Java中数组转字符串的五种方式效率比较

拼搏现实的明天。 2024-03-17 13:39 24阅读 0赞

@Test
        public void listToString() {
            ArrayList<String> longList = new ArrayList<>();
            for (int i = 0; i < 10; i++) {
                longList.add(String.valueOf(i));
            }
            //方法1
            long startTime1 = System.currentTimeMillis();
            String join1 = getString1(longList);
            long endTime1 = System.currentTimeMillis();
            log.info("方法一耗时:数据量:{},耗时{}", longList.size(), (endTime1 - startTime1));
    
            long startTime2 = System.currentTimeMillis();
            //方法2
            String join2 = getString2(longList);
            long endTime2 = System.currentTimeMillis();
            log.info("方法二耗时:数据量:{},耗时{}", longList.size(), (endTime2 - startTime2));
    
            long startTime3 = System.currentTimeMillis();
            //方法3
            String join3 = getString3(longList);
            long endTime3 = System.currentTimeMillis();
            log.info("方法三耗时:数据量:{},耗时{}", longList.size(), (endTime3 - startTime3));
    
    
            long startTime4 = System.currentTimeMillis();
            //方法4
            String join4 = getString4(longList);
            long endTime4 = System.currentTimeMillis();
            log.info("方法四耗时:数据量:{},耗时{}", longList.size(), (endTime4 - startTime4));
    
    
            long startTime5 = System.currentTimeMillis();
            //方法5
            String join5 = getString5(longList);
            long endTime5 = System.currentTimeMillis();
            log.info("方法四耗时:数据量:{},耗时{}", longList.size(), (endTime5 - startTime5));
    
            log.info("原始数据:{}",longList);
            log.info(join1);
            log.info(join2);
            log.info(join3);
            log.info(join4);
            log.info(join5);
        }
    
    
        //方法1
        public static String getString1(List<String> strList) {
            if (CollectionUtils.isEmpty(strList)) {
                return "";
            }
            return strList.stream().collect(Collectors.joining(","));
        }
    
        //方法2
        @NotNull
        private static String getString2(ArrayList<String> longList) {
            return StringUtils.collectionToCommaDelimitedString(longList);
        }
    
        //方法3
        private static String getString3(ArrayList<String> longList) {
            return org.apache.commons.lang3.StringUtils.join(longList, ",");
        }
    
    
        //方法4
        private static String getString4(ArrayList<String> longList) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < longList.size(); i++) {
                sb.append(i);
                if (i < longList.size() - 1) {
                    sb.append(",");
                }
            }
            return String.valueOf(sb);
        }
    
    
        //方法5
        private static String getString5(ArrayList<String> longList) {
            return String.join(",", longList);
        }

话不多说,上运行结果

![b74a5fe83f1841329b5a5a0c0f12c0eb.png][]

注意 方法一跟方法五，如果数组是其它类型的 还需要转成String类型才能使用,如下

longList.stream().map(a -> String.valueOf(a)).collect(Collectors.toList());

耗时对比

### 数量级 百 ###

![8e68cbd6b92647fc988407cc310d342a.png][]

结果:运行多次五种方式每次运行结果耗时相差不大

结论:运行多次效率比方法四=方法五>方法二>方法三>>方法一

### 数量级 千 ###

![12a2453431cc459b970bb86d23296a53.png][]

![ea1b629715f34947925e9c0b52eb734b.png][]

结果:运行多次五种方式每次运行结果耗时相差不大

结论:运行多次效率比方法四>=方法五>方法二>方法三>>方法一

### 数量级 万 ###

![7e3a452f295a4fb0863ea1b5de30f8f1.png][]

![bf9cdf5257124189a476d9de300d64ad.png][]

![75021138c3d842e18e0585fe604856a1.png][]

结果:运行多次五种方式每次运行结果耗时相差不大

结论:运行多次效率比方法四=方法五>方法二>方法三>>方法一

### 数量级 十万 ###

![606024c01d324219a5426d5fa9d65e31.png][]

![5d71db96976e488794e9819fe085cbf5.png][]

![e00010afcc0e4d48b560a46a39027ee7.png][]

结果:运行多次,其中方法五效率明显高于其它四种方法,方法二、方法三、方法四效率相差不大各有胜负，方法一效率最差远低于其它四种方法

结论:,方法五>方法二>=方法三>=方法四>>方法一

### 数量级 百万 ###

![c9d0c7ac0ca84101b0e66ecfbff12752.png][]

![8193d370d3f9459c8027292ae4539962.png][]

![013b7f8b121f40549e6a6f387e3a7d40.png][]

![de0145abbe80465cbed02c6e75682ed1.png][]

![9d404c8992714fc68d4d4930333ffc71.png][]

![5e7160d3c3d543f8b49bad21f4801e36.png][]

结果:运行多次,其中方法五效率依然高于其它四种方法,方法二、方法三、方法四效率比较接近 方法三略占优，方法一效率最差

结论:,方法五>=方法三>方法二>方法四>方法一

### 数量级 千万 ###

![cd87a054987942dd97ab9589af6a02db.png][]

### ![7ee918d8bc8c45ab81afa1f93b82d027.png][] ###

![1fdd5008ca1344678ff2d9e739a7da7e.png][]

结果:运行多次,其中方法五效率依然高于其它四种方法，除了方法一，其它四种方法 计算数据量高了10倍，但耗时普遍增加了10---30倍，

结论:,方法五>方法一>>方法四=方法三>方法二

其它说明:如果是实时交互业务，当前响应时间已经影响用户体验

最后总结:方法五对于千万级别计算 远高于其它四种方式

String.join(",", longList)

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