1. 1 Printing characters : Revisited class printcharacter{ public static void main(String arg[]){ char grade=‘A’; System.out.println(grade);// prints A System.out.println((int)grade); // prints 65 System.out.println(grade+’B’);// prints 131 System.out.println(grade+1);// prints 66 System.out.println(grade+"1");// prints A1 System.out.println(grade+'1');// prints 114 System.out.println((char)(grade+1));// prints B } Notice the difference between 1, ‘1’ and “1” Notice the automatic type conversion with + operator

2. 2 Java Built-in Primitive Data Types TypeMeaning booleanTrue/False charCharacter byte8-bit integer (-128 to +127) short16-bit integer (-32768 to 32767) int32-bit integer (-2147483648 to 2147483647 long64-bit integer (-9223372036854775808 to 9223372036854775807 float32-bit floating point number Range: [+ or - (3.40282347E+38 to 1.40239846E-45)] double64-bit (double-precision) floating point number Note: double can be assigned to long but long cannot be assigned to double

3. 3 Logical operators Not: ! AND: && OR: || Examples: int x = 12; boolean isTwoDigit = ((x >= 10) && (x < 100)); boolean isMultipleOfSix = ((x%6)==0); boolean isOdd = !((x%2)==0); boolean isTwoDigit = (10 <= x < 100); [Wrong!]

4. 4 Checking case class upperCaseCharacter{ public static void main(String arg[]){ char c=‘0’; boolean isuppercase, islowercase; isuppercase = ((c >= ‘A’) && (c <= ‘Z’)); islowercase = ((c >= ‘a’) && (c <= ‘z’)); System.out.ptintln(“The character is ” + c + “. Uppercase: ” + isuppercase); }

5. 5 Divisibility by 4 class divisibleByFour{ public static void main(String arg[]){ int x = 121; int lastTwoDigits; boolean isdivBy4; lastTwoDigits = x%100; isdivBy4 = ((lastTwoDigits % 4) == 0); System.out.println(“The number is: ” + x + “. Divisible by 4? ” + isdivBy4); }

6. 6 Exchanging numbers class swapBad{ public static void main(String arg[]){ int x = 121; int y = 200; System.out.println(“x: ” + x + “, y: ” + y); x = x + y;// Could overflow y = x – y; x = x – y; System.out.println(“x: ” + x + “, y: ” + y); }

7. 7 Exchanging numbers class swapGood{ public static void main(String arg[]){ int x = 121; int y = 200; int temp; System.out.println(“x: ” + x + “, y: ” + y); temp = x; x = y; y = temp; System.out.println(“x: ” + x + “, y: ” + y); }

8. 8 Operator precedence Higher to lower precedence ++, -- (both post and pre) !(logical NOT) *, /, %(multiply, divide, mod) +, -(add, subtract), >=(LT, LE, GT, GE) ==, !=(equality and non-equality) &&(logical AND) ||(logical OR) =(assignment)

9. 9 Operator precedence What is the answer? (assume x=1) x*x+x%2 2*x/2%4(need to know associativity) Almost all operators are left associative –This indicates in which direction the operators of the same precedence will evaluate –Assignment has right associativity x=y=2;// assigns y=2 first and then x=y –The above expression would lead to wrong answer if assignment was left associative