Java TA

1. Java TA Session 1

2. Software • Java Runtime Environment (JRE) • java.exe • Java Development Kit (JDK) • java.exe, javac.exe • Version 1.6 = Version 6, Version 1.7 = Version 7 • Edit System Variables: • JAVA_HOME=C:\Program Files\Java\jdk1.6.0_32 • PATH=[…];C:\Program Files\Java\jdk1.6.0_32\bin • Editor: Notepad++, gedit

3. Java Startup • Open Test.java • Run javac: • C:\Users\user\Documents>javac Test.java • Run java: • C:\Users\user\Documents>java Test • Salam class Test { public static void main(String[] args) { System.out.println("Salam"); } }

4. Errors C:\Users\user\Documents>javac Add1.java Add1.java:3: cannot find symbol symbol : class Scanner location: class Add1 Scanner s = new Scanner(System.in); ^ Add1.java:3: cannot find symbol symbol : class Scanner location: class Add1 Scanner s = new Scanner(System.in); ^ 2 errors

5. Add Import statement import java.util.Scanner; class Add1 { public static void main(String[] args) { Scanner s = new Scanner(System.in); int a = s.nextInt(), b = s.nextInt(); int c = a+b; System.out.println("Sum is " + c); } }

6. What to Import? • You can read the Java API Specification at: • http://docs.oracle.com/javase/6/docs/api/ • Use search engines to find what you need: • For example you can use the following query to search for “scanner” in the Java 6 API, using google: scanner site:docs.oracle.com/javase/6/docs/api/

7. Functions • Use functions declared as public and static: public staticint sum(int x, int y) • Rewriting the previous code with a function: import java.util.Scanner; class Add1 { public static void main(String[] args) { Scanner s = new Scanner(System.in); int a = s.nextInt(); int b = s.nextInt(); int c = sum(a, b); System.out.println("Sum is " + c); } public static int sum(int x, int y) { return x+y; } }