I saw same issue
http://esotericsoftware.com/forum/Spine-Viewer-crashes-from-No-Such-Method-12911?p=57297&hilit=viewer#p57297
com.badlogic.gdx.utils.GdxRuntimeException: java.lang.NoSuchMethodError: java.nio.FloatBuffer.flip()Ljava/nio/FloatBuffer;
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:135)
Caused by: java.lang.NoSuchMethodError: java.nio.FloatBuffer.flip()Ljava/nio/FloatBuffer;
at com.badlogic.gdx.graphics.glutils.VertexArray.<init>(VertexArray.java:59)
at com.badlogic.gdx.graphics.Mesh.<init>(Mesh.java:187)
at com.badlogic.gdx.graphics.Mesh.<init>(Mesh.java:158)
at com.badlogic.gdx.graphics.g2d.SpriteBatch.<init>(SpriteBatch.java:103)
at com.badlogic.gdx.graphics.g2d.SpriteBatch.<init>(SpriteBatch.java:80)
at com.badlogic.gdx.scenes.scene2d.Stage.<init>(Stage.java:100)
at com.esotericsoftware.spine.SkeletonViewer$UI.<init>(SkeletonViewer.java:423)
at com.esotericsoftware.spine.SkeletonViewer.create(SkeletonViewer.java:124)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:151)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:128)
and this is my java version
java version "1.8.0_231"
Java(TM) SE Runtime Environment (build 1.8.0_231-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.231-b11, mixed mode)
