ISO 8601 Time Duration Parsing in Java 7

Question

I am parsing the YouTube API v3 and trying to extract the duration which seems to be in ISO 8601 format. Now, there are inbuilt methods in Java 8, but that requires that I would have to bump the API level to 26 (Android O), which I cannot do. Any way to parse it natively? Example string I am using is: PT3H12M

Answer 1

Good news! Now you can desugar the java.time API with the Android Gradle plugin 4.0.0+

https://developer.android.com/studio/write/java8-support#library-desugaring

So this will allow you using inbuilt methods from Java 8 related to java.time api :)

Here you have detailed specification of desugared api:

https://developer.android.com/studio/write/java8-support-table

And what you only need to do is to bump the version of Android plugin to 4.0.0+ and add those lines to your app-module level build.gradle:

android {
  defaultConfig {
    // Required when setting minSdkVersion to 20 or lower
    multiDexEnabled true
  }

  compileOptions {
    // Flag to enable support for the new language APIs
    coreLibraryDesugaringEnabled true
    // Sets Java compatibility to Java 8
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

dependencies {
  coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.0.9'
}

Answer 2

If your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

The following section talks about how you can do it using the modern date-time API.

With Java-8:

import java.time.Duration;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        Duration duration = Duration.parse("PT3H12M");
        LocalTime time = LocalTime.of((int) duration.toHours(), (int) (duration.toMinutes() % 60));
        System.out.println(time.format(DateTimeFormatter.ofPattern("h:m a")));
    }
}

Output:

3:12 am

With Java-9:

import java.time.Duration;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        Duration duration = Duration.parse("PT3H12M");
        LocalTime time = LocalTime.of(duration.toHoursPart(), duration.toMinutesPart());
        System.out.println(time.format(DateTimeFormatter.ofPattern("h:m a")));
    }
}

Output:

3:12 am

Note that Duration#toHoursPart and Duration#toMinutesPart were introduced with Java-9.