Java入门学习笔记（十）——泛型和反射、常用泛型类、ArryList类、LinkedList类、Stack类、HashSet类、TreeSet类

超、凢脫俗 2022-12-11 13:51 14阅读 0赞

# 一、常用的泛型类 #

## 1.ArrayList类 ##

package try_a_package;
    
    import java.util.ArrayList;
    
    class ArrayListTest {
        
    	public static void main(String[] args)
    	{
        
    		ArrayList list1=new ArrayList();
    		list1.add("我是一个");
    		list1.add("憨憨");
    		list1.add(1);
    		boolean flag1=list1.contains("憨憨");
    		if(flag1)
    			System.out.println("我是憨憨");
    		else
    			System.out.println("我才不是憨憨呢！");
    		System.out.println(list1.get(0));
    		System.out.println(list1.size());
    		System.out.println(list1.set(0, "我是两个"));
    		for(Object a:list1)
    		{
        
    			System.out.println(a);
    		}
    		// 这里像删除的元素，而不少索引，所以增加了Object的类型转换来实现这个操作。
    		list1.remove((Object)1);
    		// 如果不加Object的话，会直接移除索引处的元素
    		// 如果索引处的元素，不存在，如下面这个删除Object后的情形
    		// 则会抛出越界的异常
    		list1.remove((Object)2);
    		for(int i=0;i<list1.size();++i)
    		{
        
    			Object o=list1.get(i);
    			System.out.println(o);
    		}
    		System.out.println(list1.isEmpty());
    		System.out.println(list1.indexOf("憨憨"));
    		list1.clear();
    		System.out.println(list1.isEmpty());
    	}
    }

## 2.LinkedList类 ##

package try_a_package;
    
    import java.util.LinkedList;
    
    public class LinkedListTest {
        
    	public static void main(String[] args) {
        
    		// 构造
    		LinkedList list = new LinkedList();
    		// 插入元素
    		list.add(4);
    		list.add("String");
    		list.add(1, 5);
    		list.addFirst(1);
    		list.addLast(8);
    		// 读取指定元素
    		System.out.println(list.getFirst());
    		System.out.println(list.getLast());
    		System.out.println(list.get(2));
    		int temp = list.indexOf(5);
    		System.out.println(temp);
    		temp = list.lastIndexOf(5);
    		System.out.println(temp);
    		// 注意，要进行强制类型
    		temp = (int) list.peek();
    		System.out.println(temp);
    		// 移除元素
    		temp = (int) list.poll();
    		System.out.println(temp);
    		temp = (int) list.remove();
    		System.out.println(temp);
    		temp = (int) list.get(0);
    		System.out.println(temp);
    		String str = (String) list.get(1);
    		System.out.println(str);
    		str = (String) list.remove(1);
    		System.out.println(str);
    		boolean flag = list.remove((Object) 5);
    		System.out.println(flag);
    		flag = list.remove((Object) 5);
    		System.out.println(flag);
    		temp = (int) list.removeFirst();
    		System.out.println(temp);
    		if (!list.isEmpty())
    			temp = (int) list.removeLast();
    		System.out.println(temp);
    	}
    }

## 3.Stack类 ##

package try_a_package;
    
    import java.util.Stack;
    import java.util.Scanner;
    
    public class StackTest {
        
    	public static void main(String[] args)
    	{
        
    		Stack stack=new Stack();
    		Scanner sc=new Scanner(System.in,"gbk");
    		stack.push(1);
    		stack.push(2);
    		stack.push(5);
    		while(!stack.isEmpty())
    		{
        
    			System.out.println(stack.pop());
    		}
    		sc.close();
    	}
    }

## 4.HashSet类 ##

package try_a_package;
    
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.Random;
    
    public class HashSetTest {
        
    	// 输出集合中的元素
    	public static void print(HashSet a)
    	{
        
    		System.out.print("{");
    		Iterator it=a.iterator();
    		int c=0;
    		while(it.hasNext())
    		{
        
    			int t=(int)it.next();
    			if(c==0)
    			{
        
    				System.out.print(t);
    			}
    			else
    			{
        
    				System.out.print(","+t);
    			}
    			c++;
    		}
    		System.out.println("}");
    	}
    	// 合并两个集合
    	public static HashSet interSection(HashSet a,HashSet b)
    	{
        
    		HashSet c=new HashSet();
    		Iterator it=a.iterator();
    		while(it.hasNext())
    		{
        
    			int t=(int)it.next();
    			if(b.contains(t))
    			{
        
    				c.add(t);
    			}
    		}
    		return c;
    	}
    	// 求并集
    	public static HashSet unionSection(HashSet a,HashSet b)
    	{
        
    		HashSet c=new HashSet(a);
    		c.addAll(b);
    		return c;
    	}
    	// 随机生成元素，构成集合
    	public static HashSet getSet(int num,int n)
    	{
        
    		HashSet h=new HashSet();
    		Random rd=new Random();
    		for(int i=0;i<n;++i)
    		{
        
    			int now_rd=rd.nextInt(num);
    			h.add(now_rd);
    		}
    		return h;
    	}
    	// 主函数
    	public static void main(String[] args)
    	{
        
    		HashSet a,b,c,d;
    		a=getSet(10,6);
    		b=getSet(10,6);
    		print(a);
    		print(b);
    		c=interSection(a,b);
    		d=unionSection(a,b);
    		print(c);
    		print(d);
    	}
    }

![在这里插入图片描述][20201004191241893.png_pic_center]

## 5.TreeSet ##

package try_a_package;
    
    import java.util.Collection;
    import java.util.Iterator;
    import java.util.Random;
    import java.util.TreeSet;
    
    public class TreeSetTest {
        
    	// 输出集合中的所有元素（适用于List,Queue,Set）
    	public static void printSet(Collection a)
    	{
        
    		System.out.print("(");
    		Iterator it=a.iterator();
    		for(int i=0;it.hasNext();++i)
    		{
        
    			int t=(int)it.next();
    			if(i==0)
    			{
        
    				System.out.print(t);
    			}
    			else
    			{
        
    				System.out.print(","+t);
    			}
    		}
    		System.out.println("}");
    	}
    	// 输出ENode构成的集合中的元素
    	public static void print(TreeSet<ENode> ts)
    	{
        
    		System.out.println("输出集合中的元素:");
    		System.out.println("{");
    		Iterator it=ts.iterator();
    		while(it.hasNext())
    		{
        
    			ENode node=(ENode)it.next();
    			System.out.println(node);
    		}
    		System.out.println("}\n");
    	}
    	// 随机产生由n个元素构成的集合
    	public static TreeSet getTreeSet(int num,int n)
    	{
        
    		TreeSet h=new TreeSet();
    		Random rd=new Random();
    		for(int i=0;i<n;++i)
    		{
        
    			int tmp=rd.nextInt(num);
    			h.add(tmp);
    		}
    		return h;
    	}
    	
    	public static TreeSet<ENode> getDecare(TreeSet a,TreeSet b)
    	{
        
    		TreeSet<ENode> ts=new TreeSet<>();
    		Iterator ita;
    		ita=a.iterator();
    		while(ita.hasNext())
    		{
        
    			int tmpa=(int)ita.next();
    			Iterator itb=b.iterator();
    			while(itb.hasNext())
    			{
        
    				int tmpb=(int) itb.next();
    				ENode node=new ENode(tmpa,tmpb);
    				ts.add(node);
    			}
    		}
    		return ts;
    	}
    	
    	// 主函数
    	public static void main(String[] args)
    	{
        
    		TreeSet a,b;
    		a=getTreeSet(10,3);
    		b=getTreeSet(10,2);
    		printSet(a);
    		printSet(b);
    		TreeSet<ENode> c=getDecare(a,b);
    		print(c);
    	}
    }

![在这里插入图片描述][20201004201603244.png_pic_center]

## 6.HashMap ##

### Vote ###

package try_a_package;
    
    public class Vote {
        
    	private String voterNames;
    	private int count;
    	@Override
    	public String toString()
    	{
        
    		return "得票数量:"+count+"\n投票人列表:"+voterNames;
    	}
    	
    	public Vote()
    	{
        
    		voterNames="";
    		count=0;
    	}
    	
    	public String getVoterNames()
    	{
        
    		return voterNames;
    	}
    	
    	public int getCount()
    	{
        
    		return count;
    	}
    	
    	public void increase(String voterName)
    	{
        
    		this.voterNames=this.voterNames+","+voterName;
    		this.count++;
    	}
    }

### HashMapTest ###

package try_a_package;
    
    import java.util.HashMap;
    import java.util.Scanner;
    import java.util.Random;
    
    public class HashMapTest {
        
    	 public static void main(String[] args)
    	 {
        
    		 // 初始化HashMap
    		 HashMap<String,Vote> pollsMap=new HashMap<>();
    		 // 初始化候选人数组
    		 String condidateNames[]= {
        "张三","李四","王昭光"};
    		 Vote vote;
    		 // 初始化投票情况?
    		 for(int i=0;i<condidateNames.length;++i)
    		 {
        
    			 vote=new Vote();
    			 pollsMap.put(condidateNames[i], vote);
    		 }
    		 int number;
    		 String voter[];
    		 Scanner sc=new Scanner(System.in,"gbk");
    		 System.out.println("输入投票人数：");
    		 number=sc.nextInt();
    		 sc.close();
    		 voter=new String[number];
    		 for(int i=0;i<number;++i)
    		 {
        
    			 voter[i]="v"+(i+1);
    		 }
    		 Random rd=new Random();
    		 for(int i=0;i<number;++i)
    		 {
        
    			 int select=rd.nextInt(condidateNames.length);
    			 Vote value=pollsMap.get(condidateNames[select]);
    			 value.increase(voter[i]);
    			 pollsMap.put(condidateNames[select], value);
    		 }
    		 // 结果显示
    		 for(int i=0;i<condidateNames.length;++i)
    		 {
        
    			 System.out.println("候选人："+condidateNames[i]+":");
    			 Vote value=pollsMap.get(condidateNames[i]);
    			 System.out.println(value);
    		 }
    	 }
    }

### 运行结果 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTYzMjcw_size_16_color_FFFFFF_t_70_pic_center]

# 二、与反射相关的类 #

## 1. Modifier类 ##

// 基本类
    	// (1)修饰符Modifier类
    	//依据修饰符代码值得到修饰符串
    	public static String getModifierStr(int mod)
    	{
        
    		String msg="";
    		if(Modifier.isPublic(mod))
    		{
        
    			msg+=" public";
    		}
    		if(Modifier.isPrivate(mod))
    		{
        
    			msg+=" private";
    		}
    		if(Modifier.isStatic(mod))
    		{
        
    			msg+=" static";
    		}
    		if(Modifier.isSynchronized(mod))
    		{
        
    			msg+=" synchronized";
    		}
    		if(Modifier.isStrict(mod))
    		{
        
    			msg+=" strict";
    		}
    		if(Modifier.isAbstract(mod))
    		{
        
    			msg+=" abstract";
    		}
    		if(Modifier.isTransient(mod))
    		{
        
    			msg+=" transient";
    		}
    		if(Modifier.isVolatile(mod))
    		{
        
    			msg+=" volatile";
    		}
    		if(Modifier.isFinal(mod))
    		{
        
    			msg +=" final";
    		}
    		return msg;
    	}

## 2. Field类 ##

// (2)Field类 
    	// 输出一个成员属性
    	public static void outputField(Field fs)
    	{
        
    		String msg;
    		int modifiers =fs.getModifiers();
    		// 属性修饰符
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		// 属性的数据类型
    		Type tp=fs.getType();
    		// 属性的名称
    		System.out.println(tp+" "+fs.getName()+";");
    	}

## 3. constructor类 ##

// (3)Constructor类
    	// 输出一个构造方法
    	public static void outputConstructor(Constructor constructor)
    	{
        
    		String msg;
    		int modifiers=constructor.getModifiers();
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		System.out.print(constructor.getName()+"(");
    		Type tps[]=constructor.getParameterTypes();
    		for(int i=0;i<tps.length;++i)
    		{
        
    			if(i!=0)
    			{
        
    				System.out.print(",");
    			}
    			System.out.print(tps[i]+" "+(char)('a'+i));
    		}
    		System.out.println(");");
    	}

## 4. Method类 ##

// (4)Method类
    	// 输出一个方法
    	public static void outputMethod(Method ms)
    	{
        
    		String msg;
    		int modifiers=ms.getModifiers();
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		System.out.print(ms.getReturnType().getCanonicalName()+" ");
    		System.out.print(ms.getName()+"(");
    		Type tps[]=ms.getGenericParameterTypes();
    		for(int i=0;i<tps.length;++i)
    		{
        
    			if(i!=0)
    			{
        
    				System.out.print(",");
    			}
    			System.out.print(tps[i]+" "+(char)('a'+i));
    		}
    		System.out.print(");");
    	}

## 5. Class类 ##

// (5)Class类
    	// 5.1 输出类或接口定义的部分信息
    	public static void outputMsgOfClass(Class c)
    	{
        
    		String msg="";
    		// 得到修饰符的编码值
    		int modifiers=c.getModifiers();
    		msg=getModifierStr(modifiers);
    		if(c.isInterface())
    		{
        
    			msg+=" interface";
    		}
    		else if(c.isEnum())
    		{
        
    			msg+=" enum";
    		}
    		else
    		{
        
    			msg+=" class";
    		}
    		System.out.print(msg);
    		// 得到父类信息
    		Class parent=c.getSuperclass();
    		Object ob=new Object();
    		Class obc=ob.getClass();
    		if(parent!=null && parent.getCanonicalName().compareTo(obc.getName())!=0)
    		{
        
    			System.out.print("extends" + parent.getCanonicalName());
    		}
    		// 得到接口数组
    		Class[] interfaces=c.getInterfaces();
    		for(int i=0;i<interfaces.length;++i)
    		{
        
    			if(i==0)
    			{
        
    				System.out.print(" implements "+interfaces[i].getName());
    			}
    			else
    			{
        
    				System.out.print(" "+interfaces[i].getName());
    			}
    		}
    		System.out.println("{");
    	}
    	
    	// 5.2 输出类中的所有属性
    	public static void outputFields(Class c)
    	{
        
    		Field fs[];
    		fs=c.getDeclaredFields();
    		for(int i=0;i<fs.length;++i)
    		{
        
    			outputField(fs[i]);
    		}
    	}
    	
    	// 5.3 输出类中的所有构造方法
    	public static void outputConstructors(Class c)
    	{
        
    		Constructor constructors[];
    		constructors=c.getDeclaredConstructors();
    		for(Constructor constructor:constructors)
    		{
        
    			outputConstructor(constructor);
    		}
    	}
    	
    	// 5.4 输出类中声明的所有方法
    	public static void outputMethods(Class c)
    	{
        
    		Method ms[];
    		ms=c.getDeclaredMethods();
    		for(int i=0;i<ms.length;++i)
    		{
        
    			outputMethod(ms[i]);
    		}
    	}
    	
    
    	// 5.5 输出类的所有信息，包括超类的信息
    	public static void outputAllInformationOfClass(Class c) throws Exception
    	{
        
    		Class parent=c.getSuperclass();
    		Object ob=new Object();
    		Class obc=ob.getClass();
    		if(parent!=null && parent.getName().compareTo(obc.getName())!=0)
    		{
        
    			outputAllInformationOfClass(parent);
    		}
    		String msg;
    		if(c.isInterface())
    		{
        
    			msg="接口";
    		}
    		else if(c.isEnum())
    		{
        
    			msg="枚举";
    		}
    		else
    		{
        
    			msg="类";
    		}
    		System.out.println("反射"+c.getCanonicalName()+msg);
    		System.out.println("-----------------------------");
    		outputMsgOfClass(c);
    		outputFields(c);
    		outputConstructors(c);
    		outputMethods(c);
    		System.out.println("}");
    		//outputInterfaces(c);
    	}

## 6. 测试类（随便选择，无需看） ##

package try_a_package;
    
    public class Triangle1 {
        
    	private double a,b,c;
    	String name="三角形";
    	
    	public Triangle1()
    	{
        
    		this(10);
    	}
    	
    	public Triangle1(double x)
    	{
        
    		this(x,x,x);
    	}
    	
    	public Triangle1(double x,double y)
    	{
        
    		this(x,x,y);
    	}
    	
    	public Triangle1(double a,double b,double c)
    	{
        
    		this.a=a;
    		this.b=b;
    		this.c=c;
    		adjustName();
    	}
    	
    	public void adjustName()
    	{
        
    		if(this.isTriangle())
    		{
        
    			double  t;
    			if(a>b)
    			{
        
    				t=a;
    				a=b;
    				b=t;
    			}
    			if(a>c)
    			{
        
    				t=a;
    				a=c;
    				c=t;
    			}
    			if(b>c)
    			{
        
    				t=b;
    				b=c;
    				c=t;
    			}
    			name="三角形";
    			if(c*c==a*a+b*b)
    			{
        
    				name="直角"+name;
    			}
    			else if(a==b&&b==c)
    			{
        
    				name="等边"+name;
    			}
    			else if(a==b||b==c)
    			{
        
    				name="等腰"+name;
    			}
    		}
    		else
    		{
        
    			name="非三角形";
    		}
    	}
    	
    	public boolean isTriangle()
    	{
        
    		if(a+b>c && a+c>b && b+c>a)
    		{
        
    			return true;
    		}
    		return false;
    	}
    	
    	public double    getPerimeter()
    	{
        
    		return a+b+c;
    	}
    	
    	public double getArea()
    	{
        
    		double p,s;
    		p=(a+b+c)/2;
    		s=Math.sqrt(p*(p-a)*(p-b)*(p-c));
    		return s;
    	}
    	
    	@Override
    	public String toString()
    	{
        
    		String msg=name+"\t"+a+"\t"+b+"\t"+c;
    		if(isTriangle())
    		{
        
    			msg=msg+"\t"+this.getPerimeter()+"\t"+this.getArea();
    		}
    		return msg;
    	}
    	
    	public static void printHeader()
    	{
        
    		System.out.println("图形名称\t\t边长a\t边长b\t边长c\t周长\t面积");
    	}
    }

## 7. 完整测试程序（可以执行） ##

package try_a_package;
    
    import java.lang.reflect.Constructor;
    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    import java.lang.reflect.Modifier;
    import java.lang.reflect.Type;
    
    public class Reflect {
        
    	// 基本类
    	// (1)修饰符Modifier类
    	//依据修饰符代码值得到修饰符串
    	public static String getModifierStr(int mod)
    	{
        
    		String msg="";
    		if(Modifier.isPublic(mod))
    		{
        
    			msg+=" public";
    		}
    		if(Modifier.isPrivate(mod))
    		{
        
    			msg+=" private";
    		}
    		if(Modifier.isStatic(mod))
    		{
        
    			msg+=" static";
    		}
    		if(Modifier.isSynchronized(mod))
    		{
        
    			msg+=" synchronized";
    		}
    		if(Modifier.isStrict(mod))
    		{
        
    			msg+=" strict";
    		}
    		if(Modifier.isAbstract(mod))
    		{
        
    			msg+=" abstract";
    		}
    		if(Modifier.isTransient(mod))
    		{
        
    			msg+=" transient";
    		}
    		if(Modifier.isVolatile(mod))
    		{
        
    			msg+=" volatile";
    		}
    		if(Modifier.isFinal(mod))
    		{
        
    			msg +=" final";
    		}
    		return msg;
    	}
    	
    	
    	// (2)Field类 
    	// 输出一个成员属性
    	public static void outputField(Field fs)
    	{
        
    		String msg;
    		int modifiers =fs.getModifiers();
    		// 属性修饰符
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		// 属性的数据类型
    		Type tp=fs.getType();
    		// 属性的名称
    		System.out.println(tp+" "+fs.getName()+";");
    	}
    	
    	
    	// (3)Constructor类
    	// 输出一个构造方法
    	public static void outputConstructor(Constructor constructor)
    	{
        
    		String msg;
    		int modifiers=constructor.getModifiers();
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		System.out.print(constructor.getName()+"(");
    		Type tps[]=constructor.getParameterTypes();
    		for(int i=0;i<tps.length;++i)
    		{
        
    			if(i!=0)
    			{
        
    				System.out.print(",");
    			}
    			System.out.print(tps[i]+" "+(char)('a'+i));
    		}
    		System.out.println(");");
    	}
    	
    	
    	// (4)Method类
    	// 输出一个方法
    	public static void outputMethod(Method ms)
    	{
        
    		String msg;
    		int modifiers=ms.getModifiers();
    		msg=getModifierStr(modifiers);
    		System.out.print(msg+" ");
    		System.out.print(ms.getReturnType().getCanonicalName()+" ");
    		System.out.print(ms.getName()+"(");
    		Type tps[]=ms.getGenericParameterTypes();
    		for(int i=0;i<tps.length;++i)
    		{
        
    			if(i!=0)
    			{
        
    				System.out.print(",");
    			}
    			System.out.print(tps[i]+" "+(char)('a'+i));
    		}
    		System.out.print(");");
    	}
    	
    	// (5)Class类
    	// 5.1 输出类或接口定义的部分信息
    	public static void outputMsgOfClass(Class c)
    	{
        
    		String msg="";
    		// 得到修饰符的编码值
    		int modifiers=c.getModifiers();
    		msg=getModifierStr(modifiers);
    		if(c.isInterface())
    		{
        
    			msg+=" interface";
    		}
    		else if(c.isEnum())
    		{
        
    			msg+=" enum";
    		}
    		else
    		{
        
    			msg+=" class";
    		}
    		System.out.print(msg);
    		// 得到父类信息
    		Class parent=c.getSuperclass();
    		Object ob=new Object();
    		Class obc=ob.getClass();
    		if(parent!=null && parent.getCanonicalName().compareTo(obc.getName())!=0)
    		{
        
    			System.out.print("extends" + parent.getCanonicalName());
    		}
    		// 得到接口数组
    		Class[] interfaces=c.getInterfaces();
    		for(int i=0;i<interfaces.length;++i)
    		{
        
    			if(i==0)
    			{
        
    				System.out.print(" implements "+interfaces[i].getName());
    			}
    			else
    			{
        
    				System.out.print(" "+interfaces[i].getName());
    			}
    		}
    		System.out.println("{");
    	}
    	
    	// 5.2 输出类中的所有属性
    	public static void outputFields(Class c)
    	{
        
    		Field fs[];
    		fs=c.getDeclaredFields();
    		for(int i=0;i<fs.length;++i)
    		{
        
    			outputField(fs[i]);
    		}
    	}
    	
    	// 5.3 输出类中的所有构造方法
    	public static void outputConstructors(Class c)
    	{
        
    		Constructor constructors[];
    		constructors=c.getDeclaredConstructors();
    		for(Constructor constructor:constructors)
    		{
        
    			outputConstructor(constructor);
    		}
    	}
    	
    	// 5.4 输出类中声明的所有方法
    	public static void outputMethods(Class c)
    	{
        
    		Method ms[];
    		ms=c.getDeclaredMethods();
    		for(int i=0;i<ms.length;++i)
    		{
        
    			outputMethod(ms[i]);
    		}
    	}
    	
    
    	// 5.5 输出类的所有信息，包括超类的信息
    	public static void outputAllInformationOfClass(Class c) throws Exception
    	{
        
    		Class parent=c.getSuperclass();
    		Object ob=new Object();
    		Class obc=ob.getClass();
    		if(parent!=null && parent.getName().compareTo(obc.getName())!=0)
    		{
        
    			outputAllInformationOfClass(parent);
    		}
    		String msg;
    		if(c.isInterface())
    		{
        
    			msg="接口";
    		}
    		else if(c.isEnum())
    		{
        
    			msg="枚举";
    		}
    		else
    		{
        
    			msg="类";
    		}
    		System.out.println("反射"+c.getCanonicalName()+msg);
    		System.out.println("-----------------------------");
    		outputMsgOfClass(c);
    		outputFields(c);
    		outputConstructors(c);
    		outputMethods(c);
    		System.out.println("}");
    		//outputInterfaces(c);
    	}
    	
    	
    	// 主程序
    	public static void main(String[] args) throws Exception
    	{
        
    		Class c=null;
    		c=Class.forName("try_a_package.Triangle1");
    		outputAllInformationOfClass(c);
    		Triangle1 t=null;
    		c=Class.forName("try_a_package.Triangle1");
    		System.out.println("创建Triangle1类的默认实例");
    		t=(Triangle1)c.newInstance();
    		t.adjustName();
    		t.printHeader();
    	}
    }

## 8.运行结果 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTYzMjcw_size_16_color_FFFFFF_t_70_pic_center 1]

反射try\_a\_package.Triangle1类  
\-----------------------------  
public class\{  
private double a;  
private double b;  
private double c;  
class java.lang.String name;  
public try\_a\_package.Triangle1(double a,double b,double c);  
public try\_a\_package.Triangle1(double a,double b);  
public try\_a\_package.Triangle1(double a);  
public try\_a\_package.Triangle1();  
public java.lang.String toString(); public static void printHeader(); public void adjustName(); public boolean isTriangle(); public double getPerimeter(); public double getArea();\}  
创建Triangle1类的默认实例  
图形名称 边长a 边长b 边长c 周长 面积

[20201004191241893.png_pic_center]: /images/20221123/e8f88652789849beb57f4139e841993a.png
[20201004201603244.png_pic_center]: /images/20221123/59fcb0848a2649d6a6e4a2714e55b857.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTYzMjcw_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/45670b7f67404542b3d32e8cccdf8201.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTYzMjcw_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/b4a6543bdd824036a3ad0862665e46c0.png