Java ZoneOffset compareTo(ZoneOffset)方法及示例

java.time包中ZoneOffset类的compareTo(ZoneOffset)方法用于比较作为参数传递给这个ZoneOffset实例的另一个ZoneOffset实例。该方法返回一个整数值，即比较器的值。

语法。

public int compareTo(ZoneOffset anotherZoneOffset)

参数。该方法接受一个参数anotherZoneOffset，该参数将与这个ZoneOffset实例进行比较。

返回值。该方法返回一个整数值，如下所示。

• 如果这个实例大于作为参数传递的实例，那么将返回一个正值
• 如果这个实例等于作为参数传递的实例，那么将返回一个零（0）。
• 如果这个实例小于作为参数传递的实例，那么将返回一个负值。

异常情况。如果作为参数传递的另一个ZoneOffset是空的，该方法会抛出NullPointerException。

下面的例子说明了ZoneOffset.compareTo()方法。

例1:

// Java code to illustrate compareTo() method
  
import java.time.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Get the ZoneOffset instance
        ZoneOffset zoneOffset1
            = ZoneOffset.ofHours(5);
        System.out.println("ZoneOffset 1: "
                           + zoneOffset1);
  
        // Get the ZoneOffset instance
        ZoneOffset zoneOffset2
            = ZoneOffset.ofHours(5);
        System.out.println("ZoneOffset 2: "
                           + zoneOffset2);
  
        // Get the ZoneOffset instance
        ZoneOffset zoneOffset3
            = ZoneOffset.ofHours(3);
        System.out.println("ZoneOffset 3: "
                           + zoneOffset3);
  
        // Using compareTo() method
        System.out.println("ZoneOffset 1 "
                           + "compared to ZoneOffset 2: "
                           + zoneOffset1.compareTo(zoneOffset2));
  
        // Using compareTo() method
        System.out.println("ZoneOffset 1 "
                           + "compared to ZoneOffset 3: "
                           + zoneOffset1.compareTo(zoneOffset3));
  
        // Using compareTo() method
        System.out.println("ZoneOffset 3 "
                           + "compared to ZoneOffset 1: "
                           + zoneOffset3.compareTo(zoneOffset1));
    }
}

输出:

ZoneOffset 1: +05:00
ZoneOffset 2: +05:00
ZoneOffset 3: +03:00
ZoneOffset 1 compared to ZoneOffset 2: 0
ZoneOffset 1 compared to ZoneOffset 3: -7200
ZoneOffset 3 compared to ZoneOffset 1: 7200

例2：显示NullPointerException

// Java code to illustrate compareTo() method
  
import java.time.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        try {
            // Get the ZoneOffset instance
            ZoneOffset zoneOffset
                = ZoneOffset.ofHours(3);
            System.out.println("ZoneOffset: "
                               + zoneOffset);
  
            // Using compareTo() method
            System.out.println("ZoneOffset "
                               + "compared to null: ");
  
            zoneOffset.compareTo(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出。

ZoneOffset: +03:00
ZoneOffset compared to null: 
java.lang.NullPointerException