Java Tutorial String Methods in Java

String Searching Methods in Java

StringBuilder Class in Java - GeeksforGeeks

String Best Practices in Java

Valid Parentheses in an Expression - GeeksforGeeks

JS Coding Question #10: Is Balanced Parenthesis [Very Common Question]

String Concatenation

Java String concat() Method with Examples - GeeksforGeeks

Java - Concatenate a string to the end of another string