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

键值不能重复，但可以多次赋值，取最后一次的值！

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;    }    }}