我想在数组中找到字符串的索引

Question

我必须从用户输入的数组中搜索一个字符串，但我的逻辑有错误。即使用户输入在数组中，我仍然会得到“找不到数据”

我还必须显示字符串在数组中的索引，如果它被发现但那里也有错误。

以下是我尝试过的代码。

这是最初的问题

1. 创建一个要求用户插入 5 个名称的程序。
2. 在数组中存储名称
3. 要求用户插入他们想从之前创建的列表中找到的名称
4. 如果找到名称，则显示“在 [index] 找到的数据”
5. 如果没有，则显示“未找到数据”。暗示;使用 Java 方法 equals 比较两个字符串。

package stringsearch;
import java.util.Scanner;

public class StringSearch 
{
    public static void main(String[] args)
    {
        int i;
        Scanner sc = new Scanner(System.in);

        String [] names = new String[5];

        for (i = 0; i < names.length; i++) 
        {
            System.out.print("Enter name " + (i + 1) + " > ");

            names[i] = sc.nextLine();
        }

        System.out.print("Input Name to compare > ");
        String inName = sc.nextLine();

            if (names.equals(inName)){

              System.out.println("Data found at ["+i+"]");

            }

            else 
            {

              System.out.println("Data not found!");

            }

    }
}

Answer 1

您需要将inName 的值与存储在数组中的每个值进行比较，而不是与数组本身进行比较。您可以使用以0 开头的索引访问存储在数组中的每个值。

for (i = 0; i < names.length; i++) {
    if (inName.equals(names[i])) {
        System.out.println("Data found at [" + i + "]");
        break;
    }
}

// If the value stored in `inName` is found, the value of `i` will not reach up
// to the value equal to `names.length` because of the `break` statement. If the
// value of `i` has reached there, it means that the value stored in `inName`
// has not been found.
if (i == names.length) {
    System.out.println("Data not found!");
}

完整程序：

import java.util.Scanner;

public class StringSearch {
    public static void main(String[] args) {
        int i;
        Scanner sc = new Scanner(System.in);
        String[] names = new String[5];

        for (i = 0; i < names.length; i++) {
            System.out.print("Enter name " + (i + 1) + " > ");
            names[i] = sc.nextLine();
        }

        System.out.print("Input Name to compare > ");
        String inName = sc.nextLine();

        for (i = 0; i < names.length; i++) {
            if (inName.equals(names[i])) {
                System.out.println("Data found at [" + i + "]");
                break;
            }
        }

        // If the value stored in `inName` is found, the value of `i` will not reach up
        // to the value equal to `names.length` because of the `break` statement. If the
        // value of `i` has reached there, it means that the value stored in `inName`
        // has not been found.
        if (i == names.length) {
            System.out.println("Data not found!");
        }
    }
}

示例运行：

Enter name 1 > John
Enter name 2 > Harry
Enter name 3 > Sam
Enter name 4 > Cristina
Enter name 5 > Manny
Input Name to compare > Sam
Data found at [2]

Answer 2

您将整个数组与单个字符串进行比较，该字符串将始终返回 false。

同理：

  String[] names = {"a", "b", "c"};
  names.equals("d");

遍历数组看是否有字符串

 int i = 0;
 for (String item: names) {
     if (item.equals(inName) ) {
         return i;
     }
     i++
  }
  if (i == names.length ) {
    // not found 
  }

运行示例：

public class A {
  public static void main(String...args){
    String[] names = {"a", "b", "c"};
    String inName = "d";

     int i = 0;
     for (String item: names) {
      if (item.equals(inName) ) {
        System.out.println(i);
        break;
         //return i;
      }
      i++;
    }
    if (i == names.length ) {
       System.out.println(-1);
        // not found
    }
  }
}