Open Source Tips

Monday, June 20, 2022

JavaFX Book Review

Learn JavaFX 17 is a good book with good examples but JavaFX has some unique features that can be issues in your use the platform.

Note that JavaFX 17 requires purchase of a license. There is no free developer version of JavaFX 17. A free developer version of JavaFX 18 is available and that is what I am using and I have not found any code from the book that dows not work in JavaFX 18 but I have only run a few examples so far.

JavaFX 17 lacks free developer versions because the JavaFX project isn't run like a Free Open Source project.

JavaFX was an Oracle project for many years and therefore, closely tied to use of the NetBeans IDE. This is no longer the case and the book Learn JavaFX 17 presents examples using the Eclipse IDE. The best experience I got from an IDE was from the community edition of IntelliJ IDEA. On both Windows and Mac, I had an example JavaFX app within two minutes of installing the IDE.

Monday, January 3, 2022

Algorithmic Thinking Snowflake Problem

The challenge in this problem is to identify identical snowflakes even when the data about the snowflakes are stored in the same sequence but in a different orientation. In this problem, snowflakes have six arms of lengths varying from 1 to 6. The snowflakes are randomly generated so one snowflake may have arms represented by [1, 2, 3, 4, 5, 6] and an identical snowflake have arms of [3, 4, 5, 6, 1, 2]. These are a match. These snowflakes are identical but were generated with different orientations. A snowflake with arms of [2, 1, 3, 4, 5, 6] is not a match because its arms, even though of the same lengths, do not occur in a sequence that can be made to match the first two.

In the function makeSnowflakes() my solution generates 2000 snowflakes as the problem set. Then in searchArrayForMatches() and identifyIdentical() the program compares each arm of each snowflake to the arms of every other snowflake.

I wrote and tested this in Xcode, the Mac IDE.

Caveat: I've coded very little C and it probably shows.

	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <time.h>
	#include <stdbool.h>
	const int SIZEOFFLAKESARRAY = 2000;
	static int flakes[SIZEOFFLAKESARRAY][6];

	void makeSnowflakes() {
	time_t t;
	srand((unsigned) time(&t));
	for (int i = 0; i < SIZEOFFLAKESARRAY; i++) {
	for (int j = 0; j < 6; j++) {
	int num = 1 + rand() % (6);
	flakes[i][j] = num;
	}
	}
	}
	bool identifyIdentical(int a, int b) {
	bool allSixArmsMatch = true;
	for (int secondArmOffset = 0; secondArmOffset < 6; secondArmOffset++) {
	allSixArmsMatch = true;
	for (int armIndex = 0; armIndex < 6; armIndex++) {
	int totalOffset = armIndex + secondArmOffset;
	if (totalOffset > 5) {
	totalOffset -= 6;
	}
	if (flakes[a][armIndex] != flakes[b][totalOffset]) {
	allSixArmsMatch = false;
	break;
	}
	}
	if (allSixArmsMatch) break;
	}
	if (allSixArmsMatch) printf("\nmatch %d %d \n%d %d %d %d %d %d \n%d %d %d %d %d %d", a, b,
	flakes[a][0], flakes[a][1], flakes[a][2], flakes[a][3], flakes[a][4], flakes[a][5],
	flakes[b][0], flakes[b][1], flakes[b][2], flakes[b][3], flakes[b][4], flakes[b][5]);
	return allSixArmsMatch;
	}
	int searchArrayForMatches() {
	bool matched = false;
	int nbrMatched = 0;
	for (int firstSnowflake = 0; firstSnowflake < SIZEOFFLAKESARRAY - 1; firstSnowflake++) {
	for (int secondSnowflake = firstSnowflake + 1; secondSnowflake < SIZEOFFLAKESARRAY; secondSnowflake++) {
	matched = identifyIdentical(firstSnowflake, secondSnowflake);
	if (matched) nbrMatched += 1;
	}
	}
	return nbrMatched;
	}
	int main() {
	makeSnowflakes();

	// create match for test case
	for (int x=0; x<6; x++) {
	int offset = x + 2; if (offset > 5) offset -= 6;
	flakes[SIZEOFFLAKESARRAY - 1][offset] = flakes[SIZEOFFLAKESARRAY - 2][x];
	}

	int nbrMatched = searchArrayForMatches();
	printf("\nNumber Matched %d\n", nbrMatched);
	return 0;
	}

view raw snowflakes.c hosted with ❤ by GitHub

Program Output

. . .
match 1749 1824 
3 2 6 5 5 3 
5 3 3 2 6 5
match 1759 1859 
3 3 6 6 5 1 
3 6 6 5 1 3
match 1776 1900 
4 4 5 2 4 5 
2 4 5 4 4 5
match 1860 1905 
6 5 2 3 4 6 
6 5 2 3 4 6
match 1915 1977 
3 1 1 1 5 4 
1 1 1 5 4 3
match 1998 1999 
1 6 3 2 6 1 
6 1 1 6 3 2
Number Matched 244
Program ended with exit code: 0

Friday, June 18, 2021

Creating and Populating a Database With Apache ANT

I recreated a very useful ANT script I originally created 15 or 16 years ago. The ANT script containing the database creation commands can be versioned making sharing, reuse and modification simple and easy.

Preliminary Setup

1.) install Apache ANT
   a.) download the zip file
   b.) open the zip and copy the contents to the clipboard
   c.) paste the content of the clipboard in a folder
   d.) create an ANT_HOME environment variable and give it the value of the path of the location of the ANT files
   e.) edit the PATH environment variable and add ANT_HOME to it
2.) download the H2 DBMS jar file and place it in the lib folder
3.) write the sql tasks in the ANT build.xml file.

Here is the build.xml file that contains the SQL commands that ANT will run:

	<project name="h2db" basedir="." default="echo">

	<property name="sqldriver.jar" value="lib/h2-1.4.200.jar"/>
	<property name="url" value="jdbc:h2:~/h2db"/>
	<property name="driver" value="org.h2.Driver"/>
	<property name="userid" value="root"/>
	<property name="password" value="root"/>

	<target name="echo">
	<echo>The targets that can be run are: </echo>
	<echo>ant sqlcreate</echo>
	<echo>ant sqlschema</echo>
	<echo>ant sqlpopulate</echo>
	<echo>ant sqlselect</echo>
	<echo>ant sqldrop</echo>
	</target>

	<target name="sqlschema">
	<sql
	driver="${driver}"
	url="${url}"
	userid="${userid}"
	password="${password}"
	print="yes"
	classpath="${sqldriver.jar}">
	SHOW TABLES;
	</sql>
	</target>

	<target name="sqldrop">
	<sql
	driver="${driver}"
	url="${url}"
	userid="${userid}"
	password="${password}"
	print="yes"
	classpath="${sqldriver.jar}">
	drop VIEW if exists ProjProg;
	drop INDEX if exists Programmer_idx;
	drop INDEX if exists Project_idx;
	drop TABLE if exists ProjectProgrammer;
	drop TABLE if exists Programmer;
	drop TABLE if exists Project;
	</sql>
	</target>

	<target name="sqlcreate">
	<sql
	driver="${driver}"
	url="${url}"
	userid="${userid}"
	password="${password}"
	print="yes"
	classpath="${sqldriver.jar}">
	create table Project (ID INT AUTO_INCREMENT, name varchar(30));
	create index Project_idx on Project (name);
	create table Programmer (ID INT AUTO_INCREMENT, full_name varchar(100));
	create index Programmer_idx on Programmer (full_name);
	create table ProjectProgrammer (project_id INTEGER, programmer_id INTEGER);
	create view ProjProg as select Project.name, Programmer.full_name
	from Programmer
	join ProjectProgrammer
	on Programmer.id = ProjectProgrammer.programmer_id
	join Project
	on ProjectProgrammer.project_id = Project.id;
	</sql>
	</target>

	<target name="sqlpopulate" >
	<sql
	driver="${driver}"
	url="${url}"
	userid="${userid}"
	password="${password}"
	print="yes"
	classpath="${sqldriver.jar}">
	insert into Programmer (full_name) values('Greg Helton');
	insert into Programmer (full_name) values('Bill Gates');
	insert into Programmer (full_name) values('Steve Jobs');
	insert into Project (name) values('Workplace assignments');
	insert into ProjectProgrammer values(1,1);
	insert into ProjectProgrammer values(1,2);
	insert into ProjectProgrammer values(1,3);
	</sql>
	</target>

	<target name="sqlselect" >
	<sql
	driver="${driver}"
	url="${url}"
	userid="${userid}"
	password="${password}"
	print="yes"
	classpath="${sqldriver.jar}">
	select * from Project;

	select * from Programmer;

	select *
	from Programmer
	join ProjectProgrammer
	on Programmer.id = ProjectProgrammer.programmer_id
	join Project
	on ProjectProgrammer.project_id = Project.id;

	select * from ProjProg;
	</sql>
	</target>
	</project>

view raw build.xml hosted with ❤ by GitHub

C:\Users\javap\dev\src\java\h2Db>ant -v sqlcreate
Apache Ant(TM) version 1.10.10 compiled on April 12 2021
Trying the default build file: build.xml
Buildfile: C:\Users\javap\dev\src\java\h2Db\build.xml
Detected Java version: 11 in: C:\Program Files\Java\jdk-11.0.1
Detected OS: Windows 10
parsing buildfile C:\Users\javap\dev\src\java\h2Db\build.xml with URI = file:/C:/Users/javap/dev/src/java/h2Db/build.xml
Project base dir set to: C:\Users\javap\dev\src\java\h2Db
parsing buildfile jar:file:/C:/Users/javap/dev/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml with URI = 
jar:file:/C:/Users/javap/dev
/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
Build sequence for target(s) `sqlcreate' is [sqlcreate]
Complete build sequence is [sqlcreate, sqlpopulate, echo, sqlschema, sqldrop, sqlselect, ]

sqlcreate:
      [sql] connecting to jdbc:h2:~/h2db
      [sql] Loading org.h2.Driver using AntClassLoader with classpath C:\users\javap\dev\lib\h2-1.4.200.jar
      [sql] Executing commands
      [sql] SQL:  create table Project (ID INT AUTO_INCREMENT, name varchar(30))
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:  create index Project_idx on Project (name)
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:  create table Programmer (ID INT AUTO_INCREMENT, full_name varchar(100))
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:  create index Programmer_idx on Programmer (full_name)
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:  create table ProjectProgrammer (project_id INTEGER, programmer_id INTEGER)
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:  create view ProjProg as select Project.name, Programmer.full_name from Programmer 
      join ProjectProgrammer on Programmer.id = ProjectProgrammer.programmer_id 
      join Project on ProjectProgrammer.project_id = Project.id
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] Committing transaction
      [sql] 6 of 6 SQL statements executed successfully

BUILD SUCCESSFUL
Total time: 0 seconds

C:\Users\javap\dev\src\java\h2Db>ant -v sqlpopulate
Apache Ant(TM) version 1.10.10 compiled on April 12 2021
Trying the default build file: build.xml
Buildfile: C:\Users\javap\dev\src\java\h2Db\build.xml
Detected Java version: 11 in: C:\Program Files\Java\jdk-11.0.1
Detected OS: Windows 10
parsing buildfile C:\Users\javap\dev\src\java\h2Db\build.xml with URI = file:/C:/Users/javap/dev/src/java/h2Db/build.xml
Project base dir set to: C:\Users\javap\dev\src\java\h2Db
parsing buildfile jar:file:/C:/Users/javap/dev/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml with 
URI = jar:file:/C:/Users/javap/dev
/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
Build sequence for target(s) `sqlpopulate' is [sqlpopulate]
Complete build sequence is [sqlpopulate, sqlcreate, echo, sqlschema, sqldrop, sqlselect, ]

sqlpopulate:
      [sql] connecting to jdbc:h2:~/h2db
      [sql] Loading org.h2.Driver using AntClassLoader with classpath C:\users\javap\dev\lib\h2-1.4.200.jar
      [sql] Executing commands
      [sql] SQL:  insert into Programmer (full_name) values('Greg Helton')
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into Programmer (full_name) values('Bill Gates')
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into Programmer (full_name) values('Steve Jobs')
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into Project (name) values('Workplace assignments')
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into ProjectProgrammer values(1,1)
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into ProjectProgrammer values(1,2)
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] SQL:  insert into ProjectProgrammer values(1,3)
      [sql] 1 rows affected
      [sql] 1 rows affected
      [sql] Committing transaction
      [sql] 7 of 7 SQL statements executed successfully

BUILD SUCCESSFUL
Total time: 0 seconds

C:\Users\javap\dev\src\java\h2Db>ant -v sqlselect
Apache Ant(TM) version 1.10.10 compiled on April 12 2021
Trying the default build file: build.xml
Buildfile: C:\Users\javap\dev\src\java\h2Db\build.xml
Detected Java version: 11 in: C:\Program Files\Java\jdk-11.0.1
Detected OS: Windows 10
parsing buildfile C:\Users\javap\dev\src\java\h2Db\build.xml with URI = file:/C:/Users/javap/dev/src/java/h2Db/build.xml
Project base dir set to: C:\Users\javap\dev\src\java\h2Db
parsing buildfile jar:file:/C:/Users/javap/dev/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml with 
URI = jar:file:/C:/Users/javap/dev
/bin/apache-ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
Build sequence for target(s) `sqlselect' is [sqlselect]
Complete build sequence is [sqlselect, sqlpopulate, sqlcreate, echo, sqlschema, sqldrop, ]

sqlselect:
      [sql] connecting to jdbc:h2:~/h2db
      [sql] Loading org.h2.Driver using AntClassLoader with classpath C:\users\javap\dev\lib\h2-1.4.200.jar
      [sql] Executing commands
      [sql] SQL:  select * from Project
      [sql] Processing new result set.
      [sql] ID,NAME
      [sql] 1,Workplace assignments
      [sql]
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:   select * from Programmer
      [sql] Processing new result set.
      [sql] ID,FULL_NAME
      [sql] 1,Greg Helton
      [sql] 2,Bill Gates
      [sql] 3,Steve Jobs
      [sql]
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:   select * from Programmer join ProjectProgrammer on Programmer.id = ProjectProgrammer.programmer_id 
      join Project on ProjectProgrammer.project_id = Project.id
      [sql] Processing new result set.
      [sql] ID,FULL_NAME,PROJECT_ID,PROGRAMMER_ID,ID,NAME
      [sql] 1,Greg Helton,1,1,1,Workplace assignments
      [sql] 2,Bill Gates,1,2,1,Workplace assignments
      [sql] 3,Steve Jobs,1,3,1,Workplace assignments
      [sql]
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] SQL:   select * from ProjProg
      [sql] Processing new result set.
      [sql] NAME,FULL_NAME
      [sql] Workplace assignments,Greg Helton
      [sql] Workplace assignments,Bill Gates
      [sql] Workplace assignments,Steve Jobs
      [sql]
      [sql] 0 rows affected
      [sql] 0 rows affected
      [sql] Committing transaction
      [sql] 4 of 4 SQL statements executed successfully

BUILD SUCCESSFUL
Total time: 0 seconds

C:\Users\javap\dev\src\java\h2Db>

Wednesday, November 25, 2020

Is It Digits?

Does a String value consist only of digits?

if (mystr.chars().allMatch(Character::isDigit)) {
  System.out.println("all digits");
}

Tuesday, August 25, 2020

Iterative Test Driven Development circa 1968

A crisis in software engineering came about in the late 1960s from the marketing of a computer that was much cheaper to own and operate, the IBM 360 family of computers. Fred Brooks managed the development of OS/360 and Gene Amdahl was the architect. These computers allowed software to run on a range of computers which meant that the cost of development could be absorbed across many systems and many years. The software industry saw the opportunity to develop new systems but there was an insufficent number of experienced developers available to develop the software. Larger projects also required more intensive levels of management.

The 1968 NATO Software Engineering Conference was held three years after delivery of IBM's OS/360 that initiated recognition of a crisis in the realms of planning, scheduling and completing software. Brooks best illustrates the problem of scheduling by identifying "the mythical man-month" and illustrating it with a quote from another computer scientist: "while it takes one woman nine months to make one baby, nine women can't make a baby in one month".

At the 1968-69 NATO Software Engineering Conference an oddly familiar methodology was discussed:

SDLC and the waterfall methodolgy appear to be the worst possible way of addressing the the problem of scheduling a project and completing it successfully but, SDLC was adopted because it was the most easily communicated. The 'engineering' part of 'software engineering' became conflated with SDLC.

Friday, August 14, 2020

JUnit & DOS

When I tried coding this in VS Code, the plug-in did not recognize the system JDK so I reverted to DOS just because.

	javac -d bin src/boss/ScoreCollection.java

	javac -cp lib\junit-4.13.jar -d bin test/boss/ScoreCollectionTest.java

	javac -cp lib\junit-4.13.jar;bin -d bin test/boss/TestRunner.java

	java -cp bin;lib/junit-4.13.jar;lib/hamcrest-core-1.3.jar boss.TestRunner

	Result:
	test(boss.ScoreCollectionTest): Not yet implemented
	false

	For version 2:

	javac -cp bin;lib\junit-4.13.jar;lib\hamcrest-core-1.3.jar -d bin test/boss/ScoreCollectionTest.java

	java -cp bin;lib/junit-4.13.jar;lib/hamcrest-core-1.3.jar boss.TestRunner

view raw Commands hosted with ❤ by GitHub

	package boss;

	@FunctionalInterface
	public interface Scoreable {
	int getScore();
	}

view raw Scoreable.java hosted with ❤ by GitHub

	package boss;
	import java.util.*;

	public class ScoreCollection {
	private List<Scoreable> scores = new ArrayList<>();
	public void add(Scoreable scoreable) {
	scores.add(scoreable);
	}
	public int arithmeticMean() {
	int total = scores.stream().mapToInt(Scoreable::getScore).sum();
	return total / scores.size();
	}
	}

view raw ScoreCollection.java hosted with ❤ by GitHub

	package boss;
	import static org.junit.Assert.*;
	import org.junit.*;

	public class ScoreCollectionTest {
	@Test
	public void test() {
	fail("Not yet implemented");
	}
	}

view raw ScoreCollectionTest.java hosted with ❤ by GitHub

	package boss;
	import static org.junit.Assert.*;
	import static org.hamcrest.core.IsEqual.equalTo;
	import static org.hamcrest.MatcherAssert.assertThat;
	import org.junit.*;

	public class ScoreCollectionTest {
	@Test
	public void answersArithmeticMeanOfTwoNumbers() {
	ScoreCollection coll = new ScoreCollection();
	coll.add(() -> 5);
	coll.add(() -> 7);
	int actualResult = coll.arithmeticMean();
	assertThat(actualResult, equalTo(6));
	}
	}

view raw ScoreCollectionTest.java Version 2 hosted with ❤ by GitHub

	package boss;
	import org.junit.runner.JUnitCore;
	import org.junit.runner.Result;
	import org.junit.runner.notification.Failure;

	public class TestRunner {
	public static void main(String[] args) {
	Result result = JUnitCore.runClasses(ScoreCollectionTest.class);

	for (Failure failure : result.getFailures()) {
	System.out.println(failure.toString());
	}

	System.out.println(result.wasSuccessful());
	}
	}

view raw TestRunner.java hosted with ❤ by GitHub

Saturday, October 5, 2019

Webassembly Example C and C++ to HTML

Compiling C and C++ directly into a running web app is a thrill.

C Example

Save the following code to hello.c.

#include <stdio.h>
int main(int arg, char ** argv) {
  printf("Hello, world\n");
}

Note: point to the sdk! Run once after opening a terminal session, modifying the path to match your implementation.

$ source ~/dev/bin/emsdk/emsdk_env.sh --build=Release

Then, compile and run:

$ emcc hello.c -o hello.html
$ python -m SimpleHTTPServer 9000

open browser to http://localhost:9000/hello.html

C++ Example

Save the following code to dbldata.cpp.

#include <iostream>
struct Double_Data {
  Double_Data(const size_t size) : data(new double[size]) {}
  ~Double_Data() { delete [] data; }
  double *data;
};

Double_Data get_data() {
  Double_Data data(3);
  data.data[0] = 1.1; data.data[1] = 2.2; data.data[2] = 3.3;
  return data;
}

double sum_data(const Double_Data &d) {
  return d.data[0] + d.data[1] + d.data[2];
}

int main() {
  std::cout << sum_data(get_data()) << std::endl;
}

Note: point to the sdk! Run once after opening a terminal session, modifying the path to match your implementation.

$ source ~/dev/bin/emsdk/emsdk_env.sh --build=Release

Then, compile and run:

$ em++ dbldata.cpp -s -o dbldata.html
$ python -m SimpleHTTPServer 9000

open browser to http://localhost:9000/dbldata.html

C++ and Templates Example

Save the following code to dbldata.cpp.

#include <iostream>
template<typename Value_Type>
struct Data {
  Data(const size_t size) : data(new Value_Type[size]) {}
  ~Data() { delete [] data; }
  Value_Type *data;
};

template<typename Value_Type>
Data<Value_Type> get_data(const Value_Type &v1, 
                          const Value_Type &v2, 
                          const Value_Type &v3) {
  Data<Value_Type> d(3);
  d.data[0] = v1; d.data[1] = v2; d.data[2] = v3;
  return d;
}

template<typename Value_Type>
Value_Type sum_data(const Data<Value_Type> &d) {
  return d.data[0] + d.data[1] + d.data[2];
}

int main() {
  std::cout << sum_data(get_data(1.1, 3.3, 5.5)) << std::endl;
  std::cout << sum_data(get_data(11, 22, 33)) << std::endl;
}

Compile and run as before.

Running Example From bash Terminal

Verify the code is valid C++ by compiling and executing from the command line:

$ g++ dbldata.cpp -o dbldata
$ ./dbldata
9.9
66

The code in the C++ example was taken from Jason Turner's CppCon presentation "The Best Parts of C++"