Features added in Java7.0 :

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• Strings in switch : In earlier versions the switch only accepts (int,short,byte,char,enum) and from this version onward String also included in the list.

Example:

class Test 
{
 public static void main(String[] ar)
 {
 String time = "morning";
 switch(time){
  case "morning": 
   System.out.print("Good Morning");
   break; 
  case "noon": 
   System.out.print("Good AfterNoon");
   break;
  case "night": 
   System.out.print("Good Night");
   break;
 }
}
}

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• try with Resource : Automatic resource management in try-statement.Any object that implements java.lang.AutoCloseable , which includes all objects which implement java.io.Closeable , can be used as a resource.

Example:

import java.io.*;
class Test
{
 public static void main(String[] ar)
 {
  try(FileReader f=new FileReader("ab.txt"))
  {
   int i;
   while((i=f.read())!=-1)
    System.out.print((char)i);
  }
  catch(Exception e){
    System.err.print(e.getMessage());
  } 
 }
}

---

• Improved type inference for generic instance creation, the diamond operator <>.

Example:

import java.util.*;
class Test
{
 public static void main(String[] ar)
 {
   ArrayList< String> al;
   al = new ArrayList<>(); //<>
   al.add("Albert");
   al.add("Bob");
   al.add("Peter");
   System.out.print(al);
 }
}

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• Simplified Varargs Method Invocation :
  When a programmer tries to invoke a *varargs* (variable arity) method with a non-reifiable varargs type, the compiler currently generates an "unsafe operation" warning. JDK 7 moves the warning from the call site to the method declaration. This will enable API designers to use varargs due to the reduction of warnings reported.

  ---

• Binary Integer Literal : Java code, due to its C heritage, has traditionally forced programmers to represent numbers in only decimal, octal, or hexadecimal.
  As quite a few domains are bit orientated, this restriction can introduce errors. You can now create binary numbers using an 0b prefix.

Example

class Test 
{
 public static void main(String[] ar)
 {
   int i = 0b101; //binary literal
   System.out.print(i);  //5
 }
}

---

• Allowing underscores in numeric literals : Long numbers are hard to read. You can now split them up using an underscore in ints and longs.

Example

class Test 
{
 public static void main(String[] ar)
 {
   int i = 1_000_00;  //underscore
   System.out.print(i);  //100000
 }
}

---

• Catch with Multiple Exception :
  Catching multiple exception types and rethrowing exceptions with improved type checking.

Example

class Test 
{
 public static void main(String[] ar)
 {
  try{
   String s=null;
   s.toUpperCase();
   int i = Integer.parseInt(s);
  }
  catch(NullPointerException|NumberFormatException e){
   System.err.print(e.getMessage());
  }
 }
}

---

• New file I/O librar (defined by JSR 203) adding support for multiple file systems, file metadata and symbolic links.

• The new packages are java.nio.file, java.nio.file.attribute and java.nio.file.spi.

• Enhanced library-level support for new network protocols, including SCTP and Sockets Direct Protocol.

• Timsort is used to sort collections and arrays of objects instead of merge sort.