The document discusses the Character class and String class in Java. The Character class represents a single character/letter. It has methods like isLetter() and toUpperCase(). The String class represents a sequence of characters. Strings are immutable in Java so the StringBuffer and StringBuilder classes are used when mutability is needed. These classes have methods like append(), reverse(), delete(), and insert() for modifying string values.

1. Character class and String Class
•What is character class?
•What are methods in character class
•Tasks?
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2. Character class
• Using objects instead of primitive data types is
known as wrapper class.
• Converting Primitive data type to object data is
known as Boxing
Character ob=new Character(‘j’);
• Character objects has advantage of auto-
boxing and un-boxing.
• Escape Sequence: A character preceded by a
backslash is an esc sequence. /b,/t,/n/,//,/r,/’,/’’
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3. Character’s sub classes Methods
• isLetter(): whether the specified character is a letter.
• isDigit(): whether the specified character is a digit.
• isWhitespace(): Determines whether specified
character value is white space.
• isUpperCase()/isLowerCase(): for case identification.
No return any value.
• toUpperCase()/toLowerCase(): returns upper/lower
case value.
• toString(): returns one character string value.
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4. String Class
• In other we say collection of characters.
• In Java programming language, strings are treated
as objects.
• String class is used in java for creation and
Manipulation of strings.
• We can Create Strings directly as shown below
• String ob= “MUETCSE”;
• Char c ={‘M’, ‘U’, ‘E’, ‘T’} this will be called by
using new Keyword through constructor.
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5. String Class Cont…
• When an String object is created it is valued
cannot modified or changed.
• So we Can by using StringBuffer and
StringBuilder Classes.
• Methods of both classes are same but
SetBuilder class methods is not thread safe so
those are fast.
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6. StringBuffer Class Methods
• StringBuffer append(String s): append(combine)
the object’s value that invokes this method.
• StringBuffer reverse(): Reverse the value of the
string object that invokes this method.
• public delete(int start, int end): Deletes the
objects value from given starting index to last
index’s value.
• public insert(int offset, int i): Inserts an string at
the address given in the offset.
• replace(int start, int end, String str): For
Replacement of the value
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