在 Java 中将 List<String> 转换为 String[]
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Converting List<String> to String[] in Java
提问by Christian
How do I convert a listof String into an array? The following code returns an error.
public static void main(String[] args) {
List<String> strlist = new ArrayList<String>();
strlist.add("sdfs1");
strlist.add("sdfs2");
String[] strarray = (String[]) strlist.toArray();
System.out.println(strarray);
}
Error:
错误：
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.String;
at test.main(test.java:10)
采纳答案by jjujuma
You want
你要
String[] strarray = strlist.toArray(new String[0]);
See herefor the documentation and note that you can also call this method in such a way that it populates the passed array, rather than just using it to work out what type to return. Also note that maybe when you print your array you'd prefer
有关文档，请参见此处，并注意您还可以通过填充传递的数组的方式调用此方法，而不仅仅是使用它来确定要返回的类型。另请注意，也许当您打印数组时，您更喜欢
System.out.println(Arrays.toString(strarray));
since that will print the actual elements.
因为这将打印实际元素。
回答by crazyscot
List.toArray()necessarily returns an array of Object. To get an array of String, you need to use the casting syntax:
List.toArray()必然返回一个对象数组。要获取字符串数组，您需要使用转换语法：
String[] strarray = strlist.toArray(new String[0]);
See the javadoc for java.util.List for more.
有关更多信息，请参阅 java.util.List 的 javadoc。
回答by Paul
public static void main(String[] args) {
List<String> strlist = new ArrayList<String>();
strlist.add("sdfs1");
strlist.add("sdfs2");
String[] strarray = new String[strlist.size()]
strlist.toArray(strarray );
System.out.println(strarray);
}
回答by dfa
回答by Arthur
hope this can help someone out there:
希望这可以帮助那里的人：
List list = ..;
列表列表 = ..;
String [] stringArray = list.toArray(new String[list.size()]);
String [] stringArray = list.toArray(new String[list.size()]);
great answer from here: https://stackoverflow.com/a/4042464/1547266
来自这里的好答案：https: //stackoverflow.com/a/4042464/1547266
回答by phil
String[] strarray = strlist.toArray(new String[0]);
String[] strarray = strlist.toArray(new String[0]);
if u want List convert to string use StringUtils.join(slist, '\n');
如果你想列表转换为字符串使用 StringUtils.join(slist, '\n');
