Java StringBuilder All working explained in detail || Java tutorial || Strings concept смотреть онлайн

In this video we are going to study about StringBuilder in java
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THEORY OF STRING BUILDER FOR REFERERNCE---)

The StringBuilder Class
StringBuilder objects are like String objects, except that they can be modified. Internally, these objects are treated like variable-length arrays that contain a sequence of characters. At any point, the length and content of the sequence can be changed through method invocations.

Strings should always be used unless string builders offer an advantage in terms of simpler code (see the sample program at the end of this section) or better performance. For example, if you need to concatenate a large number of strings, appending to a StringBuilder object is more efficient.
StringBuilder Operations
The principal operations on a StringBuilder that are not available in String are the append() and insert() methods, which are overloaded so as to accept data of any type. Each converts its argument to a string and then appends or inserts the characters of that string to the character sequence in the string builder. The append method always adds these characters at the end of the existing character sequence, while the insert method adds the characters at a specified point.

Here are a number of the methods of the StringBuilder class.

Various StringBuilder Methods
Method Description
StringBuilder append(boolean b)
StringBuilder append(char c)
StringBuilder append(char[] str)
StringBuilder append(char[] str, int offset, int len)
StringBuilder append(double d)
StringBuilder append(float f)
StringBuilder append(int i)
StringBuilder append(long lng)
StringBuilder append(Object obj)
StringBuilder append(String s) Appends the argument to this string builder. The data is converted to a string before the append operation takes place.
StringBuilder delete(int start, int end)
StringBuilder deleteCharAt(int index) The first method deletes the subsequence from start to end-1 (inclusive) in the StringBuilder's char sequence. The second method deletes the character located at index.
StringBuilder insert(int offset, boolean b)
StringBuilder insert(int offset, char c)
StringBuilder insert(int offset, char[] str)
StringBuilder insert(int index, char[] str, int offset, int len)
StringBuilder insert(int offset, double d)
StringBuilder insert(int offset, float f)
StringBuilder insert(int offset, int i)
StringBuilder insert(int offset, long lng)
StringBuilder insert(int offset, Object obj)
StringBuilder insert(int offset, String s) Inserts the second argument into the string builder. The first integer argument indicates the index before which the data is to be inserted. The data is converted to a string before the insert operation takes place.
StringBuilder replace(int start, int end, String s)
void setCharAt(int index, char c) Replaces the specified character(s) in this string builder.
StringBuilder reverse() Reverses the sequence of characters in this string builder.
String toString() Returns a string that contains the character sequence in the builder.
Note: You can use any String method on a StringBuilder object by first converting the string builder to a string with the toString() method of the StringBuilder class. Then convert the string back into a string builder using the StringBuilder(String str) constructor.