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Wrapper Classes And String 
Satyam Shrivastav
Wrapper Classes
Primitive Data Type => Wrapper Class Object 
1.Using Constructor 
syntax : 
Integer i1 = new Integer(int); 
Integer i2 = n...
Wrapper Class Object => Primitive Data Type 
1.Using method 
xxxValue() 
syntax : 
Integer io=Integer.valueOf(254) 
int i=...
Primitive String Object => Wrapper Class Object 
1.Using Constructor 
syntax : 
Integer i1 = new Integer(“primitiveType”);...
Primitive String Object => Primitive Data Type 
//1.Primitive String Object =>Primitive String Object => 
Primitive Data T...
Wrapper Class Object => String Object 
1.using method 
toString() 
syntax : 
Integer io=new Integer(254); 
String s=io.toS...
Primitive Data Type => Non String Object 
1.using method 
toString(primitive type) 
syntax : 
String s=Integer.toString(10...
String
String 
 String is a sequence of characters placed in double quote(“ ”). 
 Strings are constant , their values cannot be...
How to create String object 
 There are two ways to create String object: 
1)By string literal. 
2)By new keyword. 
 1)B...
2) By new keyword:- 
For Example: String s=new String(“Sachin"); 
String s=new String(“SachinTendulkar");//create two obje...
Immutability 
• In java, string objects are immutable. Immutable simply means 
unmodifiable or unchangeable. 
• Once strin...
Advantages Of Immutability 
Use less memory: 
String word1 = "Java"; 
String word2 = word1; 
String word1 = “Java"; 
Strin...
Disadvantages of Immutability 
 Less efficient — you need to create a new string and throw 
away the old one even for sma...
Constructors 
 No Argument Constructors: 
No-argument constructor creates an empty String. Rarely used. 
Example: String ...
String Methods 
 substring(int begin): 
 Returns substring from begin index to end of the String. 
 Example: String s=“...
length() , charAt() 
int length(); 
char charAt(i); 
 Returns the number of characters in the 
string 
 Returns the char...
New features of String 
 In 1.5 Version: 
 Wrapper classes are introduced. 
Example. 
String s = Integer.toString(10); 
...
StringBuffer, StringBuilder 
StringTokenizer
 Limitation of String in Java ? 
 What is mutable string? 
A string that can be modified or changed is known as mutable ...
Relations between StringBuffer, StringBuilder and 
StringToknizer: 
All These classes are final and subclass of Serializab...
StringBuffer 
 StringBuffer is a synchronized and allows us to mutate the 
string. 
 StringBuffer has many utility metho...
 StringBuffer Constructor: 
 1. public StringBuffer() 
 2. public StringBuffer(int capacity) 
 3. public StringBuffer(...
Method Use In StringBuffer 
 1. Append 
 2. Insert 
 3.Delete 
 4.Reverse 
 5.Replacing Character at given index
StringBuilder 
 StringBuilder is the same as the StringBuffer class 
 The StringBuilder class is not synchronized and he...
StringTokenizer 
 A token is a portion of a string that is separated from another 
portion of that string by one or more ...
Thank you…
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Java String

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Brief about String, StringBuilder and StringBuilder Classes in java.

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Java String

  1. 1. Wrapper Classes And String Satyam Shrivastav
  2. 2. Wrapper Classes
  3. 3. Primitive Data Type => Wrapper Class Object 1.Using Constructor syntax : Integer i1 = new Integer(int); Integer i2 = new Integer(String); 2.Using Method syntax : Integer i3 = Integer.valueOf(int);
  4. 4. Wrapper Class Object => Primitive Data Type 1.Using method xxxValue() syntax : Integer io=Integer.valueOf(254) int i=io.xxxValue();
  5. 5. Primitive String Object => Wrapper Class Object 1.Using Constructor syntax : Integer i1 = new Integer(“primitiveType”); 2.using method syntax : Integer i1=Integer.valueOf(“primitiveType”);
  6. 6. Primitive String Object => Primitive Data Type //1.Primitive String Object =>Primitive String Object => Primitive Data Type //2Primitive String Object => Primitive Data Type Using method parseInt(“primitive type”); syntax : String s1=Integer.parseInt(“100”)
  7. 7. Wrapper Class Object => String Object 1.using method toString() syntax : Integer io=new Integer(254); String s=io.toString()
  8. 8. Primitive Data Type => Non String Object 1.using method toString(primitive type) syntax : String s=Integer.toString(10);
  9. 9. String
  10. 10. String  String is a sequence of characters placed in double quote(“ ”).  Strings are constant , their values cannot be changed in the same memory after they are created.
  11. 11. How to create String object  There are two ways to create String object: 1)By string literal. 2)By new keyword.  1)By string literal: For Example: String s1=“welcome"; String s2=“welcome”; //no new object will be created
  12. 12. 2) By new keyword:- For Example: String s=new String(“Sachin"); String s=new String(“SachinTendulkar");//create two objects and one reference variable.
  13. 13. Immutability • In java, string objects are immutable. Immutable simply means unmodifiable or unchangeable. • Once string object is created its data or state can't be changed but a new string object is created.
  14. 14. Advantages Of Immutability Use less memory: String word1 = "Java"; String word2 = word1; String word1 = “Java"; String word2 = new String(word1); word1 OK Less efficient: wastes memory Java Java Java word2 word1 word2
  15. 15. Disadvantages of Immutability  Less efficient — you need to create a new string and throw away the old one even for small changes. Example: String word = “Java"; word= word.concat(“technologies”); word Java Java technologies
  16. 16. Constructors  No Argument Constructors: No-argument constructor creates an empty String. Rarely used. Example: String empty=new String();  Copy Constructors: Copy constructor creates a copy of an existing String . Also rarely used. Example: String word = new String(“Java”); String word2 = new String(word);  Other Constructors: Most other constructors take an array as a parameter to create a String. Example: char[] letters = {‘J’, ‘a’, ‘v’, ‘a’}; String word = new String(letters);//”Java”
  17. 17. String Methods  substring(int begin):  Returns substring from begin index to end of the String.  Example: String s=“nacre”; System.out.println(s.substring(2));//cre  equals():  To perform content comparision where case is important. Example: String s=“java”; System.out.println(s.equals(“java”));//true  concat(): Adding two strings we use this method Example: String s=“nacre”; s= s.concat(“software”); System.out.println(s);// nacresoftware
  18. 18. length() , charAt() int length(); char charAt(i);  Returns the number of characters in the string  Returns the char at position i. Character positions in strings are numbered starting from 0 – just like arrays. Returns: “Problem".length(); 7 “Window”. charAt (2); ’n'
  19. 19. New features of String  In 1.5 Version:  Wrapper classes are introduced. Example. String s = Integer.toString(10); System.out.println(s);//10  In 1.7 Version:  Java 7 extended the capability of switch case to use Strings also, earlier java versions doesn’t support this. If you are implementing conditional flow for Strings, you can use if-else conditions and you can use switch case if you are using Java 7 or higher versions.
  20. 20. StringBuffer, StringBuilder StringTokenizer
  21. 21.  Limitation of String in Java ?  What is mutable string? A string that can be modified or changed is known as mutable string. StringBuffer and StringBuilder classes are used for creating mutable string.  Differences between String and StringBuffer in java? Main difference between String and StringBuffer is String is immutable while StringBuffer is mutable
  22. 22. Relations between StringBuffer, StringBuilder and StringToknizer: All These classes are final and subclass of Serializable.
  23. 23. StringBuffer  StringBuffer is a synchronized and allows us to mutate the string.  StringBuffer has many utility methods to manipulate the string.  This is more useful when using in a multithreaded environment.  Always modified in same memory location.
  24. 24.  StringBuffer Constructor:  1. public StringBuffer()  2. public StringBuffer(int capacity)  3. public StringBuffer(String s)  4. public StringBuffer(CharSequence cs)
  25. 25. Method Use In StringBuffer  1. Append  2. Insert  3.Delete  4.Reverse  5.Replacing Character at given index
  26. 26. StringBuilder  StringBuilder is the same as the StringBuffer class  The StringBuilder class is not synchronized and hence in a single threaded environment, the overhead is less than using a StringBuffer.
  27. 27. StringTokenizer  A token is a portion of a string that is separated from another portion of that string by one or more chosen characters (called delimiters).  The StringTokenizer class contained in the java.util package can be used to break a string into separate tokens. This is particularly useful in those situations in which we want to read and process one token at a time; the BufferedReader class does not have a method to read one token at a time
  28. 28. Thank you…

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