UPDATE: Is there any way to use Java 8 libraries in the Processing IDE?

Features include -

• Intuitive graphical node-based patching, where every component is similar to a Processing sketch - mix multiple sketches together without the overhead.
• Wide range of pre-built components.
• Real-time live programming - rewrite any component as it is running, without missing a frame, for live coding or faster creative development.
• Integrated GStreamer 1.x support with re-codeable playback and capture components.
• Unlimited number of pipelines, running locally or remotely - run in multiple processes for improved performance or crash-free multiple windows; run across multiple machines for large projects or live-coding a Pi.
• Audio library with JACK support, and ability to re-code synthesis down to the per-sample level.
• Integrated GUI, MIDI, TinkerForge, OSC and Syphon/Spout bindings.
• Threading done right - entirely lock-free communication between pipelines, locally and remotely; background resource loading and management.
• Compositing fixed - pre-multiplied alpha ensures correct blending across multiple transparent surfaces.
• Professional IDE base (Apache NetBeans) with full code-completion and support for Java 8 features.
• Fully FLOSS stack, including bundled OpenJDK on Windows and macOS.

Recent changes include -

• PraxisCORE runtime is now LGPL, with support for standalone projects.
• Support for using any Java libraries, and access to underlying Processing PApplet, images and graphics for library integration (eg. HE_Mesh above).
• Data root pipelines and improved reference handling for building custom background tasks, IO, passing around geometry data, etc.
• Most built-in components now re-codeable, including video composite, mixer, player and capture.
• Improved UI, with start page tasks for installing examples and additional components; updated graph UI (with bezier curves!)

Download from - https://www.praxislive.org
Online documentation (still being updated for v4) - http://praxis-live.readthedocs.io

menuBarButtons.add(new TextButton("File", 0, 0, 20, menuBarHeight, (() -> println("Test")) ));

However, processing gives the error

Lambda expressions are allowed only at source level 1.8 or above

This is quite easy to fix in any normal java IDE by changing the JRE in the build path configuration, but I can't find any option for this in the settings. I tried copy pasting a more up to date JRE into the processing folder, but to no avail. Please help me.

Thanks!