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Resolve 'error: package android.support.v7.app does not exist' and 'cannot resolve symbol AppCompatActivity' by migrating to AndroidX in Gradle.
Master Java UDP socket programming: complete client-server code using DatagramSocket and DatagramPacket, packet buffering, and MTU mechanics.
Automate RSS 2.0 XML feed generation from website URLs using Bash, curl, date RFC-822 formatting, and XML entity escaping.
Understand Linux terminal file color codes: reference color tables for directories, symlinks, SUID, and customize LS_COLORS using dircolors.
Master essential open-source Linux performance and debugging tools: strace, ltrace, perf, Valgrind, iostat, ss, and iperf3 with command workflows.
View and edit raw binary ELF files using hexedit terminal utility: inspect byte offsets, edit ASCII strings, and patch executable byte patterns.
Delete the first N characters of every line in Vim / Vi editor: use visual block mode (Ctrl + v), execute :%s/^...//, or use sed 's/^.\{3\}//'.
Fix media player video playback freezes on Ubuntu Linux: configure VA-API / NVDEC hardware acceleration, switch Xorg vs Wayland, and update Mesa.
Master the Linux top command: monitor real-time CPU usage, memory utilization (VIRT, RES, SHR), process states, load averages, and sort by PID.
