Java String Class and Operations Quiz
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Questions and Answers

What is the implication of increasing the size of a matrix in terms of wastage space?

It will increase the wastage space.

In Java, what is a string?

In Java, string is basically an object that represents a sequence of char values.

How can you create a Java String object?

By string literal or by using the new keyword.

What is the difference between String and StringBuffer/StringBuilder classes in Java?

<p>String class is immutable while StringBuffer and StringBuilder classes are mutable.</p> Signup and view all the answers

How is a Java String literal created?

<p>By using double quotes.</p> Signup and view all the answers

What happens when a new Java String literal is created?

<p>The JVM checks the 'string constant pool' first.</p> Signup and view all the answers

What is the difference between creating a string using Java string literal and using the new keyword?

<p>Java string literal does not create a new instance if the value already exists in the string constant pool, while using the new keyword always creates a new object.</p> Signup and view all the answers

How does JVM handle string objects created using Java string literals and the new keyword?

<p>JVM creates a new string object in heap memory for new keyword usage, while it checks the string constant pool for literals and may return the reference if the value already exists.</p> Signup and view all the answers

What happens when a string object with a specific value is not found in the string constant pool?

<p>JVM creates a new object for that value in heap memory.</p> Signup and view all the answers

How can you create a string in Java using a character array?

<p>By using the constructor new String(char[] ch).</p> Signup and view all the answers

What is an algorithm?

<p>An algorithm is a step-by-step procedure or set of rules for solving a computational problem or performing a task.</p> Signup and view all the answers

How would you represent a sparse matrix in data structures?

<p>Sparse matrix can be represented efficiently using linked lists.</p> Signup and view all the answers

Define a sparse matrix.

<p>A matrix with a larger number of zero elements than non-zero elements.</p> Signup and view all the answers

How can non-zero elements in a sparse matrix be stored?

<p>Using triplets that represent rows, columns, and values.</p> Signup and view all the answers

What are the two ways to represent a sparse matrix?

<p>Array and LinkedList.</p> Signup and view all the answers

What are the three fields used in the 2D array representation of a sparse matrix?

<p>Row, Column, Value.</p> Signup and view all the answers

What is the purpose of Row field in a sparse matrix representation?

<p>To indicate the index of the row where a non-zero element is located.</p> Signup and view all the answers

How can a sparse matrix be visualized?

<p>As a grid with many zero elements and fewer non-zero elements.</p> Signup and view all the answers

Study Notes

Java Strings

  • A string in Java is an object that represents a sequence of characters.
  • An array of characters works similarly to a Java string.
  • Java String class provides various methods to perform operations on strings, such as compare(), concat(), equals(), split(), length(), replace(), compareTo(), intern(), and substring().
  • Java String is immutable, meaning it cannot be changed, and a new instance is created whenever a string is changed.
  • For mutable strings, StringBuffer and StringBuilder classes can be used.

Creating String Objects

  • There are two ways to create a String object: by string literal and by using the new keyword.
  • String literal is created by using double quotes, and the JVM checks the "string constant pool" first to avoid creating duplicate instances.
  • When creating a string using the new keyword, a new string object is created in the heap memory, and the literal is placed in the string constant pool.

String Example

  • The code snippet demonstrates creating strings using literals and the new keyword, and converting a char array to a string.

String Class Inbuilt Functions

  • Various inbuilt functions are available in the String class, such as length(), concat(), and substring(), among others.

Algorithm and Arrays

  • An algorithm is a step-by-step procedure for solving a computational problem or performing a task.
  • In Java, arrays can be declared using int[] Array or int Array[].
  • A 2D array can be declared as int mat[][] = new int.

2D Array - Matrix

  • A matrix can be defined as a 2D array having 'm' rows and 'n' columns.
  • A matrix with m rows and n columns is called an m × n matrix.

Sparse Matrix

  • A sparse matrix is a matrix that has a greater number of zero elements than non-zero elements.
  • The non-zero elements in a sparse matrix can be stored using triplets: rows, columns, and values.
  • There are two ways to represent a sparse matrix: array and linklist.
  • In 2D array representation, three fields are used: row, column, and value.

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Test your knowledge on Java String class and operations like compare, concat, split, length, replace, compareTo, and more. Understand how an array of characters works similarly to a Java string.

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