Error running exec (). Command: [chmod 777] working directory:/data environment:

to execute shell commands in Java Code , you can run the LS command, but the command chmod 777 cannot be executed successfully. The console displays the following information: (this is part of the information)

JAVA. io. ioexception: Error running exec (). command: [chmod 777] working directory:/data environment: [android_socket_zygote = 10, android_bootlogo = 1, external_storage =/storage/sdcard0, android_assets =/system/app, path =/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin,
asec_mountpoint =/mnt/ASEC, loop_mountpoint =/mnt/OBB, bootclasspath =/system/framework/core. jar:/system/framework/core-junit.jar:/system/framework/bouncycastle. jar:/system/framework/Ext. jar:/system/framework/hwframework. jar:/system/framework. jar:/system/framework/framework_ext.jar:/system/framework/android. policy. jar:/system/framework/services. jar:/system/framework/apache-xml.jar:/system/framework/filterfw. jar:/system/framework/qcnvitems. jar:/system/framework/qcrilhook. jar,
android_data =/data, LD_LIBRARY_PATH =/vendor/lib:/data/Cust/lib:/system/lib:/data/datalib, android_root =/system, android_property_workspace = 9,65536]

Caused by: Java. Io. ioexception: Permission denied

 
Solution, help?