hashMap
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2022-06-04 19:17:37
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package hashMap;
import java.util.*;
import java.util.Map.Entry;
//map 是一种键值对 ，不能有重复的键 因此用set 作为其key最适合了
public class HashMapTest
{
public static <K, V> void main(String[] args)
{
// HashMap hm=new HashMap();
// hm.put(1,"123");
// hm.put(2,"456");
// hm.put(3,"123");
// hm.put(4,"456");
// hm.put(5,"123");
// hm.put(6,"456");
// System.out.println(hm.get(1));
// System.out.println(hm);
// //键试图操作
// Set s=hm.keySet();
// s.remove(1);
// System.out.println(hm);
// //值视图操作
// Collection col=hm.values();
// //col.add("789");
// col.remove("456");
// System.out.println(hm);
// //映射集合
// Set keyvalue=hm.entrySet();
// for(Object o:key_value)
// {
// Entry e=(Entry) o;
// e.setValue("test");
// System.out.println(e.getKey()+"------"+e.getValue());
// }
//hashMap与hashtable得区别:1.hashMap可以有空键，空值，hashtabe不可以有
//2.hashmap是线程不安全的，hashitable是线程安全的(单线程使用hashMap多线程使用hashtable)
//3.hashMap的效率高
HashMap<Integer, Manager> hm=new HashMap<Integer, Manager>();
Manager m1=new Manager(123,"郑云飞",22);
Manager m2=new Manager(456,"xuanzi",18);
hm.put(123, m1);
hm.put(456, m2);
if(hm.containsKey(123))
{
System.out.println("有此人");
Manager mm=m1;
System.out.println(mm);
}
else
{
System.out.println("无此人");
}
//遍历HashMap中的key何value的值
Iterator<Integer> it=hm.keySet().iterator();
while(it.hasNext())
{
//取出key
Integer key=it.next();
//通过key取出value
Manager mm=hm.get(key);
//输出信息
System.out.println("编号:"+mm.getId());
System.out.println("姓名:"+mm.getName());
System.out.println("年龄:"+mm.getAge());
}
}
}
package hashMap;
class Manager
{
private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
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;
}
public Manager(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public Manager(int id, String name)
{
super();
this.id = id;
this.name = name;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "编号:"+id+"姓名:"+name+"年龄："+age;
}
public static int test(int id,String name,int age)
{
System.out.println("编号:"+id+"姓名:"+name+"年龄："+age);
return age;
}
}
package hashMap;
import java.io.FileInputStream;
import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Properties;
class MyReflect
{
//依据参数返回类对象 参数:
public static Object getObject(String[] args,Class cl) throws Exception
{
int con_Args_Count = Integer.parseInt(args[1]);//构造函数参数个数
Class[] con_Class = new Class[con_Args_Count];//形参列表
Object[] con_Object = new Object[con_Args_Count];//实参列表
Object o = null;//获取对象的实例
for(int i=0;i<con_Class.length;i++)
{
if(args[2+i].equals("int"))
{
con_Class[i] = int.class;
con_Object[i] = Integer.parseInt(args[2+con_Args_Count+i]);
}
if(args[2+i].equals("String"))
{
con_Class[i] = String.class;
con_Object[i] = args[2+con_Args_Count+i];
}
if(args[2+i].equals("char"))
{
con_Class[i] = char.class;
con_Object[i] = args[2+con_Args_Count+i].charAt(0);
}
if(args[2+i].equals("float"))
{
con_Class[i] = float.class;
con_Object[i] = Float.parseFloat(args[2+con_Args_Count+i]);
}
if(args[2+i].equals("boolean"))
{
con_Class[i] = boolean.class;
con_Object[i] = Boolean.parseBoolean(args[2+con_Args_Count+i]);
}
}
Constructor con = cl.getDeclaredConstructor(con_Class);//获取class对象所表示的类或接口的指定构造方法
o = con.newInstance(con_Object);//创建对象
return o;
}
//依据参数执行方法 并返回结果 参数:
public static Object invokeMethod(String[] args,Object o,Class cl) throws Exception
{
int con_Args_Count = Integer.parseInt(args[1]);
int me_Args_Count = Integer.parseInt(args[3+2*con_Args_Count]);
Class[] me_Class = new Class[me_Args_Count];
Object[] me_Object = new Object[me_Args_Count];
String me_Name = args[2+2*con_Args_Count];
for(int i=0;i<me_Class.length;i++)
{
Object[] oo = turn(args[4+2*con_Args_Count+i],args[4+2*con_Args_Count+me_Args_Count+i]);
me_Class[i] = (Class)oo[0];
me_Object[i] = oo[1];
}
Method m = cl.getDeclaredMethod(me_Name,me_Class);
Object result = m.invoke(o,me_Object);
return result;
}
public static void main(String[] args) throws Exception
{
Properties p=new Properties();
p.load(new FileInputStream("test.ini"));
Enumeration e=p.propertyNames();
ArrayList al=new ArrayList();
while(e.hasMoreElements())
{
String key=(String) e.nextElement();
al.add(key);
}
Collections.sort(al);
}
public static Object[] turn(String cs,String os)
{
Object[] o = new Object[2];
if(cs.equals("int"))
{
o[0] = int.class;
o[1] = Integer.parseInt(os);
}
if(cs.equals("String"))
{
o[0] = String.class;
o[1] = os;
}
if(cs.equals("char"))
{
o[0] = char.class;
package hashMap;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Properties;
public class PropertiesTest
{
public static void main(String[] args) throws FileNotFoundException, IOException
{
Properties p=new Properties();
//Properties p=System.getProperties();
// System.out.println("当前系统:"+p.getProperty("os.name"));
// System.out.println("当前系统版本:"+p.getProperty("os.version"));
// System.out.println("当前java版本:"+p.getProperty("java.version"));
// System.out.println("用户名:"+p.getProperty("user.name"));
//
p.load(new FileInputStream("test.ini"));
//枚举器
Enumeration e=p.propertyNames();
while(e.hasMoreElements())
{
String key=(String) e.nextElement();
//为了能读中文()
System.out.println(key+"=="+new String(p.getProperty(key).getBytes("latin1"),"gbk"));
}
}
}
package hashMap;
import java.lang.reflect.*;
import java.io.*;
class ReflectTest
{
public static void main(String[] args) throws Exception
{
//BankCard bc=new BankCard("12","123456","zhangsan",123);
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
//获取待产生对象的类的名称
System.out.println("请输入类名:");
String className = br.readLine();
//加载该类至内存 并获得该类的自描述Class对象
Class cl = Class.forName(className);
//通过自描述对象产生对象（假如该类有无参构造）
Object o = cl.newInstance();
System.out.println(o.getClass().getName());
//获得待执行方法名
System.out.println("请输入方法名:");
String methodName = br.readLine();
//通过类的自描述对象获得方法的描述对象
if(methodName.equals("welcome"))
{
Method m = cl.getMethod(methodName);
m.invoke(o);
}
//通过方法的自描述对象执行该方法
//System.out.println("对象m："+m);
else if(methodName.equals("insertCard"))
{
Method m=cl.getMethod(methodName,BankCard.class);
m.invoke(o,bc);
}
/**
*调用主函数
*
**/
else if (methodName.equals("main"))
{
Method m = cl.getMethod(methodName,new Class[]{String[].class});
m.invoke(o,(Object)new String[]{"",""});
}
else if(methodName.equals("test"))
{
Method m=cl.getMethod(methodName,new Class[]{int.class,int.class});
m.invoke(o,5,6);
}
//获得一个类的所有公共非构造方法
System.out.println("All public method");
Method[] mo = cl.getMethods();
for(Method mm:mo)
{
System.out.println(mm);
}
System.out.println("All method:");
//获得一个类中所有非构造方法
Method[] me = cl.getDeclaredMethods();
for(Method mm:me)
{
System.out.println(mm);
}
//所有的公共构造
System.out.println("公共构造:");
Constructor[] c = cl.getConstructors();
for(Constructor cc:c)
{
System.out.println(cc);
}
//所有构造
System.out.println("所有构造:");
Constructor[] cs = cl.getDeclaredConstructors();
for(Constructor cs1:cs)
{
System.out.println(cs1);
}
}
};
class Test
{
int a,b;
Test(int a,int b)
{
this.a=a;
this.b=b;
}
public void test(int a,int b)
{
a=9;b=8;
System.out.println("a="+a+"b="+b);
//System.exit(0);
}
public void test(int a)
{
a=10;
System.out.println(a);
System.exit(0);
}
};
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