New Features of jdk1.7

1. You can use a string in the switch.

In earlier versions, data of the string type in the switch statement block is not supported. This function has long been supported in C #. Fortunately, jdk1.7 is added.

String S = "test";Switch(S ){Case"Test": System. Out. println ("Test");Case"Test1": System. Out. println ("Test1");Break;Default: System. Out. println ("Break");Break;}
 

2. Automatic Inference of generic instantiation types

List <string> templist =NewArraylist <> ();
 

3. Enhanced support for Java collections

In versions earlier than jdk1.7, the form of access elements in Java Collection containers is as follows.ToList,Set,MapThe collection container is used as an example:

 //  Create a list interface object List <string> List = New Arraylist <string> (); List. Add ( "Item ");//  Use the add () method to obtain an object String item = list. Get (0 ); //  Get object using get () method  //  Create a set interface object Set <string> set = New Hashset <string> (); Set. Add ( "Item "); //  Add an object using the add () method  //  Create a map interface object Map <string, integer> map = New Hashmap <string, integer>(); Map. Put ( "Key", 1 ); //  Add an object using the put () method  Int Value = map. Get ("key ")

In jdk1.7, Java Collection interface implementation classes are discarded, such as arraylist, hashset, and hashmap. Instead, the object is saved in the form of [] and {}, and the object in the set is obtained in the form of [] according to the index and key value, as follows:

List <string> List = ["item"];//Add an element to a list setString item = list [0];//Retrieve elements from the list setSet <string> set = {"item "};//Add an element to a set objectMap <string, integer> map = {Name: "XXX", age: 18};//Add objects to the map setIntValue = map ["Age"];//Get objects from the map set
 

4. New tools and methods for retrieving Environment Information

File System. getjavaiotempdir ()//Io Temporary FolderFile System. getjavahomedir ()//JRE installation directoryFile System. getuserhomedir ()//Current user directoryFile System. getuserdir ()//Directory where the JAVA process is started......
 

5. boolean type inversion, null pointer security, and bit operation

 //  Type inversion, null pointer Security Boolean booleans. Negate (Boolean booleanobj) //  True => false, false => true, null => null  // Involved in bitwise operation  Boolean Booleans. And ( Boolean  [] Array)  Boolean Booleans. Or ( Boolean  [] Array)  Boolean Booleans. XOR ( Boolean  [] Array)  Boolean  Booleans. And (Boolean [] array)  Boolean  Booleans. Or (Boolean [] array) Boolean Booleans. XOR (Boolean [] array)

6. Equals between two char

 
BooleanCharacter. equalsignorecase (CharSuccess,CharCH2)
 

7. Safe addition, subtraction, multiplication, division

 Int Math. safetoint ( Long  Value)  Int Math. safenegate ( Int  Value)  Long Math. safesubtract (Long Value1, Int  Value2)  Long Math. safesubtract ( Long Value1, Long  Value2)  Int Math. safemultiply ( Int Value1, Int  Value2)  Long Math. safemultiply ( Long Value1, Int Value2)  Long Math. safemultiply ( Long Value1, Long  Value2)  Long Math. safenegate ( Long  Value)  Int Math. safeadd ( Int Value1, Int  Value2)  Long Math. safeadd ( Long Value1,Int  Value2)  Long Math. safeadd ( Long Value1, Long  Value2)  Int Math. safesubtract ( Int Value1, Int Value2)

8. The value can be underlined.

 
IntOne_million = 0000000_000;
 

9. Support for binary text

 
IntBinary = 0b1001_1001;