For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh/openSUSE_Tumbleweed/home:brassh.repo
zypper refresh
zypper install java-1_8_0-openjdk
For graphics run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh/graphics/home:brassh.repo
zypper refresh
zypper install java-1_8_0-openjdk
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh/15.6/home:brassh.repo
zypper refresh
zypper install java-1_8_0-openjdk