在本文中，我们将看到一个使用Java编程语言实现的菜单驱动程序，用于检查输入的字符是数字、字符串还是特殊字符。我们将使用switch case来实现这个应用程序。
向您展示一些实例
实例-1
Suppose the entered character is ‘a’ then the output should be “Entered character is a String”.
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Instance-2
的中文翻译为：
实例-2
Suppose the entered character is ‘1’ then the output should be “Entered character is a number”.
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Instance-3
的中文翻译为：
实例-3
Suppose the entered character is ‘$’ then the output should be “Entered character is a Special character”.
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语法
在Java中，我们使用isLetter、isDigit或isWhitespace函数来检查一个字符是字符串、数字还是特殊字符。使用isLetter函数来检查字符串，使用isDigit函数来检查数字，使用isLetter、isDigit和isWhitespace函数的组合来检查特殊字符。
以下是字符串函数的语法
Character.isLetter(ob1)
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以下是数字函数的语法
Character.isDigit(ob1)
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以下是字符串函数的语法
(!Character.isDigit(ob1)&& !Character.isLetter(ob1)&& !Character.isWhitespace(ob1))
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算法
步骤-1 − 要求用户输入所需的字符。
第 2 步 - 显示菜单。
第 3 步 - 要求用户输入他们的选择。
Step-4 - 使用开关盒转到选择并执行操作。
第 5 步 - 打印结果。
让我们看看程序就可以清楚地理解它。
示例
import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner sc = new Scanner( System.in );
System.out.println("Enter a character to check if it's a Number, String or a Special character");
char ob1 = sc.next().charAt(0);
System.out.println("Now choose the operation you want to perform from the menu given below. ");
mainLoop: while (true) {
Scanner inn = new Scanner( System.in );
System.out.println("n***Menu***");
System.out.println("1. Check if a character is number");
System.out.println("2. Check if a character is String");
System.out.println("3. Check if a character is Special character");
System.out.println("4. Terminate the program");
System.out.println("Enter action number (1-4): ");
int command;
if ( inn.hasNextInt() ) {
command = inn.nextInt();
inn.nextLine();
}
else {
System.out.println("nILLEGAL RESPONSE. YOU MUST ENTER A NUMBER.");
inn.nextLine();
continue;
}
switch(command) {
case 1:
if (Character.isDigit(ob1)) {
System.out.println("Character is a number!");
} else {
System.out.println("Character is not a number!");
}
break;
case 2:
if (Character.isLetter(ob1)) {
System.out.println("Character is a String!");
} else {
System.out.println("Character is not a String!");
}
break;
case 3:
if (!Character.isDigit(ob1)
&& !Character.isLetter(ob1)
&& !Character.isWhitespace(ob1)) {
System.out.println("Character is a Special Character!");
} else {
System.out.println("Character is not a Special Character!");
}
break;
case 4:
System.out.println("Program terminated");
break mainLoop;
default:
System.out.println("Wrong choice!!");
}
}
}
}
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输出
Enter a character to check if it's a Number, String or a Special character
t
Now choose the operation you want to perform from the menu given below.
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
1
Character is not a number!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
3
Character is not a Special Character!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
2
Character is a String!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
$
ILLEGAL RESPONSE. YOU MUST ENTER A NUMBER.
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
1
Character is not a number!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
3
Character is not a Special Character!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
2
Character is a String!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
4
Program terminated
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在本文中，我们通过使用菜单驱动的方法，探讨了如何在Java中检查一个字符是否为字符串、数字或特殊字符。
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