Lesson 6.8 · Write it

Pick the warnings out of a log

A whole programPython or Java8 tests, 6 of them hidden

On a phone? Put the lines in order instead

A program writes a log file, log.txt, with one message per line. Write a program that prints only the warnings, then how many there were.

A warning is a line whose first four characters are WARN, in capital letters, whatever follows them: WARN disk full, WARNING low and WARN:fan are all warnings. A line that has WARN somewhere later, or starts with warn or Warn, is not a warning.
Print each warning exactly as it is in the file, in the order they appear.
After the last line of the file, print Warnings: followed by the number of warnings. If there are none, that is Warnings: 0.
The file may be empty. A line may be empty or shorter than four characters. The last line may or may not end with a line end. No line starts with a space.

Your program is run several times, each time in a folder that holds only the files shown for that run. Spaces at the end of a printed line are ignored.

Running Java here comes later. You can put this answer's lines in order instead. You can still write your Java answer (it stays while this page is open) and compare it with our worked solution. Or try this exercise in Python.

Examples

Your program is run 8 times: the 2 examples below, and 6 hidden ones that check the rules above. Only what it prints is checked. Each run starts in an empty folder that holds only the files shown for it.

two of the four lines start with WARN (rules 1 to 3)

You type

Nothing

It prints

WARN disk 91% full
WARN battery low
Warnings: 2

Files in its folder

log.txt

INFO started
WARN disk 91% full
INFO saved 3 files
WARN battery low

one warning, on the last line (rules 2 and 3)
You type
Nothing
It prints
```
WARN low ink
Warnings: 1
```
Files in its folder
log.txt
```
INFO all fine
WARN low ink
```

solution.pySolution.java

# Print what the question asks for.

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