java Utils

集合#

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        CollectionUtils.isNotEmpty(null);

数字#

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        NumberUtils.isParsable(" ");

字符串#

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        StringUtils.isNotBlank("");

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        String join = String.join("-", "2018", "08", "09");
        System.out.println(join);

结果：

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2018-08-09

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        List<String> list = Arrays.asList("java", "python", "nodejs", "ruby");
        String result = String.join(", ", list);
        System.out.println(result);
        //out:
        //java, python, nodejs, ruby

不同时间格式之间的转换#

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        Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(inventoryTime);
        String dateStr = new SimpleDateFormat("yyyyMMddHHmmss").format(date);

随机数#

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        int size=10;//输出个数
        int min=12;//最小值
        int max=15;//最大值
        new Random().ints(size, min, max+1).forEach(System.out::println);

MultiValuedMap#

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        MultiValuedMap<String,String> map =new ArrayListValuedHashMap();
        map.put("a","qq");
        map.put("a","qq");
        map.put("a","ss");
        map.put("a","dd");
        map.put("b","re");
        map.put("b","fs");
        Collection<String> a = map.get("a");
        a.forEach(System.out::println);
        //enrty
        map.entries().forEach(System.out::println);

結果：

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qq
qq
ss
dd
a=qq
a=qq
a=ss
a=dd
b=re
b=fs