core java certification

　　　　5 Btn.addactionlistener (Lsner); // as soon as a button is pressed, Lsner will be notified.View CodeThe listener class that implements the ActionListener interface must have a actionperformed method:1 classMyListener implements ActionListener2 3 {4 5 ... ..6 7 　　 Public voidActionperformed (ActionEventEvent)8 9{//as soon as the user taps the button, JButton creates a ActionEvent object that calls this method to pass the event object.Ten One 　　　　 //reaction to button click Goes here A -

{ //System.out.println ("thread [" + name + "] Get message:" + exchanger.exchange (name + "-msg")); //without setting the timeout time, the thread will always block waitingSYSTEM.OUT.PRINTLN ("thread [" + name + "] Get message:" + exchanger.exchange (name + "-msg", 5, Timeunit.seconds));//set the time-out for 5 secondsSYSTEM.OUT.PRINTLN ("thread [" + Name + "]over"); } Catch(interruptedexception e) {e.printstacktrace (); } Catch(TimeoutException e) {//TODO auto-generated Catch blockE

A basic data structureMust be included in the classMust have public static Main methodCase sensitiveIi. Types of dataFour types of integers:INT 4 byte short 2 byte Long8 byte byte1 byteTwo floating-point typesFloat 4 bytesDouleble 8 bytesChar Type, Boolean typeConstants use the final definition class constants using the static final definitionThird, Operation symbolsX!=0 1/x>x+y//If x=0, do not perform the calculation behind avoid x=0 1/x operationMathematical operation symbol MATH.PI, etc.Iv.

If multithreading is to concurrently modify a data structure, such as a hash table, it can easily break this data structure. A thread may want to start inserting a new element into the table. Assume that you are deprived of control during the process of adjusting the link relationship between buckets of a hash table. If another thread also starts traversing the same linked list, it may use invalid links and cause confusion, throw an exception, or fall into a dead loop.You can protect shared data

frame: jQuery1.9.CSS Framework: Bootstrap 4 MetronicClient authentication: Jqueryvalidation Plugin.Rich Text: CkecitorFile Management: CkfinderDynamic tab: JerichotabData table: Jqgriddialog box: JQuery jboxTree structure controls: JQuery ZtreeOther components: Bootstrap 4 metronic3. SupportServer middleware: Tomcat 6, 7, Jboss 7, WebLogic 10, WebSphere 8Database support: Currently only support MySQL database, but not limited to the database, the next version of the upgrade multi-data source sw

(list1.getclass () = = List2.getclass ());}Can try the results, I packed the tickets, the result is true3, attention.A generic parameter type can only be a reference type, not a basic data type, such as an int4, use of generics4.1 Generic classpublic class Generictest {public static void Main (string[] args) {GENERICCLASSG1 = new genericclassG1.setkey (1);System.out.println (G1.getkey ());}}Class genericclass{Private T key;public void Setkey (T key) {This.key = key;}Public T GetKey () {return t

frame: jQuery1.9.CSS Framework: Bootstrap 4 MetronicClient authentication: Jqueryvalidation Plugin.Rich Text: CkecitorFile Management: CkfinderDynamic tab: JerichotabData table: Jqgriddialog box: JQuery jboxTree structure controls: JQuery ZtreeOther components: Bootstrap 4 metronic3. SupportServer middleware: Tomcat 6, 7, Jboss 7, WebLogic 10, WebSphere 8Database support: Currently only support MySQL database, but not limited to the database, the next version of the upgrade multi-data source sw