JAVA ile Programciliga Giris 1.2.2

1. JAVA ile Programciliga Giris 1.2.2

2. Storing charactersHarfleri Depolamak Variables of type char store a single character code. char myCharacter = ‘X’; Character Escape Sequences char myCharacter = ‘\u0058’; System.out.println(“\”It\’s freezing in here\”, he said coldly.”); \b Backspace \f Form feed \n New line \r Carriage return \t Tab

3. Character Arithmetic Harf aritmetigi Character arithmetic myCharacter += 1; // Increment to next character ++myCharacter; // Increment to next character char aChar = 0; char bChar = ‘\u0028’; aChar = (char)(2*bChar + 8); Here are the hexadecimal codes for the letters: A: 41 B: 42 C: 43

4. Storing charactersHarfleri Depolamak EXAMPLE- Arithmetic with Character Codes – CHARCODECALCS public class CharCodeCalcs { public static void main(String[] args){ char letter1 = ‘A’; // letter1 is ‘A’ char letter2 = (char)(letter1+1); // letter2 is ‘B’ char letter3 = letter2; // letter3 is also ‘B’ System.out.println(“Here\’s a sequence of letters: “+ letter1 + letter2 + (++letter3)); // letter3 is now ‘C’ System.out.println(“Here are the decimal codes for the letters:\n”+ letter1 + “: “ + (int)letter1 + “ “ + letter2 + “: “ + (int)letter2 + “ “ + letter3 + “: “ + (int)letter3); } } import static java.lang.Integer.toHexString;

5. Bitwise OperationsBit Islemleri & AND , | OR ^ Exclusive OR if both bits are the same the result is 0; otherwise, the result is 1. ~ Complement it inverts all the bits, so that each 1 bit becomes 0, and each 0 bit becomes 1 Using the AND OR Operators thirdBit = indicators & 0x4; // Select the 3rd bit

6. Bitwise OperationsBit Islemleri EXAMPLE- Bitwise AND and OR operations-BITWISEOPS import static java.lang.Integer.toBinaryString; public class BitwiseOps { public static void main(String[] args) { int indicators = 0xFF07; int selectBit3 = 0x4; // Mask to select the 3rd bit // Try the bitwise AND to select the third bit in indicators System.out.println(“indicators = “ + toBinaryString(indicators)); System.out.println(“selectBit3 = “ + toBinaryString(selectBit3)); indicators &= selectBit3; System.out.println(“indicators & selectBit3 = “ + toBinaryString(indicators)); // Try the bitwise OR to switch the third bit on indicators = 0xFF09; System.out.println(“\nindicators = “+ toBinaryString(indicators)); System.out.println(“selectBit3 = “+ toBinaryString(selectBit3)); indicators |= selectBit3; System.out.println(“indicators | selectBit3 = “ + toBinaryString(indicators)); // Now switch the third bit off again indicators &= ~selectBit3; System.out.println(“\nThe third bit in the previous value of indicators” + “ has been switched off”); System.out.println(“indicators & ~selectBit3 = “ + toBinaryString(indicators)); } }

7. Bitwise OperationsBit Islemleri Using the Exclusive OR operator a ^= b; byte allBitsOne = 0xFF; // Wrong!! byte allBitsOne = 0xFFFFFFFF; // Correct – well done!! Shift Operations << Shift left, filling with zeros from the right. >> Shift right, propagating the sign bit from the left. >>> Shift right, filling with zeros from the left.

8. Bitwise OperationsBit Islemleri EXAMPLE-Using shift Operations-PACKING CHARACTERS import static java.lang.Long.toHexString; public class PackingCharacters { public static void main(String[] args) { char letterA = ‘A’; char letterB = ‘B’; char letterC = ‘C’; char letterD = ‘D’; long packed = 0L; packed = letterD; // Store D packed = (packed << 16) | letterC; // Shift and add the next letter - C packed = (packed << 16) | letterB; // Shift and add the next letter - B packed = (packed << 16) | letterA; // Shift and add the next letter - A System.out.println(“packed now contains 0x” + toHexString(packed)); // Now unpack the letters and output them long mask = 0xFFFF; // Rightmost 16 bits as 1 char letter = (char)(packed & mask); // Extract the rightmost letter System.out.println(“From right to left the letters in packed are:”); System.out.println(“ “ + letter + “ 0x” + toHexString(letter)); packed >>= 16; // Shift out the rightmost letter letter = (char)(packed & mask); // Extract the new rightmost letter System.out.println(“ “ + letter + “ 0x” + toHexString(letter)); packed >>= 16; // Shift out the rightmost letter letter = (char)(packed & mask); // Extract the new rightmost letter System.out.println(“ “ + letter + “ 0x” + toHexString(letter)); packed >>= 16; // Shift out the rightmost letter letter = (char)(packed & mask); // Extract the new rightmost letter System.out.println(“ “ + letter + “ 0x” + toHexString(letter)); } }

9. Bitwise OperationsBit Islemleri Methods for Bitwise operations bitCount(arg) highestOneBit(arg) lowestOneBit(arg) numberOfLeadingZeros(arg) int data = 0x0F00; // data is: 0000 0000 0000 0000 0000 1111 0000 0000 int bits = Integer.bitCount(data); // Result is 4

10. Bitwise Operations EXAMPLE- Methods for Bitwise operations-TRYBITMETHODS import static java.lang.Long.*; public class TryBitMethods { public static void main(String[] args) { long number = 0xF00000000000000FL; System.out.println(“number:\n” + toBinaryString(number)); long result = rotateLeft(number,2); System.out.println(“number rotated left 2 bits:\n” + toBinaryString(result)); result = rotateRight(number, 3); System.out.println(“number rotated right 3 bits:\n” + toBinaryString(result)); result = reverse(result); System.out.println(“Previous result reversed:\n” + toBinaryString(result)); System.out.println(“Bit count in number:\n” + bitCount(number)); } } 76

11. enumeration Variables with a fixed set of integer values You will often need variables that can have values only from a predefined fixed set. enum Day {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday } Day weekday = Day.Tuesday;

12. enumeration Variables with a fixed set of integer values enum Month { January, February, March , April , May , June, July , August , September, October, November, December } Month current = Month.September; // Initialize to September current = Month.October;

13. enumeration EXAMPLE-Using enumeration- TRYENUMERATION public class TryEnumeration { // Define an enumeration type for days of the week enum Day {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday } public static void main(String[] args) { // Define three variables of type Day Day yesterday = Day.Thursday; Day today = Day.Friday; Day tomorrow = Day.Saturday; // Output the values of the Day variables System.out.println(“Today is “ + today); System.out.println(“Tomorrow will be “ + tomorrow); System.out.println(“Yesterday was “ + yesterday); } }

14. Boolean variablesBool Degiskenleri Variables of type boolean can have only one of two values, true or false. The values true and false are boolean literals boolean state = true; state = false;

15. Operator precedenceIslem Önceligi a = b + c + 10; a = (b + c) + 10; (), [], postfix ++, postfix -- unary +, unary -, prefix ++, prefix --, ~, ! (type), new *, /, % +, - <<, >>, >>> < ,<= , >, >=, instanceof ==, != & ^ | && || =, +=, -=, *=, /=, %=, <<=, >>=, >>>=, &=, |=, ^=

16. comments Yorumlar Program comments /*************************************** * This is a long explanation of * * some particularly important * * aspect of program operation. * ***************************************/ Documentation Comments /** This is a documentation comment. */ //single line comment