Java中的Set、List、Map、Stack简单举例

客官°小女子只卖身不卖艺 2021-09-30 03:08 242阅读 0赞

许久不写Java代码，许多基础性的东西都已经忘却了，今天写了几个关于Set、List、Map、Stack的小例子发布于此，以供自己以后参考~

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**1、首先定义几个实体类**

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**2、Map测试代码**

package com.xzw.test;
    
    import java.util.HashMap;
    import java.util.Map;
    import java.util.Map.Entry;
    import java.util.Set;
    
    import com.xzw.beans.Student;
    
    /**
     * 测试Map
     */
    
    public class TestMap {
        public static void main(String[] args) {
            Map map = new HashMap();
            map.put(100, new Student("张三", 12));
            map.put(200, new Student("李四", 13));
            map.put(300, new Student("王五", 15));
            map.put(400, new Student("赵六", 17));
            map.put(500, new Student("孙七", 18));
    
            Student stu1 = (Student) map.get(100);
            System.out.println(stu1.getName() + ":" + stu1.getAge());
            //是否包含这个key
            System.out.println(map.containsKey(1));
            //移除key对应的元素
            System.out.println(map.remove(500));
    
            System.out.println(map.size());
            //打印
            System.out.println(map.toString());
    
            //遍历
            Set keySet = map.keySet();
            for (Object key : keySet) {
                System.out.println(key + ": " + map.get(key));
            }
    
    
            Set entrySet = map.entrySet();
            for (Object entry : entrySet) {
                System.out.println(((Entry) entry).getKey() + ":" + ((Entry) entry).getValue());
            }
        }
    }

**3、List测试代码**

package com.xzw.test;
    
    import com.xzw.beans.Dog;
    
    import java.util.ArrayList;
    import java.util.Iterator;
    import java.util.LinkedList;
    
    /**
     * 测试List
     */
    
    public class TestList {
        /**
         * 测试ArrayList
         */
        public static void testArrayList() {
            ArrayList arrayList = new ArrayList();
            Dog dog = new Dog("欧欧", "雪纳瑞");
            Dog dog2 = new Dog("亚亚", "拉布拉多");
            Dog dog3 = new Dog("菲菲", "拉布拉多");
            Dog dog4 = new Dog("美美", "雪纳瑞");
    
            arrayList.add(dog);
            arrayList.add(dog2);
            arrayList.add(dog3);
            arrayList.add(3, dog3);  //指定位置添加
            arrayList.add(dog4);
    
            //删除第一条
            arrayList.remove(0);
            //删除指定的狗
            arrayList.remove(dog3);
    
            System.out.println("共有" + arrayList.size() + "条狗");
            System.out.println("分别是：");
    
            //是否包含
            System.out.println(arrayList.contains("亚亚"));
            //遍历
            Iterator iterator = arrayList.iterator();
            while (iterator.hasNext()) {
                System.out.println(iterator.next());
            }
    
            for (int i = 0; i < arrayList.size(); i++) {
                if (((Dog) arrayList.get(i)).getName().equals("美美")) {
                    System.out.println("集合中包含美美的信息");
                }
            }
    
            if (arrayList.contains(dog4)) {
                System.out.println("集合中包含" + dog4.getName() + "的信息");
            }
    
            //清空元素
            arrayList.clear();
            System.out.println(arrayList.isEmpty());
        }
    
        /**
         * 测试LinkedList
         */
        public static void testLinkedList() {
            LinkedList linkedList = new LinkedList();
            Dog dog = new Dog("欧欧", "雪纳瑞");
            Dog dog2 = new Dog("亚亚", "拉布拉多");
            Dog dog3 = new Dog("菲菲", "拉布拉多");
            Dog dog4 = new Dog("美美", "雪纳瑞");
    
            linkedList.addFirst(dog);
            linkedList.addLast(dog4);
            linkedList.addFirst(dog2);
            linkedList.addLast(dog3);
    
            System.out.println(linkedList);
            System.out.println("第一条狗的昵称：" + ((Dog) linkedList.get(0)).getName());
            System.out.println("最后一条狗的昵称：" + ((Dog) linkedList.get(linkedList.size() - 1)).getName());
    
            linkedList.removeFirst();
            linkedList.removeLast();
    
            System.out.println("剩下" + linkedList.size() + "条狗");
            System.out.println("分别是：");
            for (Object object : linkedList) {
                System.out.println(object);
            }
        }
    
        public static void main(String[] args) {
            long start = System.currentTimeMillis();
            new TestList().testArrayList();
            new TestList().testLinkedList();
            long end = System.currentTimeMillis();
            System.out.println("计算程序运行时间：" + (end-start));
        }
    }

**4、Set测试代码**

package com.xzw.test;
    
    import com.xzw.beans.Student;
    
    import java.util.HashSet;
    import java.util.Iterator;
    
    /**
     * 测试Set
     */
    
    public class TestSet {
        public static void main(String[] args) {
            HashSet hashSet = new HashSet();
            hashSet.add("1234");
            hashSet.add(new Student("xzw", 23));
            hashSet.add(new Student("xzw", 23));
            hashSet.add(new Student("xzw", 33));
            hashSet.add(new Student("xzw1", 33));
            hashSet.add(123);
            hashSet.add(true);
            //打印 （无序）
            System.out.println(hashSet);
            //hashset比较相同使用的是equals方法，相同的元素中只保存第一个
    
            //清空
            hashSet.clear();
            System.out.println(hashSet);
    
            //移除的时候也是使用equals进行比较
            hashSet.remove(new Student("xzw", 23));
            System.out.println(hashSet);
    
            //使用equals进行比较
            System.out.println(hashSet.contains(new Student("xzw", 13)));
    
            //遍历
            for (int i = 0; i < hashSet.size(); i++) {
                System.out.println();
            }
    
            for (Object object : hashSet) {
                System.out.println(object);
            }
    
            Iterator it = hashSet.iterator();
            while (it.hasNext()) {
                System.out.println(it.next());
            }
    
        }
    }

**5、Stack测试代码**

package com.xzw.test;
    
    import java.util.Stack;
    
    /**
     * 测试Stack
     */
    
    public class TestStack {
        public static void main(String[] args) {
            Stack stack = new Stack();
            //添加元素
            stack.push(12);
            stack.push(34);
            stack.push("test");
            stack.push(false);
            stack.push(31);
            System.out.println(stack);
    
            //查看栈顶元素
            System.out.println(stack.peek());
            //移除栈顶元素
            System.out.println(stack.pop());
        }
    }

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