I just installed opensuse 13.1 OS on my laptop but lost on which directory to install the java development kit. Please if somebody can provide me with the solution. Thanks.
You don’t install it to any directory, you just install java-1_7_0-openjdk-devel either via YAST or zypper.
zypper in java-1_7_0-openjdk-devel
If you have some absolute need to use the Oracle’s Java, you can acquire the .RPM from their website, install it using zypper again ( but just point it to the rpm, zypper in /home/user/java.rpm )