why I can't install netbeans on linux(centos)? [closed]

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http://stackoverflow.com – I downloaded the netbeans. I followed the Installation Instructions ,but the terminal display the following things: Configuring the installer... Searching for JVM on the system... Extracting installation data... Installer file /home/jiangkai/netbeans-7.2.1-ml-linux.sh seems to be corrupted What's the problems did I confronted with? I use CentOS(6.3) and installed jdk7u11. (HowTos)