实体类
import java.io.Serializable;
import java.util.Objects;
public class Person implements Serializable {
private static final long serialVersionUID = 1L;
private Integer id;
private String name;
private Integer age;
public Person(Integer id, String name, Integer age) {
this.id = id;
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
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 "Person{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + '}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Person person = (Person) o;
return Objects.equals(id, person.id);
}
@Override
public int hashCode() {
return Objects.hash(id);
}
}
数据预设定
| id | name | age |
|---|---|---|
| 100 | Sam1 | 12 |
| 101 | Sam2 | 13 |
| 102 | Sam3 | 14 |
| 103 | Sam4 | 15 |
| 104 | Sam5 | 16 |
| 105 | Sam6 | 17 |
| 106 | Sam7 | 18 |
| 107 | Sam8 | 19 |
| 108 | Sam9 | 20 |
优雅的List打印方式
list.forEach(System.out::println);
不知索引仍直接使用remove()
想直接remove()还不知索引，就需要按照equals()和hashCode()的指引，我们已经设定equals()的判据是id，也就是相当于把id当成了辨别人的唯一依据，那只需要构造一个id为指定值的对象，就能直接删了！
list.remove(new Person(101, "Bob", 333));
三种遍历时的删除方法
直接删
直接删注意index，如果删一个元素，其后一个元素的index就减一了，此时我们仍让i++，就会漏情况，所以要按下面说的写：
for (int i = 0; i < list.size();) {
if ("Sam5".equals(list.get(i).getName())) {
list.remove(i);
} else {
i++;
}
}
增强for循环删除
在这里面删元素，再遍历下去就是并发修改异常了，所以如果只删一个的话，赶紧break吧！
for (Person p : list) {
if ("Sam7".equals(p.getName())) {
list.remove(p);
break;
}
}
迭代器删除
获取List对象的迭代器，进行遍历。
删除使用iterator.remove()，能不出现并发修改异常，不需要一删除就break。
Iterator<Person> iterator = list.iterator();
while (iterator.hasNext()) {
Person p = iterator.next();
if ("Sam3".equals(p.getName())) {
iterator.remove();
}
}
完整代码
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class ListRemoveTest {
public static void main(String[] args) {
List<Person> list = new ArrayList<>();
list.add(new Person(100, "Sam1", 12));
list.add(new Person(101, "Sam2", 13));
list.add(new Person(102, "Sam3", 14));
list.add(new Person(103, "Sam4", 15));
list.add(new Person(104, "Sam5", 16));
list.add(new Person(105, "Sam6", 17));
list.add(new Person(106, "Sam7", 18));
list.add(new Person(107, "Sam8", 19));
list.add(new Person(108, "Sam9", 20));
System.out.println("**********************************************");
list.forEach(System.out::println);
System.out.println("**********************************************");
list.remove(new Person(101, "Bob", 333));
list.forEach(System.out::println);
System.out.println("**********************************************");
for (int i = 0; i < list.size();) {
if ("Sam5".equals(list.get(i).getName())) {
list.remove(i);
} else {
i++;
}
}
list.forEach(System.out::println);
System.out.println("**********************************************");
for (Person p : list) {
if ("Sam7".equals(p.getName())) {
list.remove(p);
break;
}
}
list.forEach(System.out::println);
System.out.println("**********************************************");
Iterator<Person> iterator = list.iterator();
while (iterator.hasNext()) {
Person p = iterator.next();
if ("Sam3".equals(p.getName())) {
iterator.remove();
}
}
list.forEach(System.out::println);
System.out.println("**********************************************");
}
}
测试结果
**********************************************
Person{id=100, name='Sam1', age=12}
Person{id=101, name='Sam2', age=13}
Person{id=102, name='Sam3', age=14}
Person{id=103, name='Sam4', age=15}
Person{id=104, name='Sam5', age=16}
Person{id=105, name='Sam6', age=17}
Person{id=106, name='Sam7', age=18}
Person{id=107, name='Sam8', age=19}
Person{id=108, name='Sam9', age=20}
**********************************************
Person{id=100, name='Sam1', age=12}
Person{id=102, name='Sam3', age=14}
Person{id=103, name='Sam4', age=15}
Person{id=104, name='Sam5', age=16}
Person{id=105, name='Sam6', age=17}
Person{id=106, name='Sam7', age=18}
Person{id=107, name='Sam8', age=19}
Person{id=108, name='Sam9', age=20}
**********************************************
Person{id=100, name='Sam1', age=12}
Person{id=102, name='Sam3', age=14}
Person{id=103, name='Sam4', age=15}
Person{id=105, name='Sam6', age=17}
Person{id=106, name='Sam7', age=18}
Person{id=107, name='Sam8', age=19}
Person{id=108, name='Sam9', age=20}
**********************************************
Person{id=100, name='Sam1', age=12}
Person{id=102, name='Sam3', age=14}
Person{id=103, name='Sam4', age=15}
Person{id=105, name='Sam6', age=17}
Person{id=107, name='Sam8', age=19}
Person{id=108, name='Sam9', age=20}
**********************************************
Person{id=100, name='Sam1', age=12}
Person{id=103, name='Sam4', age=15}
Person{id=105, name='Sam6', age=17}
Person{id=107, name='Sam8', age=19}
Person{id=108, name='Sam9', age=20}
**********************************************
