java判断list对象数组里是否包含某个元素
时间: 2023-06-29 12:11:25 浏览: 77
你可以使用List的contains方法来判断一个元素是否在列表中。以下是示例代码:
```java
List<String> list = new ArrayList<>();
list.add("apple");
list.add("banana");
list.add("orange");
if (list.contains("apple")) {
System.out.println("List contains apple");
} else {
System.out.println("List does not contain apple");
}
```
如果你要判断的是自定义对象,需要在该对象中重写equals方法。例如,如果你有一个Person类:
```java
public class Person {
private String name;
private int age;
// 构造函数、getter和setter省略
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Person other = (Person) obj;
if (!Objects.equals(this.name, other.name)) {
return false;
}
if (this.age != other.age) {
return false;
}
return true;
}
}
```
你可以这样判断一个Person对象是否在列表中:
```java
List<Person> list = new ArrayList<>();
list.add(new Person("Alice", 20));
list.add(new Person("Bob", 30));
list.add(new Person("Charlie", 40));
Person targetPerson = new Person("Bob", 30);
if (list.contains(targetPerson)) {
System.out.println("List contains " + targetPerson.getName());
} else {
System.out.println("List does not contain " + targetPerson.getName());
}
```