20165215 2017-2018-2 "Java Programming" Week 8 Learning Summary

20165215 2017-2018-2 "Java Programming" Week 8 Learning Summary

Textbook learning content summary

• process and thread
  • A process is a dynamic execution process of a program, which corresponds to a complete process from code loading, execution to execution completion.
  • A thread is a smaller unit of execution than a process
• Process in Java
  • A computer can only execute one of those threads at any given moment
  • The Java language uses Threadobjects of classes and their subclasses to represent threads
  • After the thread is created, it only occupies memory resources, and the start() method must be called to notify the JVM
  • The program must override the run() method of the parent class in the child class
  • The sleep(int millsecond) method puts the current thread into a sleep state, and the wait() method makes the current thread enter a waiting state
  • The so-called dead state is that the thread releases the entity, that is, releases the memory allocated to the thread object
• Thread class and thread creation
  • The construction method usually used to create a thread using Thread is Thread (Runnable target)
  • When the target object is completely decoupled from the thread, the target object needs to obtain the name of the thread to determine which thread is occupying the CPU; in the target object combined thread, the target object can obtain a reference to the thread object
• Common method
  • start();
  • run(), before the thread ends run(), do not let the thread call the start() method, otherwise an IllegalThreadStateException will occur
  • sleep(int millsecond) must call the sleep method in a try-catch block
  • isAlive();
  • currentThread() returns the thread that is currently using CPU resources
  • interrupt();
• Thread synchronization mechanism: when a thread A uses the synchronized method, it must wait until thread A finishes using the synchronized method
• You cannot use wait(), notify(), notifyAll() in unsynchronized methods
• A uses Join() to join B during operation, then the A thread immediately executes the terminal, and waits for the execution of B to end, and A re-queues to wait for CPU resources
• The AWT-EventQueue thread is responsible for handling GUI events, and the AWT-Windows thread is responsible for drawing forms or components to the desktop

Problems and solutions in code debugging

• Question 1: The following error occurs when compiling example 1

• Problem 1 solution: add encodingparameter: javac -encoding gbk Example12_1.java, then run successfully

code hosting

(screenshot of the running result of the statistics.sh script)

Summary of last week's exam mistakes

• wrong question 1

• Understanding the situation: Xammp is a powerful website integration software package in which databases can be created
• wrong question 2

• Understanding: Data manipulation language refers to querying, inserting, deleting, and modifying data in tables
• wrong question 3

• Understanding the situation: java.sql.SQLException: Unknown column 'sid' in 'field list' means that there is an unknown column "SID" in the "field list"

learning progress bar

	Lines of code (added/accumulated)	Blog volume (new/cumulative)	Study time (added/accumulated)	important growth
Target	5000 lines	30 articles	400 hours
the first week	37/37	1/1	15/15
the second week	398/429	2/3	15/30
The third week	753/1167	1/4	20/50
the fourth week	1296/2109	2/6	20/70
fifth week	1191/3323	2/8	20/90
Week 6	1806/4390	2/10	15/105
Week 7	1260/5145	2/12	15/120
eighth week	606/5745	3/15	20/140

References

• "Java2 Practical Tutorial (Fifth Edition)"