Java -- what is the difference between String, StringBuilder, and StringBuffer ?, Javastringbuffer

Java -- what is the difference between String, StringBuilder, and StringBuffer ?, Javastringbuffer

1. String is a read-only String, and the referenced String content cannot be changed.

2. The StringBuffer and StringBuilder string objects can be directly modified.

3. StringBuilder is not modified by the synchronized keyword. The thread is not secure, the efficiency is higher than that of StringBuffer, And the StringBuffer thread is secure.

4. If the connected string already exists in the static storage area, the "+" performance is superior to the append method of StringBuffer/StringBuilder.