版本信息

• 仓颉版本 0.53.18
• Golang版本 1.22.8
• Java版本 corretto-1.8.0_452

源码

仓颉

package cangjie_test

import std.collection.ArrayList
import std.time.MonoTime

main() {
    let start = MonoTime.now()
    let num = 1000000
    let extendCounts = ArrayList<Int>() // 分别扩容次数
    for (i in 1..11) {
        extendCounts.append(arrayListExtend(num))
    }

    println("耗时: ${(MonoTime.now()-start).toMilliseconds()} ms")
    println("分别扩容次数: ${extendCounts}")
}

func arrayListExtend(arrNum: Int): Int {
    let arrList = ArrayList<Int>()
    var extendCount = 0
    var tmpCapacity = arrList.capacity()
    for (i in 1..arrNum + 2) {
        arrList.append(i)
        if (tmpCapacity != arrList.capacity()) {
            extendCount++
            tmpCapacity = arrList.capacity()
        }
    }

    return extendCount
}

Golang

package main

import (
	"fmt"
	"time"
)

func main() {
	start := time.Now()
	num := 1000000
	var extendCounts []int // 分别扩容次数
	for i := 1; i < 11; i++ {
		extendCounts = append(extendCounts, arrayListExtend(num))
	}

	fmt.Printf("耗时: %d ms\n", time.Now().Sub(start).Milliseconds())
	fmt.Printf("分别扩容次数: %v", extendCounts)
}

func arrayListExtend(arrNum int) int {
	var arrList []int
	var extendCount = 0
	var tmpCapacity = cap(arrList)
	for i := 1; i < arrNum+2; i++ {
		arrList = append(arrList, i)
		if tmpCapacity != cap(arrList) {
			extendCount++
			tmpCapacity = cap(arrList)
		}
	}

	return extendCount
}

Java

package java_test;

import java.util.*;
import java.lang.reflect.*;

public class Main {
    public static void main(String[] args) throws Exception {
        final long start = System.currentTimeMillis();
        int num = 1000000;
        final ArrayList<Integer> extendCounts = new ArrayList();
        for (int i = 1; i < 11; i++) {
            extendCounts.add(arrayListExtend(num));
        }

        System.out.println(String.format("耗时: %d ms", System.currentTimeMillis() - start));
        System.out.println(String.format("分别扩容次数: %s", extendCounts));
    }

    static int arrayListExtend(int arrNum) throws Exception {
        final ArrayList<Integer> arrList = new ArrayList();
        int extendCount = 0;
        Class<? extends List> clazz = arrList.getClass();
        Field field = clazz.getDeclaredField("elementData");
        field.setAccessible(true);
        int tmpCapacity = ((Object[]) field.get(arrList)).length;
        int _tmpCapacity = tmpCapacity;
        for (int i = 1; i < arrNum + 2; i++) {
            arrList.add(i);
            if ((_tmpCapacity = ((Object[]) field.get(arrList)).length) != tmpCapacity) {
                extendCount++;
                tmpCapacity = _tmpCapacity;
            }
        }

        return extendCount;
    }
}

结果

• Java 112 ms 扩容次数 30
• Golang 76 ms 扩容次数 38
• 仓颉 非优化结果 649 ms 扩容次数 28
• 仓颉 O1优化结果 121 ms 扩容次数 28
• 仓颉 O2优化结果 94 ms 扩容次数 28
• 仓颉 Oz优化结果 97 ms 扩容次数 28

总结

仓颉仍需努力