使用String.join(CharSequence delimiter, CharSequence... elements)方法时，如果CharSequence...只有一个元素，结果是什么

当使用String.join(CharSequence delimiter, CharSequence... elements)方法时，如果CharSequence...只有一个元素，那么结果就是该元素本身，不会添加任何分隔符。例如：

String str = String.join(",", "hello");
System.out.println(str); // 输出：hello

相关问题

Static member 'java.lang.String.join(java.lang.CharSequence, java.lang.CharSequence...)' accessed via instance reference

The error message "Static member 'java.lang.String.join(java.lang.CharSequence, java.lang.CharSequence...)' accessed via instance reference" occurs when you try to call the static method `join` on an instance of the `String` class instead of calling it on the class itself.

The `join` method is used to join a group of strings together with a delimiter. It takes two parameters: a delimiter and an array of strings. Here is an example of how to use it:

String[] words = {"hello", "world", "how", "are", "you"};
String joinedWords = String.join(" ", words);
System.out.println(joinedWords);

In this example, we create an array of strings called `words`, and then use the `join` method of the `String` class to join the strings together with a space delimiter.

If you see the error message "Static member 'java.lang.String.join(java.lang.CharSequence, java.lang.CharSequence...)' accessed via instance reference", it means that you are calling the `join` method on an instance of the `String` class, rather than on the class itself. To fix the error, make sure you call the method on the class, like this:

String[] words = {"hello", "world", "how", "are", "you"};
String joinedWords = String.join(" ", words);
System.out.println(joinedWords);

Note that in the corrected code, we are calling the `join` method on the `String` class itself, not on an instance of the `String` class.

string.Join

String.join()方法是一个用于拼接字符串的方法。它使用指定的分隔符将多个字符串连接在一起。这个方法在JDK1.8之后才引入。当存在一个元素为null时，它会添加一个"null"字符串。\[1\]

下面是一个示例代码，展示了如何使用String.join()方法：

package com.java265.other;

public class TestStringJoin {
    public static void main(String\[\] args) {
        String\[\] arrs1 = { "this", "is", "java265.com" };
        String\[\] arrs2 = new String\[3\];
        arrs2\[0\] = "my";
        
        System.out.println("arrs1:" + String.join(",", arrs1));
        System.out.println("arrs2:" + String.join(",", arrs2));
    }
}

运行以上代码，将输出以下信息：

arrs1:this,is,java265.com
arrs2:my,null,null

String.join()方法有两种语法形式：

public static String join(CharSequence delimiter, CharSequence... elements)

或

public static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements)

其中，delimiter参数是每个元素之间要添加的分隔符，elements参数是需要添加分隔符的字符串。该方法返回拼接后的字符串。\[2\]\[3\]
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