LinkedList类

LinkedList底层的数据结构是链表

链表相较于数组的优点：插入和删除时更加便捷，改变指针指向就行，不需要挪动位置
缺点：内存空间占用更大

添加数据add

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        System.out.println(list);//[zhangsan]
        System.out.println(list.getFirst());//zhangsan
        System.out.println(list.getLast());//zhangsan
    }
}

添加第二个数据

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        System.out.println(list);//[zhangsan]

//        list.add("lisi");//默认在后面加
//        System.out.println(list);//[zhangsan, lisi]
        list.addFirst("lisi");//在前面加
        System.out.println(list);//[lisi, zhangsan]
        System.out.println(list.getFirst());//lisi
        System.out.println(list.getLast());//zhangsan
    }
}

添加第三个数据

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        list.addFirst("lisi");//在前面加
//        list.addFirst("wangwu");//在最前面加
//        System.out.println(list);//[wangwu, lisi, zhangsan]
        list.add(1,"wangwu");//根据索引添加
        System.out.println(list);//[lisi, wangwu, zhangsan]
        System.out.println(list.getFirst());//lisi
        System.out.println(list.getLast());//zhangsan
    }
}

添加前后的索引变化，链表是没有索引的，java会根据数据的位置来构建索引

还有addAll，和ArrayList一样

获取数据get

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        list.addFirst("lisi");//在前面加
        list.add(1,"wangwu");//根据索引添加
        System.out.println(list);//[lisi, wangwu, zhangsan]
        System.out.println(list.get(1));//根据索引获取数据，wangwu
        System.out.println(list.getFirst());//获取第一个数据，lisi
        System.out.println(list.getLast());//获取最后一个数据，zhangsan
        //遍历
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
        System.out.println("---------------------------------");
        for (Object obj:list ){
            System.out.println(obj);
        }
    }
}

修改set

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        list.addFirst("lisi");//在前面加
        list.add(1,"wangwu");//根据索引添加
        System.out.println(list);//[lisi, wangwu, zhangsan]
        list.set(1,"zhaoliu");
        System.out.println(list);//[lisi, zhaoliu, zhangsan]
    }
}

删除remove

package List;

import java.util.LinkedList;

public class linkedList {
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add("zhangsan");
        list.addFirst("lisi");//在前面加
        list.add(1,"wangwu");//根据索引添加
        System.out.println(list);//[lisi, wangwu, zhangsan]
        list.remove("wangwu");
        System.out.println(list);//[lisi, zhangsan]
    }
}

list.remove()和list.removeFirst都是删除第一个数据