int[] vs Integer[]

int[] vs Integer[] performance (primitive type vs wrapper type)

• object type은 비싸다.(그걸 배열로 모아두면 더 비싸겠지?)

  • 10억번의 반복문에서 object type이 43배 느린것을 확인.

• don't care about performance and want to do everything in an object oriented fashion, use Integer.

속도 & 메모리 테스트

int array test

Integer array test

@Test //usedMemory : 603455488 (6억)
void int_array_billion_init() { // 1억 : 309ms, 1.5억 : 378ms
    int hundredMillion = 150000000;
    int[] intArrays = new int[hundredMillion];
    for (int i = 0; i < hundredMillion; i++) {
        intArrays[i] = i + 1;
    }
}

@Test //usedMemory : 3051880448 (30억)
void integer_array_billion_init() { // 1억 : 356ms, 1.5억 : 944ms
    int hundredMillion = 150000000;
    Integer[] integerArrays = new Integer[hundredMillion];
    for (int i = 0; i < hundredMillion; i++) {
        integerArrays[i] = i + 1;
    }
}

참고 : https://stackoverflow.com/questions/4624933/comparing-performance-of-int-and-integer https://web.archive.org/web/20060423040119/http://www.glenmccl.com:80/tip_016.htm https://openwritings.net/pg/java/performance-primitive-data-type-vs-object-data-type-java