比较器比较 Java 中的 Int()和示例
原文:https://www . geesforgeks . org/comparator-comparingint-in-Java-with-examples/
comparingInt(Java . util . function . ToIntFunction)方法接受一个函数作为参数，该函数从类型 T 中提取一个 int 排序关键字，并返回一个按该排序关键字进行比较的比较器。如果指定的函数也是可序列化的，则返回的比较器是可序列化的。
语法:
static <T> Comparator<T> comparingInt(ToIntFunction <T> keyExtractor)
参数:该方法接受单个参数键提取器，该函数用于提取整数排序键。
返回值:该方法返回一个比较器，通过提取的键进行比较
异常:如果参数为空，此方法将引发 NullPointerException。
下面的程序说明了 comparingInt(Java . util . function . to intfunction)方法: 程序 1:
// Java program to demonstrate
// Comparator.comparingInt(java.util.function.ToIntFunction) method
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class GFG {
public static void main(String[] args)
{
// create some user objects
User u1 = new User("Aaman", 25);
User u2 = new User("Joyita", 22);
User u3 = new User("Suvam", 28);
User u4 = new User("mahafuj", 25);
// before sort
List<User> list
= Arrays.asList(u2, u1, u4, u3);
System.out.println("Before Sort:");
list.forEach(User
-> System.out.println("User age "
+ User.getAge()));
Collections.sort(list,
Comparator.comparingInt(
User::getAge));
System.out.println("\nAfterSort:");
list.forEach(User
-> System.out.println("User age "
+ User.getAge()));
}
}
class User implements Comparable<User> {
public String name;
public int age;
public User(String name, int age)
{
this.name = name;
this.age = age;
}
public int compareTo(User u1)
{
return name.compareTo(u1.name);
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public int getAge()
{
return age;
}
public void setAge(int age)
{
this.age = age;
}
@Override
public String toString()
{
return "User [name=" + name
+ ", age=" + age + "]";
}
}
打印在集成开发环境控制台上的输出如下所示。
输出:
程序 2:
// Java program to demonstrate
// Comparator.comparingInt(java.util.function.ToIntFunction) method
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class GFG {
public static void main(String[] args)
{
// before sort
List<Order> list = Arrays.asList(
new Order("A382y482y48", 320),
new Order("Vvekhfbkje2", 242),
new Order("efkhfbekjfbe", 1345),
new Order("bhdhdfaddvad", 230),
new Order("abkasbcjabjc", 100));
System.out.println("Before Sort:");
list.forEach(order -> System.out.println(order));
Collections.sort(list,
Comparator.comparingInt(
Order::getValue));
System.out.println("\nAfter Sort:");
list.forEach(order -> System.out.println(order));
}
}
class Order implements Comparable<Order> {
public String orderNo;
public int value;
public int compareTo(Order o1)
{
return orderNo.compareTo(o1.orderNo);
}
public Order(String orderNo, int value)
{
super();
this.orderNo = orderNo;
this.value = value;
}
@Override
public String toString()
{
return "Order [orderNo=" + orderNo
+ ", value=" + value + "]";
}
public String getOrderNo()
{
return orderNo;
}
public void setOrderNo(String orderNo)
{
this.orderNo = orderNo;
}
public int getValue()
{
return value;
}
public void setValue(int value)
{
this.value = value;
}
}
控制台上打印的输出如下所示。
输出:
参考文献:T2
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