Java 需要帮助修复while循环吗

嗨，我试图创建一个模拟数据库搜索，尽管它可以工作，但每当我输入一个不属于数据库的输入时，它就会在线程“main”java.lang.ArrayIndexOutOfBoundsException:4的第23行中创建一个异常。我不知道还能做什么，因为我看不到代码中有错误

import java.util.*;

public class Database {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner scan = new Scanner(System.in);
    String[] names = new String[4];

    boolean found = false;
    int i = 0;
    names[0] = "Thor";
    names[1] = "Ben";
    names[2] = "Zoe";
    names[3] = "Kate";

    System.out.println("Enter Player Name");
    String input = scan.nextLine();

    while(found != true){

        if(input.equals(names[i])){
            System.out.println(input + " has been found");
            found = true;
        } else {
            i = i+1;
        }
        if(i == 3 && found == false){
            System.out.println(input + " was not found");
        }

      }

    }

  }

---

打印未找到的

input+”后，您不会离开循环“

。 因此，循环的下一次迭代将抛出

ArrayIndexOutOfBoundsException

您应该在完成整个阵列的测试后离开循环

改变

    while(found != true){

到

while（！found&&i

实际上，您可以移动if语句来测试输入是否在循环之后：

  while(!found && i < names.length) {
    if(input.equals(names[i])){
        System.out.println(input + " has been found");
        found = true;
    } else {
        i = i+1;
    }
  }
  if(!found){
      System.out.println(input + " was not found");
  }

while（！found&&i

更好的选择是使用for循环：

  for (int i = 0; i < names.length && !found; i++) {
    if(input.equals(names[i])){
        System.out.println(input + " has been found");
        found = true;
    }
  }
  if(!found){
      System.out.println(input + " was not found");
  }

for（int i=0；i

将while循环更改为

    while (found != true) {

        if (input.equals(names[i])) {
            System.out.println(input + " has been found");
            found = true;
        } else {
            i = i + 1;
        }
        if (i == 4 && found == false) {   //changed here

            System.out.println(input + " was not found");
            //or found == true;
            break;           //and here
        }

    }

如果此条件为真，则需要退出循环

i == 4 && found == false

要真正退出，你必须“打破”while条件

found != true

您可以通过设置

found=true

（但这在语义上不正确）或添加

break

指令来完成此操作

以下是while循环的替代解决方案：

    while (!found && i<4) 
        if (input.equals(names[i++]))found = true;
    System.out.println(input+(found?" has been":" was not")+" found");

---

while（！found&&i如果您的输入与i的值不匹配，我将继续递增，并且您的数组长度为4。显然，ArrayindexoutofException。
为了避免你也需要考虑数组长度。
 你可以简单地更改为

while(i < names.length)

顺便说一句，你可以做
i++
（而不是
i=i+1
）和
！found
（而不是
found==false
）；谢谢！它非常有效。我将在我的完整数据库中记住它。这是一个测试所需概念的实践。
while(i < names.length)

if (input.equals(names[i])) {
    System.out.println(input + " has been found");
    break;
}