7036 ms

Summary

With Integer as value, the routine is 50% slower because of unnecessary
boxing/unboxing

Github

https://github.com/mufid/boxing-unboxing-java-perf

Related protips

Have a fresh tip? Share with Coderwall community!

Post

Post a tip

Sponsored by

#native_company#

#native_desc#

#native_cta#

Post a job for only 299ドル

Sponsored by #native_company# — Learn More