The difference between StringBuffer and StringBuilder

1.  Comparison of speed of execution: StringBuilder >  stringbuffer   
2.  StringBuffer and StringBuilder, they are string variables, are objects that can be changed, and whenever we use them to manipulate strings,
Actually operates on an object and does not create as many objects as a string, so the speed is fast.
3.  StringBuilder: Thread non-secure
　  StringBuffer: Thread-safe
    When we are using a string buffer to be used by multiple threads, the JVM does not guarantee that the StringBuilder operation is safe, although he is the fastest, but can ensure that the StringBuffer can be operated correctly. Of course, most of the time we are in a single-threaded operation, so in most cases it is recommended to use StringBuilder instead of StringBuffer, which is the reason for speed.

Summary of the use of the three: 1. If you want to manipulate a small amount of data with = String
　　　　　　       2. Manipulating large amounts of data under a single-threaded operation string buffer = StringBuilder
　　　　　　       3. Multi-threaded operation string buffer operation large amount of data = StringBuffer

The difference between StringBuffer and StringBuilder