Java notes

Final and Finally:
//Final variable can not be changes
//Finally is a block in try catch clock
//Throw: deliberately throwing exception- your own description-uncaught exception
//when we deliberately throw?? suppose we have 4 tests..1 st test to run 2nd no run , here we deliberately throw exception
//Throws -capable of throwing an exception

//Finally is always executed whether or not the try catch block is success or not
//Throw able is super class-under this exception and error..and there is one more called, run time exception
//so we use catch(throw able) in that case- any type of error or exception

try{
//establish connection and get results and close connection, to close connection always use finally

//int i=8/0;
return;
}
catch(Exception e){
System.out.println("error");
}
finally{
System.out.println("close");

Collection API's:

//i want to store all links on a page into an array, the no.of links may change when i refresh my page
//i don't know the final size of array

//array list used to create dynamically growing list of array
ArrayList<String> list = new ArrayList<String>();

list.add("A");//0
list.add("B");//1

//list.add(667) //we get errpr as it is string type

//we get some warniing symbol if we do list.add("A")
//we need to give which type of array<string>

System.out.println(list.get(1));
for (int i=0;i<list.size();i++)
System.out.println(list.get(i));

//hash table//Hash table table= new Hash table();
//hash table is another type for dynamically growing list
//hash table use key and value concept
//hash table doesn't have index

Hashtable<String,String> table=new Hashtable<String,String>();
table.put("name","meeraja");
table.put("place","ca");
System.out.println(table.get("place"));// will print ca
table.put("place","san ramon");
System.out.println(table.get("place"));  will print san ramon


Properties file:
//create properties file with various fields for the use of selenium
//we can store x paths
//it is similar to Object repository
//to keep all the x paths of files, check boxes etc
//get this properties file by using its path by right click and select  properties

name=meeraja

age=34

hobbies=cooking

dob=oct 18

public class ReadingProperties {

public static void main(String[] args) throws IOException {

Properties prop= new Properties();

FileInputStream fs= new FileInputStream("C:\\eclipse-workspace-meeraja\\Test\\src\\config\\Employee.properties");

//FileInputStream fs1=  new FileInputStream(System.getProperty("user.dir" ) + "\\src\\config\\Employee.properties");

prop.load(fs);

//properties is a inbuilt class...

Reading File:

//create file

File f=new File("c:\\meeraja-Selenium\\temp.txt");

f.createNewFile();

//write into file

FileWriter w=new FileWriter("c:\\meeraja-Selenium\\temp.txt");

BufferedWriter bf= new BufferedWriter(w);

bf.write("first line");

bf.newLine();

bf.write("first line");

bf.flush();

//read file

FileReader r=new FileReader("c:\\meeraja-Selenium\\temp.txt");

BufferedReader br= new BufferedReader(r);

String x="";

while((x=br.readLine()) !=null)

{

System.out.println(x);

}

String functions:

String str="My name is padmaja";

String str1="My name is rama";

System.out.println("length is " +str.length());

System.out.println("char is " +str.charAt(5));

System.out.println("index is " +str.indexOf('m'));//first occurance is at 5 

System.out.println("index is " +str.indexOf('m',6));// index of functiom ith letter and index from there i.e.after 5 so, give 6

System.out.println(str.indexOf("hello")); //will print -1

System.out.println(str.equals(str1));  //will print false

System.out.println(str.substring(3, 10));  //will print 'name is'

//String temp[]=str.split("name");

String temp[]=str.split(" ");

for(int i=0;i<temp.length;i++)

System.out.println(temp[i]);  //print each word in separate line

String z= "800";

int y= Integer.parseInt(z);// use only numbers..we get exception....if we give String as  "meer"

System.out.println(y);

String k =String.valueOf(y);

ExceptionHandling

System.out.println("A");

try{

System.out.println("B");

int i= 8/0;

}catch(Exception e){

System.out.println("C");

System.out.println("error" +e.getMessage());

e.printStackTrace();

System.out.println("D"); 

 //will get output as A  B java.lang.ArithmeticException: / by zero

at Exception.ExceptionHandling.main(ExceptionHandling.java:10)   C  error/ by zero  D

Throws and Throw :

public static void clickLink() throws InterruptedException

 Interrupted Exception Thrown when a thread is waiting, sleeping, or otherwise occupied, and the thread is interrupted, either before or during the activity. Occasionally a method may wish to test whether the current thread has been interrupted, and if so, to immediately throw this exception. The following code can be used to achieve this effect:

  if (Thread.interrupted())  // Clears interrupted status!
      throw new InterruptedException();