来京学习第11天

今天学习了集合类、泛型、时间和日历、枚举，还温故了Json解析xml文件，内容很多，但是都不深入！

List字符串排序

\\转载他人的
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class T {
public static void main(String[] args) {
ArrayList list = new ArrayList();
list.add("92.8");
list.add("68.9");
list.add("168.61");
list.add("242");
list.add("317");
list.add("105");
// 字符串排序
Collections.sort(list);
System.out.println(list.toString()); // [105, 168.61, 242, 317, 68.9, 92.8]
Collections.sort(list, new Comparator() {
@Override
public int compare(Object o1, Object o2) {
return new Double((String) o1).compareTo(new Double((String) o2));
}
});
System.out.println(list.toString()); // [68.9, 92.8, 105, 168.61, 242, 317]
}
}

我的JSON解析XML文件

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import net.sf.json.JSONArray;
import net.sf.json.JSONException;
import net.sf.json.JSONObject;

public class TestJSON {
public static void main(String[] args) {
File f=new File("d:\\a.txt");
BufferedWriter bw;
List list=new ArrayList();
try {
f.createNewFile();
//br=new BufferedReader(new FileReader(f));
String json=CreateJson();
bw=new BufferedWriter(new FileWriter(f));
bw.write(json);
bw.flush();//没有词句，文件没有被写入
JSONArray newArray = new JSONArray();
JSONObject newJson = new JSONObject();
//json遍历
if(json!=null){

JSONObject room=JSONObject.fromObject(json);//字符串获取一个json元素
Iterator it=room.keys();
newJson.put(it.next(), room.getString("num"));
newJson.put(it.next(), room.getString("sex"));

JSONArray array=room.getJSONArray("roommate");
for(int i=0;i<array.size();i++){
JSONObject obj=array.getJSONObject(i);//obj内原来已经有自己的key和对应的value
obj.put("exp", 20);
newArray.add(obj);
// System.out.println(obj.toString());
}
newJson.put("roommate", newArray);
System.out.println(newJson);

}

bw.close();
} catch (JSONException e) {
e.printStackTrace();
}  catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}

}

public static String CreateJson(){
/*JSONObject obj1=new JSONObject();
obj1.put("name", "han");
JSONObject obj2=new JSONObject();
obj2.put("name", "hong");
JSONObject obj3=new JSONObject();
obj3.put("name", "ling");
JSONArray array=new JSONArray();//json数组
array.add(obj1);
array.add(obj2);
array.add(obj3);
JSONObject obj=new JSONObject();
obj.put("num", "3人");
obj.put("roommate", array);//加入数组
System.out.println(obj.toString());
return obj.toString();*/
Person han=new Person(20,"han");
Person li=new Person(21,"li");
Person wan=new Person(22,"wan");
Person san=new Person(23,"san");
JSONObject obj=new JSONObject();
JSONArray array=new JSONArray();
array.add(han);
array.add(san);
array.add(wan);
array.add(li);
obj.put("num", "4人");
obj.put("sex", "女生");
obj.put("roommate", array);
//System.out.println(obj.toString());
return obj.toString();

}

}

转载他人的JSON解析

package com.hhl.xml0724;

import java.util.Iterator;

import net.sf.json.JSONArray;
import net.sf.json.JSONException;
import net.sf.json.JSONObject;

public class Test_JSON_Array {
public static void main(String[] args) {
String str = "{'TI':[{'value':'aa1','count':10},{'value':'aa3','count':20}]," +
"'AB':[{'value':'ab','count':110},{'value':'ab3','count':210}]}";
JSONArray newArray = new JSONArray();
JSONObject newJson = new JSONObject();
try {
JSONObject obj =JSONObject.fromObject(str);
Iterator it = obj.keys();
while (it.hasNext()) {
String key = (String) it.next();
//System.out.println(key);
String value = obj.getString(key);
//System.out.println(value);
JSONArray array = obj.getJSONArray(key);
for(int i=0;i<array.size();i++){
JSONObject jsonobject = array.getJSONObject(i);
//System.out.println(jsonobject);
jsonobject.put("name", key);
jsonobject.put("exp", key+"="+jsonobject.getString("value"));
newArray.add(jsonobject);
}
}
newJson.put("groups",newArray);
System.out.println(newJson);
} catch (JSONException e) {
e.printStackTrace();
}
}
}

Calendar类的使用

package com.hhl.xml0724;

import java.util.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;;

public class Test_Time_Calender {
public static void main(String[] args) {
Date da=new Date();
String st="yyyy/mm/dd kk:mm:ss";
SimpleDateFormat f=new SimpleDateFormat("yyyy-mm-dd kk:mm:ss");
//SimpleDateFormat f=new SimpleDateFormat();
Calendar ca=Calendar.getInstance();
System.out.println(da.getTime());//ms
System.out.println(ca.getTime());//cst 时间
System.out.println(f.format(da));//带格式输出 时间
System.out.println(da.toString());
System.out.println(ca.toString());//格林日历

System.out.println(da.getDate());//日
System.out.println(ca.get(Calendar.DAY_OF_MONTH));//日

System.out.println(da.getDay());//星期几
System.out.println(ca.get(Calendar.DAY_OF_WEEK));//
System.out.println(Calendar.HOUR_OF_DAY);//
//System.out.println(Calendar.DATE);//

ca.add( Calendar.HOUR_OF_DAY,2);//小时字段
System.out.println(ca.get(Calendar.HOUR_OF_DAY));//变化后的值
//f.format(da);
/*System.out.println(da.getDate());//
try {
Date date1=f.parse(st);
System.out.println(date1.getDate());
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}*/

}
}

集合类的练习

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class TestArraylist {
public static void main(String[] args) {
List<Person> list=new ArrayList<Person>();
Person han1=new Person(20,"han1");
Person han2=new Person(18,"han2");
Person han3=new Person(25,"han3");
Person han4=new Person(2,"han4");
Person han5=new Person(28,"han5");
Person han6=new Person(28,"han5");
Person han7=new Person(28,"han5");
list.add(han1);
list.add(han2);
list.add(han3);
list.add(han4);
list.add(han5);
list.add(han6);
list.add(3, han7);
list.get(2).setName("ling");
list.remove(0);
while(list.size()<8){
Person han8=new Person(28,"han5");
if(!list.contains(han8)){
list.add(han8);
}
}
Collections.sort(list, new MyComparator());
Collections.reverse(list对象);//反序
for(Person p:list){
System.out.println(p.getName()+" "+p.getAge());
}

}
}

import java.util.Comparator;

public class MyComparator implements Comparator<Person> {

@Override
public int compare(Person o1, Person o2) {
// TODO Auto-generated method stub
return o1.getAge()-o2.getAge();
}

}

HashSet练习

import java.util.HashSet;
import java.util.Iterator;
import java.util.Random;

public class TestHashSet {
public static void main(String[] args) {
HashSet<Integer> set=new HashSet<Integer>();
Random rand=new Random();
while(set.size()<10){
set.add(rand.nextInt(90)+10);
}
Iterator it=set.iterator();//对HashSet的遍历
while(it.hasNext()){
System.out.println(it.next());
}
System.out.println("the total is :"+set.size());
}

}

HashMap练习

package com.hhl.xml0724;

public class Person <T extends Animal>{
private T pet;
private Color color;

public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
public T getPet() {
return pet;
}
public void setPet(T pet) {
this.pet = pet;
}
private int age;
private String name;
public Person(int age,String name){
this.age=age;
this.name=name;
}
public Person(){}
public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;

public class TestHashMap {
public static void main(String[] args) {
HashMap<String,Person> mate=new HashMap<String,Person>();
Person han=new Person(20,"han");
Person li=new Person(20,"li");
Person wan=new Person(20,"wan");
Person san=new Person(20,"san");
mate.put("韩", han);
mate.put("李", li);
mate.put("王", wan);
mate.put("馓", san);
mate.put("馓", han);
Set<String> keys=mate.keySet();//键值集合
Iterator<String> it=keys.iterator();//集合遍历
while(it.hasNext()){
String str=it.next();
System.out.println(str+"  "+mate.get(str).getName());
}

}
}

泛型类练习

public class Animal {

}
public class Cat extends Animal{
private String name;
public Cat(){
System.out.println("我是Tom");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}
public class Cat extends Animal{
private String name;
public Cat(){
System.out.println("我是Tom");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}
public class Cat extends Animal{
private String name;
public Cat(){
System.out.println("我是Tom");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}
package com.hhl.xml0724;

public class Person <T extends Animal>{
private T pet;
private Color color;

public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
public T getPet() {
return pet;
}
public void setPet(T pet) {
this.pet = pet;
}
private int age;
private String name;
public Person(int age,String name){
this.age=age;
this.name=name;
}
public Person(){}
public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}

public class TestFanxin {
public static void main(String[] args) {
Person<Dog> han=new Person<Dog>();
Dog dog=new Dog();
han.setPet(dog);
Person<Cat> li=new Person<Cat>();
Cat cat=new Cat();
li.setPet(cat);
}
}

enum类练习

public enum Color {
RED,ORANGE,YELLOW,GREEN,PURPLE,BLACK,WHITE
}
public class TestEnum {
public static void main(String[] args) {
Person han=new Person();
han.setColor(Color.GREEN);
switch(han.getColor()){
case GREEN: System.out.println("綠衣服");break;
case RED:System.out.println("紅衣服");break;
case BLACK:System.out.println("黑衣服");break;
case PURPLE:System.out.println("紫衣服");break;
}

}
}