Java Lecture Notes - 2012.02.23

Integer class's main methods
        String toString() : number to character
 

        static int parseInt(String str) throws  

        NumberFormatException    //static->class.access by
 

        static String toBinaryString(int num):character binary(2,16,8base) form return as

             //(Binary/HexString/OctalString)
 

        static Integer valueOf(String str)
        throws NumberFormatException    //string-> int form cast

 

 

System class
       class variable : in(keyboardfrom receive) out(monitoroutput) err(erroroutput)
 

       System.out.println()   // System:classname /out:static objectfunction   

       static void arraycopy  //array copy

       (Object source, int sourceStart, Object target, int size)

       static void exit(int exitcode)  -> execution method : System.exit(0) 

               = normal termination (0 other than's value=abnormal termination)

               Java auto unused memory destroys but,
               that point in time advance for use.(however, immediately memory deleted not)

 

 

 

 

exception overview
      program execution during occurring unexpected not event. (execution error)

      more complete program compose purposeto exception handling .

 
    use
           integer 0to dividing case

           array subscript negative or scope exceeding case

           improper type conversion occurrence case
           I/O for file none case
 

    exception handling related basic class
           Error : program code 's to be handled error
           Exception : possible error
 

    Java exception object

          Java programfrom Error(X), RuntimeException class sub class
           all exception handlingby
 

          occurrenceto Error, RuntimeException(X) class(sub class include)
           exception programfrom handlingto
                   : exception handlingby  
                   exception handling for un size because
  

          Error class sub classonly program errorhandling cannot.

    

    Exception class sub class
          CloneNotSupportedException object toto onfrom's
          InterruptedException thread of when  

          RuntimeException executiontime exception when
          ArithmeticException 0to dividing 's exception (operationerror)

          NegativeArraySizeException array size specify when negative's use

          IndexOutOfBoundException array 's scope access.

          NullPointerException null object method member variable access when 

               (referencevariable object to nullofonof access)
 

    exception handling

          exception method within handling (try, catch use)

          's trynot catch use .

          exception method call method exception handling main

          (throws use)

  
   ofto exception :exception when occurring for throw use

          throw exceptionobject;
          throw new exceptionobjecttype(parametervariable);

          public void c() throws exceptionclass[, exceptionclass, ….]  

               // c()functionnotfrom error when, + .

   
   use exception definitionby use can

          "Exception classfrom inheritance"

          must, creationmust have,

          creation not super(value) Exception pass value contained .

             (creation class?,inheritance not)