A menu-driven program written in Java for performing basic string operations

String refers to a series of characters. In Java, String is an object. To create and manipulate strings, Java provides the String class. String class has many inbuilt methods which are used for different purposes.

We will perform a few basic string operations by using inbuilt String methods.

replace() Method: It replaces a specified character in the given string.
concat() Method: It appends another string to the end of one string.
length() Method: It returns the length of the given String.
Equals() Method: It checks whether two strings are equal or not.

In this article, we will learn some basic string operations, such as concatenating two strings, calculating string length, and comparing two strings using Java programming language. We will use switch case to implement the application.

Show you some examples−

The Chinese translation of

Instance-1

is:

Instance-1

Suppose the first String is ‘Java’ and the second String is ‘Python’ then by joining two String will give ‘JavaPython’. Here the concat() method will be used.

Instance-2

Suppose the first String is ‘Java’ and the second String is ‘Python’ then by counting two String will give its respective length as 4 and 6. Here length() method will be used.

Instance-3

Suppose the first String is ‘Java’ and the second String is ‘Python’ then by comparing two String will give “Both strings are not equal”. Here equals() method will be used.

Instance-4

is translated into Chinese as:

Instance-4

Assume the string is 'Java', replace the letter 'J' with 'R', then the new string will be Rava. The replace() method will be used here.

grammar

To perform basic string operations like joining the string, getting length of the string, comparing the string and replacing a specific value in a String we use concat(), length(), equals() and replace() methods respectively. The concat() method appends (concatenate) a string to the end of another string. The length() method returns the length of a specified string. The length of an empty string is 0. The equals() method compares two strings, and returns true if the strings are equal, and false if not. The replace() method replaces a specified value in a String with another new value .

The following is the syntax of "for loop" -

for (statement 1; statement 2; statement 3) {
   // code block to be executed
}

Following is the syntax for concat function

string1.concat(string2)

The following is the syntax of the length function

string1.length() 

Following is the syntax for equals function

string1.equals(string2)

The following is the syntax of the replace function

string1.replace(‘OldValue’, ‘NewValue’)

algorithm

Step-1 − Declare a String variable and initialize the value.

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 results.

Let's take a look at the program to understand it more clearly.

The Chinese translation of

Example

is:

Example

import java.util.*;
public class Main{
   public static void main(String args[]){
      System.out.println("First String");
      String s1 = "Hello";
      System.out.println("Second String");
      String s2 = "World";
      mainLoop: while (true) {
         Scanner inn = new Scanner( System.in );
         System.out.println("\n***Menu***");
         System.out.println("1. Join Two Strings");
         System.out.println("2. Get length of a String");
         System.out.println("3. Compare two Strings");
         System.out.println("4. Replace a value in String");
         System.out.println("5. Terminate the program");
         System.out.println("Enter action number (1-5): ");
         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:
               String joinedString = s1.concat(s2);
               System.out.println("Joined String: " + joinedString);
               break;
            case 2:
               int length1 = s1.length();
               System.out.println("Length of first String: " + length1);
               int length2 = s2.length();
               System.out.println("Length of second String: " + length2);
               break;
            case 3:
               boolean result = s1.equals(s2);
            if(result == true) {
               System.out.println("Strings first and second are equal");
            }
            else{
               System.out.println("Strings first and second are not equal");
            }
            break;
            case 4:
               String newString = s2.replace('W', 'Z');
               System.out.println("After replacing the new string is: "+newString);
               break;
            case 5:
               System.out.println("Program terminated");
               break mainLoop;
            default:
               System.out.println("Wrong choice!!");

         }
      }
   }
}

Output

First String
Second String

***Menu***
1. Join Two Strings
2. Get length of a String
3. Compare two Strings
4. Replace a value in String
5. Terminate the program
Enter action number (1-5):
2
Length of first String: 5
Length of second String: 5

***Menu***
1. Join Two Strings
2. Get length of a String
3. Compare two Strings
4. Replace a value in String
5. Terminate the program
Enter action number (1-5):
1
Joined String: HelloWorld

***Menu***
1. Join Two Strings
2. Get length of a String
3. Compare two Strings
4. Replace a value in String
5. Terminate the program
Enter action number (1-5):
4
After replacing the new string is: Zorld

***Menu***
1. Join Two Strings
2. Get length of a String
3. Compare two Strings
4. Replace a value in String
5. Terminate the program
Enter action number (1-5):
3
Strings first and second are not equal

***Menu***
1. Join Two Strings
2. Get length of a String
3. Compare two Strings
4. Replace a value in String
5. Terminate the program
Enter action number (1-5):
5
Program terminated

In this article, we explored how to perform simple string operations in Java by using a menu-driven approach.

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