addAll(Collection<? extends E> c)方法用于将指定 collection 中的所有元素添加到列表。
addAll(int index,Collection<? extends E> c );方法用于将指定 collection 中的所有元素添加到列表。同时,index指的是list下标，list下标是从0开始的.
数据类型案例:
List<String> list1 = new ArrayList<String>();
List<String> list2 = new ArrayList<String>();
list1.add("J");
list1.add("A");
list2.add("V");
list2.add("A");
list2.addAll(list1);
System.out.println("list2放在前面="+list2.toString());
List<String> list1 = new ArrayList<String>();
List<String> list2 = new ArrayList<String>();
list1.add("J");
list1.add("A");
list2.add("V");
list2.add("A");
list2.addAll(0, list1);
System.out.println("将list1放在前面="+list2.toString());
对象案例:
public class User {
private String name;
private Integer age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + "]";
}
public static void main(String[] args) {
List<User> user1 = new ArrayList<User>();
List<User> user2 = new ArrayList<User>();
User user3 = new User();
User user4 = new User();
user3.setName("java");
user3.setAge(24);
user4.setName("vue");
user4.setAge(6);
user1.add(user3);
user2.add(user4);
user1.addAll(user2);
//输出user1=[User [name=java, age=24], User [name=vue, age=6]]
//System.out.println("user1="+user1.toString());
//输出user1=[User [name=vue, age=6], User [name=java, age=24]]
user1.addAll(0,user2);
System.out.println("user1="+user1.toString());
}
}
