Java Basic Knowledge Summary (String, StringBuffer, StringBuilder)

1.String string:

The string class is described in Java. Encapsulates the object with a string. The advantage is that you can easily manipulate the common data of strings. After the object is encapsulated, you can define n multiple properties and behaviors.

How do I define a string object? string s = "abc"; The data that is caused by double quotation marks is a string object.

　　features : Once the string is initialized, it cannot be changed and stored in a constant pool in the method area.

　　

String S1 = "abc"; //S1 points to only one object in memory ABC .

string s2 = new String ("abc"); //S2 has two objects pointing to the content ABC ,new.

System.out.println (S1==S2);//false

System.out.println (s1.equals (S2));//true, in the string equals compares the contents of the strings.

Method of String:

1: Constructor method: converts a byte array or an array of characters into a string.

string S1 = new string ();//A string that creates an empty content.

String s2 = Null;//s2 does not have any object pointing, it is a null constant value.

string s3 = "";//s3 points to a specific string object, except that there is no content in the string.

New String (char[]);//Converts a character array into a string.

New String (char[],offset,count);//Converts a portion of a character array into a string.

2.StringBuffer String Buffer:

constructs a string buffer with no characters, with an initial capacity of three characters.

Characteristics:

1: You can modify the contents of a string.

2: is a container.

3: Is variable-length.

4: Any type of data can be stored in the buffer.

5: Eventually it needs to become a string.

3.StringBuilder String Buffer:

JDK1.5 appeared stringbuiler; constructs a string generator with no characters, with an initial capacity of three characters.

This class is designed to be used as StringBuffer a simple replacement for a string buffer that is used by a single thread (this is common). Method is the same as StringBuffer;

The difference between StringBuffer and StringBuilder:

StringBuffer thread safety.

StringBuilder thread is not secure.

single-threaded operation, using StringBuilder high efficiency.

Multi-threaded operation, using StringBuffer safe.

Java Basic Knowledge Summary (String, StringBuffer, StringBuilder)