在Java中構(gòu)建分隔項(xiàng)字符串的最佳方法是什么？在Java應(yīng)用程序中工作時(shí)，我最近需要組裝一個(gè)以逗號(hào)分隔的值列表，以傳遞給另一個(gè)Web服務(wù)，而不知道預(yù)先會(huì)有多少元素。我能想到的最好的辦法是：public String appendWithDelimiter( String original, String addition, String delimiter ) {
if ( original.equals( "" ) ) {
return addition;
} else {
return original + delimiter + addition;
}}String parameterString = "";if ( condition ) parameterString = appendWithDelimiter( parameterString, "elementName", "," );if ( anotherCondition ) parameterString = appendWithDelimiter( parameterString, "anotherElementName", "," );我意識(shí)到這并不是特別有效，因?yàn)榈教幎荚趧?chuàng)建字符串，但我追求的是清晰而不是優(yōu)化。在Ruby中，我可以這樣做，這感覺(jué)更優(yōu)雅：parameterArray = [];parameterArray << "elementName" if condition;parameterArray << "anotherElementName" if anotherCondition;parameterString = parameterArray.join(",");但是因?yàn)镴ava缺少一個(gè)JOIN命令，所以我找不到任何類似的東西。那么，用Java做這件事最好的方法是什么呢？
3 回答
紅糖糍粑
TA貢獻(xiàn)1815條經(jīng)驗(yàn) 獲得超6個(gè)贊
預(yù)Java 8：
StringUtils.join(java.lang.Iterable,char)
Java 8：
StringJoinerString.join()
StringJoiner joiner = new StringJoiner(",");joiner.add("01").add("02").add("03");String joinedString = joiner.toString(); // "01,02,03"String.join(CharSequence delimiter, CharSequence... elements))
String joinedString = String.join(" - ", "04", "05", "06"); // "04 - 05 - 06"String.join(CharSequence delimiter, Iterable<? extends CharSequence> elements)
List<String> strings = new LinkedList<>();strings.add("Java");strings.add("is");strings.add("cool");String message = String.join(" ", strings);//message returned is: "Java is cool"
慕仙森
TA貢獻(xiàn)1827條經(jīng)驗(yàn) 獲得超8個(gè)贊
public static String join(List<String> list, String delim) {
StringBuilder sb = new StringBuilder();
String loopDelim = "";
for(String s : list) {
sb.append(loopDelim);
sb.append(s);
loopDelim = delim;
}
return sb.toString();} List<String> list = new ArrayList<String>();
if( condition ) list.add("elementName");
if( anotherCondition ) list.add("anotherElementName");
join(list, ",");
慕斯709654
TA貢獻(xiàn)1840條經(jīng)驗(yàn) 獲得超5個(gè)贊
"My pets are: " + Joiner.on(", ").join(Arrays.asList("rabbit", "parrot", "dog")); // returns "My pets are: rabbit, parrot, dog"Joine
r.on(" AND ").join(Arrays.asList("field1=1" , "field2=2", "field3=3"));// returns "field1=1 AND field2=2 AND field3=3"Joiner.on(",").ski
pNulls().join(Arrays.asList("London", "Moscow", null, "New York", null, "Paris"));// returns "London,Moscow,New York,Paris"Joiner.on(", ").
useForNull("Team held a draw").join(Arrays.asList("FC Barcelona", "FC Bayern", null, null, "Chelsea FC", "AC Milan"));// returns "FC Barcel
ona, FC Bayern, Team held a draw, Team held a draw, Chelsea FC, AC Milan"添加回答
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