Java: Check if a given string is a mathematical expression

Last update on May 24 2025 12:59:24 (UTC/GMT +8 hours)

29. Check Mathematical Expression

Write a Java program to check if a given string is a mathematical expression or not.

Sample Solution:

Java Code:

public class test { 
   public static void main(String[] args) {	   
	    String text = "10";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = "10 + 20";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = " 10 * 20 * 30 ";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = "-10 * 20 - -30";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = "-10 * 20 - -2e4";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = "100 +";
		System.out.println("\nOriginal string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = "100 + foo";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
		text = " 10 *+ 20 * 30 ";
		System.out.println("Original string: "+text);
		System.out.println("Check if the said string is a mathematical expression or not: "+validate(text));
        }

   public static boolean validate(String text) {
	   return text.matches("((?:(?:^|[-+_*/])(?:\\s*-?\\d+(\\.\\d+)?(?:[eE][+-]?\\d+)?\\s*))+$)");
    }
}

Sample Output:

Original string: 10
Check if the said string is a mathematical expression or not: true
Original string: 10 + 20
Check if the said string is a mathematical expression or not: true
Original string:  10 * 20 * 30 
Check if the said string is a mathematical expression or not: true
Original string: -10 * 20 - -30
Check if the said string is a mathematical expression or not: true
Original string: -10 * 20 - -2e4
Check if the said string is a mathematical expression or not: true

Original string: 100 +
Check if the said string is a mathematical expression or not: false
Original string: 100 + foo
Check if the said string is a mathematical expression or not: false
Original string:  10 *+ 20 * 30 
Check if the said string is a mathematical expression or not: false

Flowchart :

For more Practice: Solve these Related Problems:

• Write a Java program to verify if a string represents a valid mathematical expression using regex and operator precedence checks.
• Write a Java program to check if a string contains only numbers, arithmetic operators, and valid parentheses.
• Write a Java program to implement a method that returns true if the input string is a properly formatted mathematical formula.
• Write a Java program to validate a mathematical expression by ensuring operands and operators are in a correct sequence.

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