Java 无法向 Character ArrayList 添加字符
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Can't add chars to Character ArrayList
提问by user3807322
I'm having issues understanding ArrayList in Java. I tried to declare a Character ArrayList and add a char at 0, but it returned error at list.add(0, "B") line.
我在理解 Java 中的 ArrayList 时遇到问题。我试图声明一个 Character ArrayList 并在 0 处添加一个字符，但它在 list.add(0, "B") 行返回错误。
public class ArrListTest {
public static void main(String[] args) {
ArrayList<Character> list;
list.add(0, "B");
}
}
Also I'm having issues reversing a string. Is there a way to reverse a string without using a loop?
另外我在反转字符串时遇到问题。有没有办法在不使用循环的情况下反转字符串？
采纳答案by Pshemo
"B"is instance of String, characters need to be surrounded with 'like 'B'.
"B"是 String 的实例，字符需要用'like包围'B'。
use
用
list.add(0,'B');
If you want to add Bafter last element of list skip 0
如果要B在列表的最后一个元素后添加跳过0
list.add('B');
Also don't forget to actually initialize your list
也不要忘记实际初始化您的列表
List<Character> list = new ArrayList<>();
// ^^^^^^^^^^^^^^^^^^^
To know why I used List<Character> listas reference type instead of ArrayList<Character> listread:
What does it mean to “program to an interface”?
要知道为什么我使用List<Character> list引用类型而不是ArrayList<Character> list阅读：
“编程到接口”是什么意思？
回答by Reimeus
回答by KARTHIK SARAGADAM
public static void main(String args[]) {
ArrayList list= new ArrayList();
list.add("B");
}
try this
尝试这个
回答by KARTHIK SARAGADAM
public class stackQuestions {
公共类堆栈问题{
public static void main(String args[]) {
ArrayList list = new ArrayList();
list.add("b");
list.add(0, "a");// it will add to index 0
list.add(0, "c");// it will replaces to index 0
System.out.println(list);
}
}
}
