Java 将字符串转换为 List<Long>
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Convert string to List<Long>
提问by user2986404
I have a string with comma separated value that I am getting direclty from database. Now I want to pass that entire string to another query but the datatype required is long and i want to use in clause to get this done.
我有一个逗号分隔值的字符串，我直接从数据库中获取。现在我想将整个字符串传递给另一个查询，但所需的数据类型很长，我想使用 in 子句来完成这项工作。
str1 = [123,456,789];
Is there any direct way to do it instead of looping.
有没有什么直接的方法可以做到而不是循环。
采纳答案by Kamlesh Arya
With guava:
随着番石榴：
List<Long> longs = Lists.newArrayList(Iterables.transform(Splitter.on(',').split("1,2,3"), new Function<String, Long>() {
public Long apply(final String in) {
return in == null ? null : Longs.tryParse(in);
}
}));
EDIT:
编辑：
With a List<String>(stringList) as input:
以List<String>( stringList) 作为输入：
List<Long> longs = Lists.newArrayList(Lists.transform(stringList, new Function<String, Long>() {
public Long apply(final String in) {
return in == null ? null : Longs.tryParse(in);
}
}));
回答by Kamlesh Arya
you can try below code to get long value from a string
您可以尝试以下代码从字符串中获取长值
if str1="123,456,789"
如果 str1="123,456,789"
Long x=Long.parseLong(str1.replace(",",""));
and,
和，
if str1="[123,456,789]"
如果 str1="[123,456,789]"
Long x=Long.parseLong(str1.replace(",|\[|\]",""));
回答by Ankur Shanbhag
I doubt that you can do this without looping. Here is a sample workaround:
我怀疑您是否可以在不循环的情况下执行此操作。这是一个示例解决方法：
String str = "[123,456,789]";
Pattern pattern = Pattern.compile("\d+");
Matcher matcher = pattern.matcher(str);
List<Long> list = new ArrayList<Long>();
while (matcher.find()) {
System.out.println(matcher.group());
list.add(Long.parseLong(matcher.group())); // Add the value to the list
}
System.out.println(list);
回答by thermite
Use String.replace assuming str1 contains "[123,123,123]"
使用 String.replace 假设 str1 包含“[123,123,123]”
str1 = str1.replace(",|\[|\]",""); //should replace commas and brackets with nothing;
then you should be able to do
那么你应该能够做到
Long myLong = Long.parseLong(str1);
回答by Vignesh
Use StringTokenizer and add split tokens to a list with a while loop.
使用 StringTokenizer 并使用 while 循环将拆分标记添加到列表中。
StringTokenizer st = new StringTokenizer("1,2,3", ",");
List<Long> list = new ArrayList<Long>();
while (st.hasMoreTokens())
{
list.add(Long.valueOf(st.nextToken()));
}
回答by virag
You can use the Lambda functions of Java 8 to achieve this without looping
您可以使用 Java 8 的 Lambda 函数来实现此目的而无需循环
String string = "1, 2, 3, 4";
List<Long> list = Arrays.asList(string.split(",")).stream().map(s -> Long.parseLong(s.trim())).collect(Collectors.toList());
回答by Bienvenido David
A little shorter than virag's answer, as it skips asList() and doesn't do a string trim.
比 virag 的答案短一点，因为它跳过 asList() 并且不进行字符串修剪。
List<Long> list = Arrays.stream(str.split(",")).map(Long::valueOf).collect(Collectors.toList());
