1:LinkedList 请用LinkedList模拟栈数据结构的集合,并测试
package day17;
import java.util.LinkedList;
public class MyStack {
private LinkedList linkedList;
public MyStack(){
linkedList = new LinkedList();
}//构造函数一开始就创建一个LinkedList
public void add(Object object){
linkedList.addFirst(object);
}//添加方法
public Object get(){//获取方法
// return linkedList.getFirst();
return linkedList.removeFirst();
}
public boolean isEmpty(){
return linkedList.isEmpty();
}//判断栈是否为空
}
package day17;
public class MyStackTest {
public static void main(String[] args) {
//创建集合对象
MyStack myStack = new MyStack();
//添加元素
myStack.add("hello");
myStack.add("world");
myStack.add("bigdata");
// System.out.println(myStack.get());
// System.out.println(myStack.get());
// System.out.println(myStack.get());
// System.out.println(myStack.get()); //NoSuchElementException
//模拟出栈
while (!myStack.isEmpty()){
Object o = myStack.get();
String s = (String)o;
System.out.println(s);
}
}
}
2:集合的嵌套遍历
package day27;
import java.util.ArrayList;
public class Test12 {
public static void main(String[] args) {
ArrayList arrayLists = new ArrayList();//创建一个ArrayList对象
ArrayList<String> strings = new ArrayList<String >();//创建一个ArrayList对象并且指定类型为String
//向集合strings中添加元素
strings.add("hello");
strings.add("world");
//向集合arrayLists添加元素
arrayLists.add(strings);
arrayLists.add("java");
//增强for循环遍历strings集合
for (String string : strings) {
System.out.println(string);
}
System.out.println("==========================================");
//增强for循环遍历arrayList集合
for (Object arrayList : arrayLists) {
System.out.println(arrayList);
}
}
}