java sample programs for interview

Give a string, replace more than two _ to one, such as "Hello__world____are__you_ok?", should be treated as "Hello_world_are_you_ok?", the sample code is as follows: Using regular expressions, a word-out version:public static void Main (string args[]) {string str= "Hello__world____are__you_ok?";System.out.println (Str.replaceall ("[_]+", "_")); } Output: Hello_world_are_you_ok?The more troublesome version:public static string replace (String str)

Why do I need multiple threads?Simplification of the model, such as some programs are run by a number of relatively independent tasks: The appearance of graphical interface, the blocking of input and output Multi-core CPU for better utilization The need for asynchronous behavior Java Multi-Threading features: The entry of the program main itself is a thread Threads are concurrent, unordered execution

Using Java to implement serial communication (under Windows System), we need to use the port package Javacomm20-win32.zip provided by Sun. There are three files to use, such as the following configuration:1.comm.jar placed to Java_home/jre/lib/ext;2.win32com.dll placed to Java_home/bin;3.javax.comm.properties two places to put them.Jre/lib (that is, the JRE in the Java directory)Java_home/jre/libTell me abo