Java TemporalAccessor

last modified March 6, 2025

In this article, we explore the TemporalAccessor interface in Java. We'll access temporal fields, check supported fields, and use it with LocalTime as an example implementation.

TemporalAccessor is a foundational interface in the ISO-8601 calendar system's java.time package. It provides read-only access to temporal objects like time or date.

TemporalAccessor is implemented by classes such as LocalTime and LocalDate. It's immutable and focuses on querying temporal fields without modification.

Accessing Temporal Fields

Use TemporalAccessor to query fields like hour or minute via ChronoField.

import java.time.LocalTime;
import java.time.temporal.ChronoField;

void main() {
    LocalTime time = LocalTime.now();
    int hour = time.get(ChronoField.HOUR_OF_DAY);
    System.out.println("Hour: " + hour);
}

This retrieves the current hour.

The code creates a LocalTime object with the current time using LocalTime.now. It then uses get with ChronoField.HOUR_OF_DAY to extract and print the hour.

Checking Supported Fields

isSupported verifies if a field is available in a TemporalAccessor.

import java.time.LocalTime;
import java.time.temporal.ChronoField;

void main() {
    LocalTime time = LocalTime.of(15, 30);
    if (time.isSupported(ChronoField.MINUTE_OF_HOUR)) {
        int minute = time.get(ChronoField.MINUTE_OF_HOUR);
        System.out.println("Minute: " + minute);
    }
}

This checks and retrieves the minute.

Here, LocalTime.of(15, 30) sets a specific time. The isSupported method checks if MINUTE_OF_HOUR is valid before get retrieves and prints the minute.

if (time.isSupported(ChronoField.MINUTE_OF_HOUR)) {

isSupported ensures the field exists before access.

TemporalAccessor with LocalTime

LocalTime implements TemporalAccessor. Compare their usage:

import java.time.LocalTime;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.ChronoField;

void main() {
    TemporalAccessor time = LocalTime.of(7, 20);
    int hour = time.get(ChronoField.HOUR_OF_DAY);
    System.out.println("Hour: " + hour);
}

This uses TemporalAccessor generically.

This example declares time as a TemporalAccessor, showing its interface usage. LocalTime.of(7, 20) sets the time, and get extracts the hour using ChronoField.

Common Temporal Fields

LocalTime as a TemporalAccessor supports fields like:

• HOUR_OF_DAY: 0-23
• MINUTE_OF_HOUR: 0-59
• SECOND_OF_MINUTE: 0-59

import java.time.LocalTime;
import java.time.temporal.ChronoField;

void main() {
    LocalTime time = LocalTime.now();
    System.out.printf("Hour: %d%n", time.get(ChronoField.HOUR_OF_DAY));
    System.out.printf("Minute: %d%n", time.get(ChronoField.MINUTE_OF_HOUR));
    System.out.printf("Second: %d%n", time.get(ChronoField.SECOND_OF_MINUTE));
}

This splits time into components.

The code uses LocalTime.now to get the current time. It then extracts hour, minute, and second using ChronoField constants and prints them with formatted output via printf.

Limitations

TemporalAccessor is read-only. For adjustments, use Temporal:

import java.time.LocalTime;

void main() {
    LocalTime time = LocalTime.now();
    LocalTime later = time.plusHours(3); // Requires Temporal
    System.out.println("Now: " + time);
    System.out.println("Later: " + later);
}

This demonstrates a limitation of TemporalAccessor. While it can query fields, modification like adding hours via plusHours requires the Temporal interface, which LocalTime also implements.

Source

Java TemporalAccessor - language reference

In this article, we have explored Java TemporalAccessor.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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