??xml version="1.0" encoding="utf-8" standalone="yes"?>
/**
* @param args
* @throws java.text.ParseException
*/
public static void main(String[] args) throws java.text.ParseException {
// Date dateNow = new Date();
//
// String dateNowStr = dateFormat.format(dateNow);
// System.out.println(dateNowStr);
final String dayNames[] = { "星期?, "星期一", "星期?, "星期?, "星期?, "星期?,
"星期? };
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyqMM月dd?);
Calendar calendar = Calendar.getInstance();
Date date = new Date();
String datarq = dateFormat.format(date); //日期
calendar.setTime(date);
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK) - 1;
if (dayOfWeek < 0)
dayOfWeek = 0;
System.out.println(datarq + " " + dayNames[dayOfWeek]);
}
}
l常Q我们在启动应用的时候发现系l需要的端口被别的程序占用,如何知道谁占有了我们需要的端口Q很多h都比较头|下面׃l一U非常简单的ҎQ希望对大家有用?/p>
我们需要确定谁占用了我们的80端口
在windows命o行窗口下执行Q?br />
C:\>netstat -aon|findstr “80″
TCP 0.0.0.0:19780 0.0.0.0:0 LISTENING 2044
TCP 10.72.224.5:2558 96.17.109.8:80 ESTABLISHED 2044
TCP 10.72.224.5:2757 60.210.176.209:80 TIME_WAIT 0
TCP 10.72.224.5:3956 125.46.1.234:80 ESTABLISHED 2044
TCP 10.72.224.5:3959 125.46.1.234:80 ESTABLISHED 2044
UDP 0.0.0.0:2280 *:* 3700
看到了吗Q端口被q程号ؓ2044的进E占用,l箋执行下面命oQ?br />
C:\>tasklist|findstr “2044″
avp.exe 2044 Console 0 37,680 K
很清楚吧Qavp 卡巴监听80端口Q调整卡巴网l监听设|?br />
当然Q如果你?0端口被其他程序占用,kill掉或者调整端口?/p>
public class MyStack {
LinkedList mylist = new LinkedList();
public void push(Object o) {
mylist.addFirst(o);
}
public Object pop() {
return mylist.removeFirst();
}
public Object peek() {
return mylist.getFirst();
}
public boolean empty() {
return mylist.isEmpty();
}
public static void main(String[] args) {
MyStack ms = new MyStack();
ms.push("1");
ms.push("2");
ms.push("3");
ms.push("4");
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println(ms.peek());
System.out.println(ms.empty());
}
}
package l6;
import java.util.LinkedList;
/**
* 实现队列的数据结?br />
*
*/
public class MyQueue {
private LinkedList ll = new LinkedList();
public void put(Object o) {
ll.addLast(o);
}
public Object get() {
return ll.removeFirst();
}
public Object peek() {
return ll.getFirst();
}
public boolean empty() {
return ll.isEmpty();
}
/**
* @param args
*/
public static void main(String[] args) {
MyQueue mq = new MyQueue();
mq.put("1");
mq.put("2");
mq.put("3");
mq.put("4");
mq.put("5");
mq.put("6");
System.out.println(mq.get());
System.out.println(mq.get());
System.out.println(mq.get());
System.out.println(mq.get());
System.out.println(mq.peek());
System.out.println(mq.empty());
}
}
import java.util.Comparator;
public class Student implements Comparable {
public int num;
public String name;
public Student(int num, String name) {
this.num = num;
this.name = name;
}
public int compareTo(Object o) {
Student s = (Student) o;
if (num > s.num) {
return 1;
} else if (num == s.num) {
return 0;
} else {
return -1;
}
}
public String toString() {
return "num:" + num + " name:" + name;
}
public int compare(Object o1, Object o2) {
// TODO Auto-generated method stub
return 0;
}
}
//学生比较?br />
package l6;
import java.util.Comparator;
public class StudentComparator implements Comparator {
public int compare(Object o1, Object o2) {
Student s1 = (Student) o1;
Student s2 = (Student) o2;
if (s1.num > s2.num) {
return 1;
} else if (s1.num < s2.num) {
return -1;
} else {
return s1.name.compareTo(s2.name);
}
}
}
//试c?br />
package l6;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
public class ArrayListTest {
/**
* @param args
*/
public static void main(String[] args) {
ArrayList<Student> slist = new ArrayList<Student>();
Student s1 = new Student(1, "z1");
slist.add(s1);
Student s3 = new Student(2, "z3");
slist.add(s3);
Student s2 = new Student(2, "z2");
slist.add(s2);
Student s5 = new Student(2, "z5");
slist.add(s5);
Student s4 = new Student(4, "z4");
slist.add(s4);
// Collections.sort(slist); //未用比较器
Collections.sort(slist, new StudentComparator());//未用比较器
PaintE(slist);
}
public static void PaintE(Collection c) {
Iterator it = c.iterator();
while(it.hasNext()){
System.out.println(it.next().toString());
}
}
}
//All the divs and paragraphs
//note: this returns an array with all the divs first,then all the paragraphs:
$$('div', 'p');
//All the divs with the css class 'myClass':
$$('div.myClass')
/All the paragraphs that are inside divs:
$$('div p');
//All the bold tags in paragraphs with Class 'foo' in divs with class 'myClass':
$$('div.myClass p.foo b');
<2>addClass 应用
Examples:
HTML
<div id="myElement" class="testClass"></div>
JavaScript
$('myElement').addClass('newClass');
<3>removeClass 应用
Examples:
HTML
<div id="myElement" class="testClass newClass"></div>
JavaScript
$('myElement').removeClass('newClass');
Resulting HTML
<div id="myElement" class="testClass"></div>
<4>toggleClass 应用
Adds or removes the passed in class name to the Element, depending on whether or not it's already present.
Examples:
HTML
<div id="myElement" class="myClass"></div>
JavaScript
$('myElement').toggleClass('myClass');
Resulting HTML
<div id="myElement" class=""></div>
JavaScript
$('myElement').toggleClass('myClass');
Resulting HTML
<div id="myElement" class="myClass"></div>
Java关键?/span>final?#8220;q是无法改变?#8221;或?#8220;l态的”含义Q它可以修饰非抽象类、非抽象cL员方法和变量。你可能Z两种理解而需要阻止改变:设计或效率?/span>
finalcM能被l承Q没有子c,finalcM的方法默认是final的?/span>
finalҎ不能被子cȝҎ覆盖Q但可以被ѝ?/span>
final成员变量表示帔RQ只能被赋gơ,赋值后g再改变?/span>
final不能用于修饰构造方法?/span>
注意Q父cȝprivate成员Ҏ是不能被子类Ҏ覆盖的,因此privatecd的方法默认是finalcd的?/span>
1?/span>finalc?/span>
finalcM能被l承Q因?/span>finalcȝ成员Ҏ没有Z被覆盖,默认都是final的。在设计cL候,如果q个cM需要有子类Q类的实现细节不允许改变Qƈ且确信这个类不会载被扩展Q那么就设计?/span>finalcR?/span>
2?/span>finalҎ
如果一个类不允许其子类覆盖某个ҎQ则可以把这个方法声明ؓfinalҎ?/span>
使用finalҎ的原因有二:
W一、把Ҏ锁定Q防止Q何承类修改它的意义和实现?/span>
W二、高效。编译器在遇到调?/span>finalҎ时候会转入内嵌机制Q大大提高执行效率?/span>
3?/span>final变量Q常量)
?/span>final修饰的成员变量表C常量,g旦给定就无法改变Q?/span>
final修饰的变量有三种Q静态变量、实例变量和局部变量,分别表示三种cd的常量?/span>
4?/span>final参数
当函数参CؓfinalcdӞ你可以读取用该参数Q但是无法改变该参数的倹{?/span>
二?/span>static
static表示“全局”或?#8220;静?#8221;的意思,用来修饰成员变量和成员方法,也可以Ş成静?/span>static代码块,但是Java语言中没有全局变量的概c?/span>
?/strong>static修饰的成员变量和成员Ҏ独立于该cȝM对象。也是_它不依赖cȝ定的实例Q被cȝ所有实例共享。只要这个类被加载,Java虚拟机就能根据类名在q行时数据区的方法区内定扑ֈ他们。因此,static对象可以在它的Q何对象创Z前访问,无需引用M对象?/span>
?/strong>public修饰?/span>static成员变量和成员方法本质是全局变量和全局ҎQ当声明它类的对象市Q不生成static变量的副本,而是cȝ所有实例共享同一?/span>static变量?/span>
static变量前可以有private修饰Q表C个变量可以在cȝ静态代码块中,或者类的其他静态成员方法中使用Q当然也可以在非静态成员方法中使用--废话Q,但是不能在其他类中通过cd来直接引用,q一点很重要。实际上你需要搞明白Q?/span>private是访问权限限定,static表示不要实例化就可以使用Q这样就Ҏ理解多了?/span>static前面加上其它讉K权限关键字的效果也以此类推?/span>
static修饰的成员变量和成员Ҏ习惯上称为静态变量和静态方法,可以直接通过cd来访问,讉K语法为:
cd.静态方法名(参数列表...)
cd.静态变量名
?/span>static修饰的代码块表示静态代码块Q当Java虚拟机(JVMQ加载类Ӟ׃执行该代码块Q用处非常大Q呵呵)?/span>
1?/span>static变量
按照是否静态的对类成员变量q行分类可分两种Q一U是?/span>static修饰的变量,叫静态变量或cd量;另一U是没有?/span>static修饰的变量,叫实例变量。两者的区别是:
对于静态变量在内存中只有一个拷贝(节省内存Q,JVM只ؓ静态分配一ơ内存,在加载类的过E中完成静态变量的内存分配Q可用类名直接访问(方便Q,当然也可以通过对象来访问(但是q是不推荐的Q?/span>
对于实例变量Q没创徏一个实例,׃为实例变量分配一ơ内存,实例变量可以在内存中有多个拷贝,互不影响Q灵z)?/span>
2、静态方?/span>
静态方法可以直接通过cd调用QQ何的实例也都可以调用Q因此静态方法中不能?/span>this?/span>super关键字,不能直接讉K所属类的实例变量和实例Ҏ(是不带static的成员变量和成员成员Ҏ)Q只能访问所属类的静态成员变量和成员Ҏ。因为实例成员与特定的对象关联!q个需要去理解Q想明白其中的道理,不是记忆Q!Q?/span>
因ؓstaticҎ独立于Q何实例,因此staticҎ必须被实玎ͼ而不能是抽象?/span>abstract?/span>
3?/span>static代码?/span>
static代码块也叫静态代码块Q是在类中独立于cL员的static语句块,可以有多个,位置可以随便放,它不在Q何的Ҏ体内Q?/span>JVM加蝲cL会执行这些静态的代码块,如果static代码块有多个Q?/span>JVM按照它们在cM出现的先后顺序依ơ执行它们,每个代码块只会被执行一ơ?/span>
利用静态代码块可以对一?/span>static变量q行赋|最后再看一D些例子,都一?/span>static?/span>mainҎQ这?/span>JVM在运?/span>mainҎ的时候可以直接调用而不用创建实例?/span>
4?/span>static?/span>final一块用表示什?/span>
static final用来修饰成员变量和成员方法,可简单理解ؓ“全局帔R”Q?/span>
对于变量Q表CZ旦给值就不可修改Qƈ且通过cd可以讉K?/span>
对于ҎQ表CZ可覆盖,q且可以通过cd直接讉K?/span>
Z获取对象的一份拷贝,我们可以利用Objectcȝclone()Ҏ?br /> 在派生类中覆盖基cȝclone()ҎQƈ声明为public?br /> 在派生类的clone()Ҏ中,调用super.clone()?br /> 在派生类中实现Cloneable接口?/p>
Z么我们在zcM覆盖Object的clone()ҎӞ一定要调用super.clone()呢?在运行时刻,Object中的clone()识别Z要复制的是哪一个对象,然后为此对象分配I间Qƈq行对象的复Ӟ原始对象的内容一一复制到新对象的存储空间中?br />
Student s1 = new Student("gaoer", 14);
System.out.println("s1name=" + s1.getName());
Student s2 = s1; // 未用cloneQ他俩用一个地址Q?br />
s2.setAge(12);
s2.setName("zhangsan");
System.out.println("s1name=" + s1.getName());
Student s3 = (Student) s1.clone();
s3.setAge(12);
s3.setName("lisi");
System.out.println("s1name=" + s1.getName());
package l4;
/**
*
* @author Administrator
* 当没有引用类型的变量Ӟ为浅层次的拷?br />
*
*/
public class Student implements Cloneable {
private String name;
private int age;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
protected Object clone() throws CloneNotSupportedException {
Object o = null;
o = super.clone();
return o;
}
}
package l4;
/**
*
* @author Administrator
* 当没有引用类型的变量Ӟ为浅层次的克?br />
* 当有引用cd的变量时Qؓ深层ơ的克隆
*/
public class Student implements Cloneable {
private String name;
private int age;
Point pt;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
public Student(String name, int age,Point pt) {
this.name = name;
this.age = age;
this.pt = pt;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
protected Object clone() throws CloneNotSupportedException {
Student o = null;
o = (Student)super.clone();
o.pt = (Point)pt.clone();
return o;
}
}
package l4;
public class Point implements Cloneable {
public int x;
public int y;
@Override
public String toString() {
return "x=" + x + "y=" + y;
}
protected Object clone() throws CloneNotSupportedException {
Object o = null;
o = super.clone();
return o;
}
}
public static void change(int x, int y) {
x = x + y;
y = x - y;
x = x - y;
}
public static void change(int[] num) {
num[0] = num[0] + num[1];
num[1] = num[0] - num[1];
num[0] = num[0] - num[1];
}
public static void change(Point pt) {
pt.x = pt.x + pt.y;
pt.y = pt.x - pt.y;
pt.x = pt.x - pt.y;
}