“名称不匹配”打印，但在此打印5次

编程问答 2022-06-11

问题描述

当我键入数组列表中没有的内容时，“名称不匹配”将打印5次。我只想打印一次。

  1. 哪行代码使“名称不匹配”打印5次？
  2. 如何仅打印1次“名称不匹配”？
public class Arrays {
    public static void main(String[] args) {

String[] names = {"Meisam","Raju","Sasi","Aju","Ram"};
        int[] numbers = {123456,654321,345678,953456,123445};
        for (int i = 0; i < names.length; i++) {
            System.out.println(names[i]);
        }

        System.out.println("Please Enter a Name:  ");
        Scanner scanner = new Scanner(system.in);
        String name = scanner.next();

        for(int i = 0; i < names.length; i++){
            if(name.equals(names[i])) {
                System.out.println(numbers[i]);
            } else {
                System.out.println("Names Doesn't Match!");
            }
            }
        }
    }

输出为：

Meisam
Raju
Sasi
Aju
Ram
Please Enter a Name:  
raj //input a keyword called 'raj' 
Names Doesn't Match!
Names Doesn't Match!
Names Doesn't Match!
Names Doesn't Match!
Names Doesn't Match!

解决方法

哪一行代码使“名称不匹配”打印5次？

for(int i = 0; i < names.length; i++) {
   // ...
}

它将为数组中的每个元素打印Names Doesn't Match!。如果数组包含例如10个元素，那么您将看到10次此消息。

如何仅打印1次“名称不匹配”？

只需首先检查整个数组，然后在是否找到名称的地方设置a marker。只有在此之后，maker is false才打印消息。

int j = -1;    // j == -1 -> means NOT_FOUND

for (int i = 0; i < name.length(); i++) {
    if (name.equals(names[i])) {
        j = i;
        break;
    }
}

System.out.println(j == -1 ? "Names Doesn't Match!" : numbers[j]);

对于此问题，我认为最好使用Map：

public static void main(String... args) {
    Map<String,Integer> nameNumber = Map.of(
            "Meisam",123456,"Raju",654321,"Sasi",345678,"Aju",953456,"Ram",123445);

    nameNumber.keySet().forEach(System.out::println);

    System.out.print("Please Enter a Name:  ");
    String name = new Scanner(System.in).next();
    Integer number = nameNumber.get(name);
    System.out.println(number == null ? "Names Doesn't Match!" : number);
}
,

更改代码以设置一个布尔值，并在循环后对其求值。

此外，您可以在发现循环后立即退出循环。

boolean found = false;
for(int i = 0; i < names.length; i++){
    if(name.equals(names[i])) {
        System.out.println(numbers[i]);
        found = true;
        break;
    }
}

if (!found){
      System.out.println("Names Doesn't Match!");
}
,

删除for循环中的其他部分 添加System.exit（0）; for循环中if块内部的最后一行 添加System.out.println（“名称不匹配！”）;在for循环之后

, 
for(int i = 0; i < names.length; i++) {
    if(name.equals(names[i])) {
        System.out.println(numbers[i]);
    } else {
        System.out.println("Names Doesn't Match!");
    }
}

使您的代码将字符串打印5次。这样做是因为您要遍历names数组的所有5个元素。

我建议，如果要打印一次，可以将其放入函数中，并在返回"Names Doesn't Match!时返回匹配的结果

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