password = con.readPassword("Enter your password: "); Exception in thread "main" java.lang.ArithmeticException: / by zero, Exception in thread "main" java.util.IllegalFormatConversionException: d != java.lang.Double. For examples. You can refer to an element of an array via an index (or subscript) enclosed within the square bracket [ ]. // Return circle's area given its radius, // Return maximum among two given integers, /** Example of Java Method definition and invocation */, // The max() method returns the maximum of two given int, // The min() method returns the minimum of two given int, // Increment each of the element of the given int array, // int 8 autocast to double 8.0, invoke version 3, // error - float[] is not casted to double[], // Generate a random int between 0 and 99, // find the nearest integral square root of x, // a factor found, no need to find more factors, // To test whether int x is a perfect number, // Change the value of a and b: a b, b a mod b, and repeat until b is 0, // after the loop completes, i.e., b is 0, we have GCD(a, 0), Introduction To Java Programming for First-time Programmers, Data Representation - Integers, Floating-Point Numbers and Characters,,, Code Convention for the Java Programming Language,,,, 32-bit single precision floating-point number, 64-bit double precision floating-point number, Double-quote (Needed to be used inside double-quoted, Single-quote (Needed to be used inside single-quoted, Back-slash (Needed as back-slash is given a special meaning), Compound modulus (remainder) and assignment, Right-shift and padded with sign bit (signed-extended right-shift), Right-shift and padded with zeros (unsigned-extended right-shift), An identifier is a sequence of characters, of any length, comprising uppercase and lowercase letters, White space (blank, tab, newline) and other special characters (such as. // byte, short, int, What is the output of the below Java code with a FOR loop? If you define a method that takes a varargs. That is, multiple contiguous white spaces are treated as a single white space. Again, Java runtime does NOT issue an error/warning message, but produces an imprecise result. You can use an int, byte, short, or char variable as the case-selector, but NOT long, float, double and boolean. Repeat the process until the second term is 0. In Java, '+' is a special operator. // variable declaration The first word is in lowercase, while the remaining words are initial-capitalized. Integer operations are straight-forward. Furthermore, you MUST know the type of a value before you can interpret a value. d) reference Does Java regard a 'normal' space as whitespace for the purposes of Character.isWhitespace? For example, MIN_VALUE, MAX_SIZE, and INTEREST_RATE_6_MTH. The RHS shall be a literal value or an expression that evaluates to a value; while the LHS must be a variable. The for-each loop is handy to transverse all the elements of an array. (A) Ability to run the Byte on different machines producing the same behavior and output, (B) Java does not actually provide portability, (C) Generating suitable Byte Code for each machine by the Compiler, (D) Small code size easy to carry occupying less disk space. You can also express them in scientific notation, e.g., 1.2e3, -5.5E-6, where e or E denotes the exponent in base of 10. The assignment statement should be interpreted this way: The expression on the RHS is first evaluated to produce a resultant value (called r-value or right-value). Refer to JDK Documentation for the detailed descriptions (@ for JDK 10). You are also permitted to use underscore (_) to break the digits into groups to improve the readability. A positive integer is called a perfect number if the sum of all its proper divisor is equal to its value. 132- We can create a thread in Java by ?? Identify the data types and name the variables. The syntax is: Suppose that you need a method to perform certain actions (e.g., printing) without a need to return a value to the caller, you can declare its return-value type as void. Is it against the law to sell Bitcoin at a flea market? Choose good names that are self-descriptive and meaningful, e.g.. For example, 1/2 0 (int), but 1.0/2.0 0.5 (double / double double). */, // floating-point numbers are NOT precise, // Set a threshold for comparison with ==, // int + double double + double double, // char + int int + int int (need to cast back to char '2'), // Value of "sum" converted to String and concatenated, // Only one statement in the block, can omit { }, // More than one statements in the block, need { }, // This else-block contains a if-else statement, // This else-block also contains a if-else statement. Inside the method body, you could use a return statement to return a value (of the returnValueType declared in the method's signature) to return a value back to the caller. To assign the a double value to an int variable, you need to invoke the so-called type-casting operator - in the form of (int)doubleOperand - to operate on the double operand and return a truncated value in int. By closing this banner, scrolling this page, clicking a link or continuing to browse otherwise, you agree to our Privacy Policy, Explore 1000+ varieties of Mock tests View more, Special Offer - Free Java Online Course Learn More, 4+ Hours | Lifetime Access | Verifiable Certificates, Java Training (41 Courses, 29 Projects, 4 Quizzes), JavaScript Training Program (39 Courses, 23 Projects, 4 Quizzes), jQuery Training (8 Courses, 5 Projects), Java Interview Question on Multithreading, Multithreading Interview Questions in Java, Software Development Course - All in One Bundle, Null is one of the literals in Java. Name of a Class, Variable, Method or an Interface in Java language is called? To run the above program, create a text file called in.txt containing: Java SE 5.0 also introduced a so-called Formatter for formatted output (just like Scanner for formatted input). Blamed in front of coworkers for "skipping hierarchy". During program development, instead of deleting a chunk of statements irrevocably, you could comment-out these statements so that you could get them back later, if needed. (A) When it makes sense to have objects of that class, (B) When it doesnt make sense to have objects of that class. Java does not have an exponent operator. A do-while loop with a boolean flag could be more appropriate as it prompts for input at least once, and repeat again and again if the input is invalid. To check for arithmetic overflow (known as secure coding) is tedious. // Try mark = 81, which only run thru only the first if. To program in Java, you MUST read the ". (D) To prevent developers from further extending the class. // This "nested-if" is the BEST with fewer tests, // Selector Types: A variable declaration statement begins with a. Comment your code liberally. int main = 13; 37- In a .java file, how many numbers of public types namely class or interface or abstract can be managed ?? c) Documentation comment Need suffix 'f' for float. If BOTH operands are int, long, float or double, the binary arithmetic operations are carried in that type, and evaluate to a value of that type, i.e.. The following diagram shows the order of implicit type-casting performed by compiler. I will explain them in due course. As already mentioned, if multiple words are used, then CamelCase has to be followed. For examples. The commonly-used escape sequences are: A String is a sequence of characters. }. For example. In programming, the following arithmetic expression: must be written as (1+2*a)/3 + (4*(b+c)*(5-d-e))/f - 6*(7/g+h).

* List all non-prime numbers between 2 and an upperbound All the statements inside the block is treated as one single unit. (MUST READ) "Code Conventions for the Java Programming Language" @. On the other hand, for the while-loop, the index variable number is available inside and outside the loop. 90- In Java which method cannot be overridden ? In other words, for each reference to an array element, the index is checked against the array's length. In Java how does one turn a String into a char or a char into a String?

For example, the following one-line hello-world program works. It works for simple toy program, but it is neither effective nor efficient for complex program. // "marks" is assigned to a special value called "null" before allocation, // Same as above, but the above syntax recommended, // Allocate 5 elements via the "new" operator, // Declare and allocate a 20-element array in one statement via "new" operator, // Declare, allocate a 6-element array thru initialization, // size of array deduced from the number of items, // Declare & allocate a 5-element int array, // Declare and allocate a 5-element int array, /** For example. To swap the values of two variables, we need to define a temporary variable as follows: Let us look into the Euclidean algorithm, GCD(a, b) = a, if b is 0. You need to use a white space to separate two keywords or tokens to avoid ambiguity, e.g.. Java, like most of the programming languages, ignores extra white spaces.

* Print the minimum, maximum and bit-length of all primitive types (except boolean) Again, there are a few types of loops: for, while-do, and do-while. However, proper indentation (with tabs and blanks) and extra empty lines greatly improves the readability of the program. Attempt a small test to analyze your preparation level. The binary AND (&&) and OR (||) operators are known as short-circuit operators, meaning that the right-operand will not be evaluated if the result can be determined by the left-operand. Instead, you need to break out the two binary comparison operations x > 1, x < 100, and join with a logical AND operator, i.e., (x > 1) && (x < 100), where && denotes AND operator. a) Single-line comment JDK 5 provides an built-in methods called Arrays.toString(anArray), which returns a String in the form [a0, a1, , an]. You can add a label to a loop in the form of labelName: loop. 150- Which is a type of Integer literals in Java ?? A conditional operator is a ternary (3-operand) operator, in the form of booleanExpr ? What will happen? Compute their sum in "int" The is defaulted to be the keyboard; while System.out and System.err are defaulted to the display console. // You can assign an integer in the range of [0, 65535] to char, // 'b' printed instead of the number, because the type is char, // Since back-slash is given a special meaning, This is because both the sum and 100 are int. They are represented differently in the computer memory, with different precision and interpretation. What are kinds of whitespaces in Java? On the other hand, integer division produces a truncated integer and results in so-called underflow. /** Compute the average of running numbers 1 to 100 */, // Won't work (average = 50.0 instead of 50.5), // Cast sum from int to double before division, double / int -> double / double -> double, // Cast 100 from int to double before division, int / double -> double / double -> double, // int / double -> double / double -> double, // byte + byte -> int + int -> int, need to explicitly cast back to "byte", // char + int -> int + int -> int, need to explicitly cast back to "char", // Two operations in the statement: increment and assignment, // Increment x (=6), then assign x to y (=6). The precedence from highest to lowest is: '!' It performs a piece of programming action. Program testing is beyond the scope of this writing. Why don't you check if text.trim() has a different length? */, // Set up the secret number: Math.random() generates a double in [0.0, 1.0), // Use a while-loop to repeatedly guess the number until it is correct, // Construct a Scanner to scan a text file, // Use the same set of methods to read from the file, /** This is because: In Java, you will get a compilation "error: incompatible types: possible lossy conversion from double|float|long to int" if you try to assign a double, float, or long value of to an int variable. (++x returns x+1), // Assign x to y (=5), then increment x (=6). // Cannot write "intsum". In a switch-case statement, a break statement is needed for each of the cases. Trace program execution step-by-step and watch the value of variables and outputs. //Java program with an identifier that starts with $ This is known as "command-line arguments", which corresponds to the augments provided by the user when the java program is invoked. */.

The program shall calculate the income tax payable (in double); and print the result rounded to 2 decimal places. A valid identifier in Java language may contain which characters? By using our site, you \s A whitespace character: [ \t\n\x0B\f\r]. (There are other structures that can be dynamically adjusted.). // variable declaration You can process all the elements of an array via a loop, for example. An identifier is needed to name a variable (or any other entity such as a method or a class). For boolean method, you can simply return the resultant boolean value of the comparison, instead of using a conditional statement, as follow: JDK provides many common-used Mathematical methods in a class called Math. Choose a multiline comment in Java language below? // Input to Integer.parseInt() must be a valid integer literal, // Input to Integer.parseInt() must be a valid double literal, // Using String concatenation operator '+' with an empty String (applicable to ALL primitive types), // Using toString() for each primitive type, // Returns a String "1.2" (for further operations), // Declare an int array named "marks" 35- In Java programming, an Interface or Abstract Class is kept in which file after compilation ?? 25- How many primitive data types are available in the Java programming language ?? Using this pattern in a regex, we can either replace consecutive whitespace with a single space or remove all whitespace from the input string. 1- Who developed/invented the Java language ?? public class JavaIdentifierExampl { In Java, chars are represented using 16-bit Unicode. It is important to take note int division produces an int, i.e., int / int int, with the result truncated. This is known as pass-by-value. }. 147- Decrement operator in Java decreases the value of a variable by what number ?? 127- What is the range of byte data type in Java ?? (A) When many classes inherit from one super class, (B) When one class inherits from more super classes, (C) More classes inherit from more super classes. /** It is important to note that checking array index-bound consumes computation power, which inevitably slows down the processing. Read "Type-Casting" on the conversion rules. 2011-2022 Sanfoundry. Or you can leave the loop with break; after containsWhitespace was set to true. }. It is invalid to write 1 < x < 100 (non-binary operations). (A) An abstract class can be used as a data type, (B) A subclass of a non-abstract superclass can be abstract. You can use con.printf() for formatted output with format specifiers such as %d, %s. Provide comments in your program! Print the result It is \u000B, U+000B VERTICAL TABULATION. How to generate java class files in a project? If the index is outside the range of [0, arrayName.length-1], Java Runtime will signal an exception called ArrayIndexOutOfBoundException. 6- In which year Java was first released ?? Statement: A programming statement is the smallest independent unit in a program, just like a sentence in the English language. Return value: This method returns true if the character is a Java whitespace character, false otherwise. A directory of Objective Type Questions covering all the Computer Science subjects. The coding pattern for printing 2D patterns is as follows. 95- Which of the following is the correct way to declare an abstract method in an abstract Java class ?? Suppose that we wish to write a method called isOdd() to check if a given number is odd. This is extremely important for others (and yourself three days later) to understand your programs. View Answer. Suppose a program defines a keyword as an identifier, as shown below, and we are trying to compile it. An expression is a combination of operators (such as '+' and '-') and operands (variables or literals), that can be evaluated to yield a single value of a certain type. Write an expression for all unmarried male, age between 21 and 35, with height above 180, and weight between 70 and 80. 2022 - EDUCBA. For example. You could use Double.parseDouble(aDoubleStr) or Float.parseFloat(aFloatStr) to convert a String (containing a floating-point literal) into a double or float, e.g. For positive integers, the magnitude is the same as the binary number, e.g., if n=16 (short), 0000000000000010 is +210. (A) JIT Compiler assists the actual JAVAC compiler to compile fast, (B) JIT Compiler produces Byte Code from Java file, (D) JIT Compiler takes chunks of Byte Code as input and produces Executable code on that particular machine. The most commonly-used String methods are as follows, suppose that str, str1, str2 are String variables: To check all the available methods for String, open JDK Documentation Select "API documentation" Click "FRAMES" (top menu) From "Modules" (top-left pane), select "java.base" From "java.base Packages" (top-left pane), select "java.lang" From "Classes" (bottom-left pane), select "String" choose "SUMMARY" "METHOD" (right pane) (@ for JDK 10). 36- A public class or an abstract class or interface must be kept in a separate .java file ?? There are three basic flow control constructs - sequential, conditional (or decision), and loop (or iteration), as illustrated below. It then print the histogram, in horizontal and vertical forms, as follows: The following program prompts user for a hexadecimal string and convert it to its binary equivalence. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. A String literal is composed of zero of more characters surrounded by a pair of double quotes. 21- All Transcendental math functions return the value of which data type ??

public class JavaIdentifierExampl { Since all the Java's integers (byte, short, int and long) are signed integers, left-shift << and right-shift >> operators perform signed-extended bit shift. Heres the list of Best Books in Object Oriented System Design. 109- The valid White Spaces available in Java is/are ?? 66- Which of these currently owns JAVA language and has its copyrights ? Also hard to read, /** 142- The IEEE standard adopted to represent Java Floating-Point Numbers is ? For example, the maximum, minimum and bit-size of int are kept in built-in constants INTEGER.MIN_VALUE, INTEGER.MAX_VALUE, INTEGER.SIZE. A valid Identifier or name in Java language can start with which character? acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Character.isIdentifierIgnorable() in Java with Examples, Character.isWhitespace() method in Java with examples. Indentation: Indent each level of the body of a block by an extra 3 or 4 spaces according to the hierarchy of the block. For example, use an integer type for counting and whole number; a floating-point type for number with fractional part, String for text message, char for a single character, and boolean for binary outcomes. For example. /** Print the values rounded to 2 decimal places. The system shall maintain information about students. 92- A Java language method is like a function in C language ?? JDK 5 introduces variable arguments (or varargs) and a new syntax "Type". We use two arrays in this exercise, one for storing the grades of the students (of the length, We keep the binary string corresponding to hex digit, We use modulus/divide algorithm to get the hex digits (. At times, a certain portion of code has to be used many times. boolean value cannot be type-casted (i.e., converted to non-boolean). In Java, identifiers are considered as a sequence of 1 or more than 1 character that helps in naming variables, methods, classes, etc.

94- For standalone Java applications, what is the necessary method ?? 102- For an abstract class in Java what is true ?? 143- The character encoding standard used in Java language is ?? rev2022.7.21.42639. A character is called a whitespace character in Java if and only if Character.isWhitespace(char) method returns true. It is better to ask the computer to check for overflow/underflow (if you design a new language), because few humans expect such results. 93- The purpose to put static keyword before the main method is ?? Take note that printf() does not advance the cursor to the next line after printing. // Set gameOver to true if appropriate to exit the game loop, // exit the loop upon the next iteration test, // prompt user to enter an int between 1 and 10, // if the number entered is valid, set done to exit the loop, // Print error message and repeat (isValid remains false). It can be assigned directly to a variable; or used as part of an expression. Below programs illustrate the Character.isWhitespace(char ch) method: Program 3: When the parameter is of type int. Nonetheless, you need to estimate the length and allocate an upper bound. Not ALL numbers can be represented using a finite precision (32-bit float or 64-bit double). 24- What type of language Java is among these ?? The following program can be used to print the maximum, minimum and bit-length of the primitive types. It is estimated that over the lifetime of a program, 20 percent of the effort will go into the original creation and testing of the code, and 80 percent of the effort will go into the subsequent maintenance and enhancement. There should be no space or other characters in the number. } Hence, grid.length gives 12 and grid[0].length gives 8. 85- In Java, what can evaluate any type of Boolean expression ?? * 4. //for each iteration, // num = 1, 2, 3, , n for each iteration, // Need a semi-colon to Bitwise operators perform operations on one or two operands on a bit-by-bit basis, as follows, in descending order of precedences. There are a few types of conditionals, if-then, if-then-else, nested-if, switch-case-default, and conditional expression. //Java program with an identifier which do not have any whitespace * List all prime numbers between 2 and an upperbound Your program typically contains data of many types, e.g., count and sum are int, average and gpa are double, and message is a String.