Java Fundamentals 12

1 Overview of the StringBuffer1.1 StringBuffer

• If we need to stitch the strings, each stitch will build a new string object, which is time consuming and wasted space. And stringbuffer can solve this problem.
• StringBuffer is a thread-safe sequence of characters.

1.2 Construction methods

• Construction method: No-parameter construction method

 Public StringBuffer ()

• Construction Method: Specifies the capacity of the string buffer

 Public StringBuffer (int capacity)

• Constructor method: Specify string contents of a string buffer

 Public StringBuffer (String str)

• Example:

 PackageCom.xuweiwei; Public classStringbufferdemo { Public Static voidMain (string[] args) {//Public StringBuffer ()StringBuffer SB =NewStringBuffer (); System.out.println ("SB:" +SB); System.out.println ("SB's Capacity:" +sb.capacity ()); System.out.println ("SB's Length:" +sb.length ()); //Public stringbuffer (int capacity)StringBuffer SB2 =NewStringBuffer (50); System.out.println ("SB2:" +SB2); System.out.println ("Capacity of SB2:" +sb2.capacity ()); System.out.println ("Length of SB2:" +sb2.length ()); //Public StringBuffer (String str)StringBuffer SB3 =NewStringBuffer ("Hello"); System.out.println ("SB3:" +SB3); System.out.println ("Capacity of SB3:" +sb3.capacity ()); System.out.println ("Length of SB3:" +sb3.length ()); }}

1.3 StringBuffer Add-on features

• Method: You can add any type of data to the string buffer and return the string buffer itself, which has overloaded methods

 Public StringBuffer append (String str)

• Method: Inserts any type of data into the string buffer at the specified location and returns the string buffer itself, which has overloaded methods

 Public StringBuffer Insert (int  offset,string str)

• Example:

 PackageCom.xuweiwei; Public classStringBufferDemo2 { Public Static voidMain (string[] args) {StringBuffer sb=NewStringBuffer (); //Public stringbuffer Append (String str)Sb.append ("Hello"); Sb.append (true); Sb.append (12); Sb.append (A); System.out.println ("SB:" +SB); Sb.insert (0, ' d '); System.out.println ("SB:" +SB); }}

1.4 StringBuffer Removal function

• Method: Delete The character at the specified position, note that the deletion is one, and return the string buffer itself

 Public StringBuffer Deletecharat (int index)

• Method: Deletes the content within the specified range and returns the string buffer itself

 Public StringBuffer Delete (int  start,int end)

• Example:

 PackageCom.xuweiwei; Public classStringBufferDemo2 { Public Static voidMain (string[] args) {StringBuffer sb=NewStringBuffer (); Sb.append ("Hello"); Sb.append (true); Sb.append (12); Sb.append (A); Sb.insert (0, ' d '); System.out.println ("SB:" +SB); Sb.deletecharat (0); System.out.println ("SB:" +SB); Sb.delete (The); System.out.println ("SB:" +SB); }}

1.5 StringBuffer Replacement function

• Method: From start to end, replace with STR, return the string buffer object

 Public StringBuffer replace (intint end,string str)

• Example:

 Package Com.xuweiwei;  Public class StringBufferDemo2 {    publicstaticvoid  main (string[] args) {         New StringBuffer ();        Sb.append ("Hello"). Append ("World"). Append ("Java");        Sb.replace (5, 10, "Hello, World");        System.out.println ("SB:" + SB);    }}

1.6 StringBuffer reversal function

• Method:

 Public StringBuffer reverse ()

• Example:

 Package Com.xuweiwei;  Public class StringBufferDemo2 {    publicstaticvoid  main (string[] args) {         New  stringbuffer ();        Sb.append ("Hello"). Append ("World"). Append ("Java");        System.out.println ("SB:" + Sb.reverse ());}    }

interception function of 1.7 stringbuffer

• Method: Intercepts the content from the specified position, returning the string object

 Public String substring (int start)

• Method: Truncate from the specified position to the end of the specified position, returning the string object

 Public String substring (int start,int end)

• Example:

 Package Com.xuweiwei;  Public class StringBufferDemo2 {    publicstaticvoid  main (string[] args) {         New StringBuffer ();        Sb.append ("Hello"). Append ("World"). Append ("Java");        System.out.println ("SB:" + SB);         = sb.substring (3);        System.out.println ("SB:" + SB);        SYSTEM.OUT.PRINTLN ("str:" + str);}            }

Java Fundamentals 12