JAVA Menu Driven Program to Check Character is String, Number or Special Character

In this article, we will see a menu driven program to check if the entered character is number, string or special character by Java programming language. We will be implementing the application using a switch case.

To show you some instances 

Instance-1

Suppose the entered character is ?a? then the output should be "Entered character is a String".

Instance-2

Suppose the entered character is ?1? then the output should be "Entered character is a number".

Instance-3

Suppose the entered character is ?$? then the output should be "Entered character is a Special character".

Syntax

To check whether a character is String, Number or a Special character in Java we use isLetter, isDigit or isWhitespace functions. String is checked by isLetter function, Number is checked by isDigit function and special character is checked by combination of isLetter, isDigit and isWhitespace function.

Following is the syntax for String function

Character.isLetter(ob1)

Following is the syntax for number function

Character.isDigit(ob1)

Following is the syntax for String function

(!Character.isDigit(ob1)&& !Character.isLetter(ob1)&& !Character.isWhitespace(ob1))

Algorithm

Step-1 ? Ask the user to input the desired character.

Step-2 ? Display the menu.

Step-3 ? Ask the user to enter their choice.

Step-4 ? Use a switch case to go to the choice and perform the operation.

Step-5 ? Print the result.

Let?s see the program to understand it clearly.

Example

<div class="code-mirror  language-java" contenteditable="plaintext-only" spellcheck="false" style="outline: none; overflow-wrap: break-word; overflow-y: auto; white-space: pre-wrap;"><span class="token keyword">import</span> <span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token operator">*</span><span class="token punctuation">;</span>
<span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Main</span> <span class="token punctuation">{</span>
   <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span> args<span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token class-name">Scanner</span> sc <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Scanner</span><span class="token punctuation">(</span> <span class="token class-name">System</span><span class="token punctuation">.</span>in <span class="token punctuation">)</span><span class="token punctuation">;</span>
      <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Enter a character to check if it's a Number, String or a Special character"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
      <span class="token keyword">char</span> ob1 <span class="token operator">=</span> sc<span class="token punctuation">.</span><span class="token function">next</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">charAt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

      <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Now choose the operation you want to perform from the menu given below. "</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

      mainLoop<span class="token operator">:</span> <span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
         <span class="token class-name">Scanner</span> inn <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Scanner</span><span class="token punctuation">(</span> <span class="token class-name">System</span><span class="token punctuation">.</span>in <span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"\n***Menu***"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"1. Check if a character is number"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"2. Check if a character is String"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"3. Check if a character is Special character"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"4. Terminate the program"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Enter action number (1-4): "</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token keyword">int</span> command<span class="token punctuation">;</span>
         <span class="token keyword">if</span> <span class="token punctuation">(</span> inn<span class="token punctuation">.</span><span class="token function">hasNextInt</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token punctuation">{</span>
            command <span class="token operator">=</span> inn<span class="token punctuation">.</span><span class="token function">nextInt</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            inn<span class="token punctuation">.</span><span class="token function">nextLine</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token punctuation">}</span>
         <span class="token keyword">else</span> <span class="token punctuation">{</span>
            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"\nILLEGAL RESPONSE. YOU MUST ENTER A NUMBER."</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            inn<span class="token punctuation">.</span><span class="token function">nextLine</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token keyword">continue</span><span class="token punctuation">;</span>
         <span class="token punctuation">}</span>
         <span class="token keyword">switch</span><span class="token punctuation">(</span>command<span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">case</span> <span class="token number">1</span><span class="token operator">:</span>
            <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Character</span><span class="token punctuation">.</span><span class="token function">isDigit</span><span class="token punctuation">(</span>ob1<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is a number!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is not a number!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
            <span class="token keyword">break</span><span class="token punctuation">;</span>
            <span class="token keyword">case</span> <span class="token number">2</span><span class="token operator">:</span>
            <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Character</span><span class="token punctuation">.</span><span class="token function">isLetter</span><span class="token punctuation">(</span>ob1<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is a String!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is not a String!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
            <span class="token keyword">break</span><span class="token punctuation">;</span>
            <span class="token keyword">case</span> <span class="token number">3</span><span class="token operator">:</span>
            <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token class-name">Character</span><span class="token punctuation">.</span><span class="token function">isDigit</span><span class="token punctuation">(</span>ob1<span class="token punctuation">)</span>
            <span class="token operator">&&</span> <span class="token operator">!</span><span class="token class-name">Character</span><span class="token punctuation">.</span><span class="token function">isLetter</span><span class="token punctuation">(</span>ob1<span class="token punctuation">)</span>
            <span class="token operator">&&</span> <span class="token operator">!</span><span class="token class-name">Character</span><span class="token punctuation">.</span><span class="token function">isWhitespace</span><span class="token punctuation">(</span>ob1<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is a Special Character!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
               <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Character is not a Special Character!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
            <span class="token keyword">break</span><span class="token punctuation">;</span>
            <span class="token keyword">case</span> <span class="token number">4</span><span class="token operator">:</span>
            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Program terminated"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token keyword">break</span> mainLoop<span class="token punctuation">;</span>
            <span class="token keyword">default</span><span class="token operator">:</span>
            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"Wrong choice!!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token punctuation">}</span>

      <span class="token punctuation">}</span>

   <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</div>

Output

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

In this article, we explored how to check if a character is a string, number or special character in Java by using a menu driven approach.