System.out.println(i+"----->"+names.get(i));
}
//打印集合的大小
System.out.println("改变前的容器大小为:
"+names.size());
//删除集合中的第3个元素
System.out.println("删除的第三个元素为:
"+names.remove(3));
//打印目前集合中第3个元素的内容
System.out.println("第三个元素为:
"+names.get(3));
//打印集合的大小
System.out.println("改变后的容器大小为:
"+names.size());
}
publicstaticvoidmain(String[]args){
newDemoArrayList();
}
}
⑵
importjava.util.HashMap;
importjava.util.Map;
/**
*
(2)测试Map集合的基本使用
*
*@authorAdministrator
*
*/
publicclassDemoHashMap{
DemoHashMap(){
MapPerson=newHashMap();
Person.put("id","001");
Person.put("name","张三");
Person.put("sex","男");
Person.put("age","28");
Person.put("love","我爱Java");
//对集合进行遍历,分别打印集合中的每个元素的位置与内容;
System.out.println("id---->"+Person.get("id"));
System.out.println("name---->"+Person.get("name"));
System.out.println("sex---->"+Person.get("sex"));
System.out.println("age---->"+Person.get("age"));
System.out.println("love---->"+Person.get("love"));
//打印集合的大小
System.out.println("改变前的容器大小为:
"+Person.size());
//删除集合中的键为age的元素
System.out.println("刪除的值为:
"+Person.remove("age"));
//打印集合的大小
System.out.println("改变后的容器大小为:
"+Person.size());
}
publicstaticvoidmain(String[]args){
newDemoHashMap();
}
}
⑶
importjava.io.BufferedReader;
importjava.io.IOException;
importjava.io.InputStreamReader;
importjava.util.Iterator;
importjava.util.Vector;
/**
*测试Vector容器的基本用法
*
*@authorAdministrator1245
*/
publicclassDemoVector{
BufferedReaderbr=null;
/**
*获取一个Vector容器
*
*@return
*/
publicVectorgetVector(){
Stringstr;
//循环读入用户输入的字符串
br=newBufferedReader(newInputStreamReader(System.in));
Vectorvector=newVector();
try{
while(!
(str=br.readLine()).equals("end")){
vector.addElement(str);
}
}catch(IOExceptione){
e.printStackTrace();
}
System.out.println("-----------------------");
System.out.println("插入前容器的元素有:
");
showInfo(vector);
//在所有字符串的中间位置插入“NICE”
vector.insertElementAt("NICE",vector.size()/2);
returnvector;
}
/**
*遍历容器中的元素
*
*@paramv
*/
publicvoidshowInfo(Vectorv){
Iteratori=v.iterator();
while(i.hasNext()){
System.out.println(i.next());
}
}
publicstaticvoidmain(String[]args){
DemoVectordv=newDemoVector();
Vectorvector=dv.getVector();
System.out.println("-----------------------");
System.out.println("插入元素后容器的元素为:
");
dv.showInfo(vector);
}
}
⑷
/**
*测试泛型的使用接口
*
*@authorAdministrator
*
*/
interfaceShapeAreaPeri{
doublegetArea();
}
classTriangleimplementsShapeAreaPeri{
doublea,b,c;
Triangle(doublea,doubleb,doublec){
this.a=a;
this.b=b;
this.c=c;
}
publicdoublegetArea(){
doublerp=(a+b+c)/2.0;
returnMath.sqrt((rp-a)*(rp-b)*(rp-c));
}
}
classRectangleimplementsShapeAreaPeri{
doublewidth,length;
Rectangle(doublew,doublel){
width=w;
length=l;
}
publicdoublegetArea(){
returnwidth*length;
}
}
classCircleimplementsShapeAreaPeri{
doubleridus;
finaldoublepi=3.14;
Circle(doubler){
ridus=r;
}
publicdoublegetArea(){
returnpi*ridus*ridus;
}
}
publicclassTestGeneric{
publicvoidtest(ShapeAreaPeri
>sap){
System.out.println("所在图形的面积为:
"+sap.getArea());
}
publicstaticvoidmain(String[]args){
Trianglet=newTriangle(1.1,2.0,3.0);
Circlec=newCircle(1.2);
Rectangler=newRectangle(1.2,1.4);
TestGenerictg=newTestGeneric();
tg.test(t);
tg.test(c);
tg.test(r);
}
}
四、实验体会