Technical support knowledge point summary for 11 weeks

Code summary:
[Java]
Package cn.com. cnstrong;
 
Import java. util. Date;
Import java. text. ParseException;
Import java. text. SimpleDateFormat;
 
 
 
 
Public class DataDemo
{
 
/**
* @ Param args
*/
Public static void main (String [] args)
{
// TODO Auto-generated method stub
Date date = new Date ();
System. out. println (date );

// Format the date at 10:30:07 on January 9
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd HH: mm: ss ");
String str = sdf. format (date );
System. out. println (str );

String s1 = "2010-10-10 ";
SimpleDateFormat sdf1 = new SimpleDateFormat ("yyyy-MM-dd"); // an exception must be caught.
Try // monitoring code
{
Date d1 = sdf1.parse (s1 );
System. out. println (d1 );

}
Catch (ParseException e)
{
E. printStackTrace ();
}
}
}

// Finally used for resource release
// Exceptions are thrown up layer by layer. 1. Non-runtime exceptions. 2. runtime exceptions ·
// Compile and explain the execution
// Must be captured
// Your code must be released
// Handle exceptions in a timely manner
// When handling exceptions in catch, make the parent class at the bottom when there is a parent class

 
[Java]
Package cn.com. cnstrong;
 
Public class StringBufferDemo {
 
/**
* @ Param args
*/
Public static void main (String [] args ){
// TODO Auto-generated method stub
StringBuffer sb = new StringBuffer ();
Sb. append ("a1 ");
Sb. append ("a1 ");
Sb. append ("a1 ");
Sb. append ("a1 ");
System. out. println (sb. toString ());
System. out. println (sb. capacity (); // The default value is 16.
System. out. println (sb. length ());
 
}
 
}
[Java]
Package cn.com. cnstrong;
 
Public class StringDemo1 {
 
/*
* @ Param args
*/
Public static void main (String [] args ){
// TODO Auto-generated method stus
String s = new String ("abc ");
String s1 = "abc ";
String s2 = new String ("abc ");
System. out. println (s = s1 );
System. out. println (s = s2 );
System. out. println (s2 = s1 );

 
}
 
}

 
[Java]
Package cn.com. cnstrong;
 
Public class StringDemo2 {
 
/**
* @ Param args
*/
Public static void main (String [] args ){
// TODO Auto-generated method stub
String str1 = new String ("AB cd ");
String str2 = new String ("abcdwtryreuytrab ");
String str3 = "ABC ";//?
// What is the difference!
Str1 = "AB" + "cd"; // concatenates strings and three objects to produce a lot of garbage
// What is used?
//
System. out. println (str1.length ());
System. out. println (str1.startsWith ("AB "));
System. out. println (str1.indexOf ("AB"); // contains characters
System. out. println (str1.indexOf ("AB", 2 ));//?
System. out. println (str1.substring (3 ));//?
System. out. println (str1.trim () + "| ");
// Replace
// Trim // remove space
// Equals comparison content
// = Whether the same object
String str4 = "1, 2, 3, 4, 5, 6, 7, 8 ";
String array [] = str4.split (","); // capture String
For (String ss: array)
{
System. out. println (ss );

}
//



 
}
 
}

 
[Java]
Package cn.com. cnstrong;
 
Public class StringDemo3 {
 
/**
* @ Param args
*/
Public static void main (String [] args ){
// TODO Auto-generated method stub
String str1 = "123 ";

// String --> int
Int num = Integer. parseInt (str1 );
{
System. out. println (num );
}
// Int --> String
String s1 = String. valueOf (num );
{
System. out. println (s1 );
}

// String --> float
Float f = Float. parseFloat (s1 );
{
System. out. println (f );
}
// Float --> String
String str2 = String. valueOf (f );
{
System. out. println (str2 );

}
// Auto-Boxed int -- Integer
Int num1 = 4;
Integer I = num1;
// Float f = Float. parseFloat (str1); automatic packing

// Automatically Unbox Integer -- int
Int num2 = I;
// Integer is the int packaging class
}
 
}