ArrayList：我想在我的arrayList中找到一个词
我有一个包含多个元素的 arrayList：
ArrayList<String> listName = new ArrayList<String>();
listName.add("julie");
listName.add("sandrine");
listName.add("toto");
用户输入一个名称，例如popo，该元素不存在。但是，我有几个打印，我不明白？
The word isn't find
The word isn't find
The word isn't find
我试着做一个算法：
import java.util.ArrayList;
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
ArrayList<String> listName = new ArrayList<String>();
listName.add("julie");
listName.add("sandrine");
listName.add("toto");
System.out.println("please enter your name : ");
String wordSearch = input.nextLine();
for (int i = 0; i < listName.size(); i++) {
if (listName.get(i).equals(wordSearch)){
System.out.println("The word is find : ");
} else {
System.out.println("The word isn't find ");
}
}
}
}
回答
如果只想打印一次，则需要执行以下操作：
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
ArrayList<String> listName = new ArrayList<String>();
listName.add("julie");
listName.add("sandrine");
listName.add("toto");
System.out.println("please enter your name : ");
String wordSearch = input.nextLine();
boolean isUserFound = false;
for (String s : listName) {
if (s.equals(wordSearch)) {
isUserFound =true;
break;
}
}
if(isUserFound)
System.out.println("The word is find : ");
else
System.out.println("The word isn't find : ");
}
首先找出用户是否存在，相应地设置一个标志并相应地打印结果。
或者您可以简单地通过以下方式替换循环：
if(listName.contains(wordSearch))
System.out.println("The word is find : ");
else
System.out.println("The word isn't find : ");
或者
if(listName.indexOf(wordSearch) != -1 )
System.out.println("The word is find : ");
else
System.out.println("The word isn't find : ");
这两种方法（即， contains和indexOf）都是列表集合的一部分，因此您无需重新实现该逻辑，只需使用已有的。
完整示例：
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
List<String> listName = new ArrayList<>();
listName.add("julie");
listName.add("sandrine");
listName.add("toto");
System.out.println("please enter your name : ");
String wordSearch = input.nextLine();
if(listName.contains(wordSearch))
System.out.println("The word is find : ");
else
System.out.println("The word isn't find : ");
}