Develop Reference

Sorting multi-type string ArrayList in Java based on Integers

I have a data Set like this:
1,JOHN,1934
2,TERENCE,1914
3,JOHN,1964
4,JOHN,1904
5,JOHN,1924
6,JOHN,1954
7,JOHN,1944
8,JOHN,1984
9,JOHN,1974
10,JOHN,1994
Which I've loaded in ArrayList of String[] from Text file like this:
ArrayList<String[]> records = new ArrayList<>();
String fileLocation = System.getProperty("user.dir");
String dataPath = fileLocation + File.separator + "boys-names.txt";
try {
try (BufferedReader br = new BufferedReader(new FileReader(dataPath))) {
String line;
while ((line = br.readLine()) != null) {
String[] values = line.split(",");
records.add(values);
}
}
} catch (IOException e) {
e.printStackTrace();
}
I wanted to sort data set in increasing year like this:
4,JOHN,1904
2,TERENCE,1914
5,JOHN,1924
1,JOHN,1934
7,JOHN,1944
6,JOHN,1954
3,JOHN,1964
9,JOHN,1974
8,JOHN,1984
10,JOHN,1994
Problem: The built-in sorting method Collections.sort(list); of ArrayList only works on single type of data. But, in my case I have string with multi-type (string-integer) and sorting should base in Integers. So, is there any way to solve this problem?

Consider defining a model class for your data - let's call it MyData :
public class MyData {
private long id;
private String name;
private Year year;
//getters setters constructor
}
If the last integer value represents a year, why not use java.time.Year directly?
And then you could sort this list using List::sort method and passing a comparator :
Comparator<MyData> comparator = Comparator.comparing(MyData::getYear);
myDataList.sort(comparator);

By using java-8 lambda expression, write custom Comparator that compares Integer values and use Integer.valueOf for converting String to Integer
List<String[]> list = new ArrayList<String[]>();
String[] ar1 = {"1","JOHN","1934"};
String[] ar2 = {"2","TERENCE","1914"};
list.add(ar1);
list.add(ar2);
list.sort((c1,c2)->Integer.valueOf(c1[2]).compareTo(Integer.valueOf(c2[2])));
list.forEach(i->System.out.println(Arrays.toString(i)));
Output
[2, TERENCE, 1914]
[1, JOHN, 1934]

This would work:
public static void main(String[] args) {
List<String[]> records = new ArrayList<>();
records.add(new String[] {"1", "John", "1934"});
records.add(new String[] {"2", "Terence", "1914"});
Collections.sort(
records,
(o1, o2) -> {
Integer year_o1 = Integer.parseInt(o1[2]);
Integer year_o2 = Integer.parseInt(o2[2]);
if (year_o1 < year_o2) {
return -1;
} else if (year_o1 > year_o2) {
return 1;
} else {
return 0;
}
});
}

Map array to object

I have an array defined as follows:
String [] source = {"26", "Tom", "foo", ...};
And a Person class:
public class Person{
private String age;
private String name;
private String print;
private String ......;//the same type and order and number of source
public Person() {
}
//full construtors
public Person(String age, String name, String print,String ....) {
this.age = age;
this.name = name;
this.print = print;
//....
}
/* setters & getters */
}
How can I map these values to a Personinstance?
this is my real coding
public static List<BasicalVo> readObject(String path) throws IOException, NoSuchMethodException {
InputStreamReader fReader = new InputStreamReader(new FileInputStream(path),"gb2312");
BufferedReader bufferedReader = new BufferedReader(fReader);
String currentLine;
String[] temp;
List<BasicalVo> basicalVoList= new ArrayList<BasicalVo>();
while ((currentLine = bufferedReader.readLine()) != null) {
temp = currentLine.split(",");//I get the Array
for (int i = 0; i < temp.length; i++) {
//I don't know hot to translate to BasicalVo .
BasicalVo vo = new BasicalVo();
basicalVoList.add(vo);
}
}
return basicalVoList;
}

If the source just contains one person's data then you can do this:
Person p = new Person(source[0], source[1], source[2] ...);
If the array is too short an ArrayIndexOutOfBoundsException will be thrown.

I.
If the array contains only one Person you only need to create the instance like this :
String[] source = new String[]{"26", "tom", "xx", "....."};
Person p = new Person(source[0], source[1], source[2], source[3],...);
Because you'll know how many parameters there is in the constructor and so you won't have an ArrayIndexOutOfBoundsException if the array is well-build
II.
Assuming you have only 3 attributes, you'll be able to do like this if the array is like this :
String[] source = new String[]{"26", "tom", "xx", "22", "john", "yy"};
ArrayList<Person> list = new ArrayList<>()
for (int i = 0; i < source.length; i += 3) {
list.add(new Person(source[i], source[i + 1], source[i + 2]));
}
III.
If you have multiple fields, you would better do like this :
public Person(String[]source) {
this.age = source[0];
this.name = source[1];
this.print = source[2];
//....
}
Because it wouldn't not surcharge the code you have in your loop which read from the data, and make it easier to do your stuff, and in fact this is not hard, because in every case if you have like 20 fields, you'll have to assignate these 20 attributs
IV.
Or last proposition with a factory method :
public static Person createPersoneFromArray(String[] array) {
Person p = new Person();
p.setAge(array[0]);
p.setName(array[1]);
//...
return p;
}
And in the main method :
Person p = Person.createPersoneFromArray(source);

you can also add another constructor to your BasicalVo class which takes a String[] as input :
public BasicalVo(String [] input) {
this.age = input[0];
this.name = input[1];
this.print = input[2];
//....
}
which you then can call in your main as follows without additional for loop
....
temp = currentLine.split(",");
BasicalVo vo = new BasicalVo(temp);
basicalVoList.add(vo);
....

You can use OpenCSV
CSVReader csvReader = new CSVReader(new FileReader("people.csv"),',');
ColumnPositionMappingStrategy mappingStrategy = new ColumnPositionMappingStrategy();
mappingStrategy.setType(Person.class);
String[] columns = new String[]{"age","name","print"};
mappingStrategy.setColumnMapping(columns);
CsvToBean ctb = new CsvToBean();
List personList = ctb.parse(mappingStrategy, csvReader);

In this specific case I think that your best option is to use reflection. Reflection are a set of classes and interfaces that allow you to call different methods at execution time. For instance:
String [] source = { "26", "tom", "xx", ... };
Constructor constructor = Person.class.getConstructors()[0]
constructor.newInstance(source)
Take into account that this example only works because you have only one constructor, and so Person.class.getConstructors()[0] returns the constructor you want. YOu can try to get the specific constructor with Person.class.getConstructors(Class<?>...), in that case you would need to pass as a parameter an array with the type of the arguments.

How to retrieve word after specific word in Java?

I've this kind of String:
{aa=bbbb, cc=blabla1, ee=ffff, cc=blabla2, gg=hhhh, cc=blabla3,.......}
and i want to get a list of all words after cc=.
How can i do it? I'm not very confident with regex stuff.

public static void main(String[] args) {
String input = "aa=bbbb, cc=blabla1, ee=ffff, cc=blabla2, gg=hhhh, cc=blabla3";
String[] splitValues = input.split(", ");
Map<String,List<String>> results = new Hashtable<>();
List<String> valueList = null;
// iterate through each key=value adding to the results
for (String a : splitValues) {
// a = "aa=bbbb" etc
String[] keyValues = a.split("=");
// you can check if values exist. This assumes they do.
String key = keyValues[0];
String value = keyValues[1];
// if it is already in map, add to its value list
if (results.containsKey(key)) {
valueList = results.get(key);
valueList.add(value);
} else {
valueList = new ArrayList<>();
valueList.add(value);
results.put(key, valueList);
}
}
System.out.println("cc= values");
valueList = results.get("cc");
// assumes value is in results
for (String a : valueList)
System.out.println(a);
}

Your question is very vague but I am guessing the String is provided as is, like:
String toSearch = "{aa=bbbb, cc=blabla1, ee=ffff, cc=blabla2, gg=hhhh, cc=blabla3,.......}";
By list I am guessing you are referring to the abstract List object and not to an array. Here is a solution:
String toSearch = "{aa=bbbb, cc=blabla1, ee=ffff, cc=blabla2, gg=hhhh, cc=blabla3,.......}";
List<String> result = new ArrayList<String>();
int prevMatch = 0;
while (toSearch.indexOf("cc=", prevMatch+1) != -1) {
result.add(toSearch.substring( // Substring method.
toSearch.indexOf("cc=",prevMatch+1)+3,toSearch.indexOf(",") //Getting correct indexes.
));
prevMatch = toSearch.indexOf("cc=",prevMatch+1);
}
The prevMatch variable ensures that the indexOf("cc=") that will be returned will be the next one occurring in the String. For the above String the returning ArrayList will contain the words "blabla1","blabla2", "blabla3" and whatever else is encountered.

manipulate and sort text file

I am working on a project where I have been given a text file and I have to add up the points for each team and printout the top 5 teams.
The text file looks like this:
FRAMae Berenice MEITE 455.455<br>
CHNKexin ZHANG 454.584<br>
UKRNatalia POPOVA 453.443<br>
GERNathalie WEINZIERL 452.162<br>
RUSEvgeny PLYUSHCHENKO 191.399<br>
CANPatrick CHAN 189.718<br>
CHNHan YAN 185.527<br>
CHNCheng & Hao 271.018<br>
ITAStefania & Ondrej 270.317<br>
USAMarissa & Simon 264.256<br>
GERMaylin & Daniel 260.825<br>
FRAFlorent AMODIO 179.936<br>
GERPeter LIEBERS 179.615<br>
JPNYuzuru HANYU 197.9810<br>
USAJeremy ABBOTT 165.654<br>
UKRYakov GODOROZHA 160.513<br>
GBRMatthew PARR 157.402<br>
ITAPaul Bonifacio PARKINSON 153.941<br>
RUSTatiana & Maxim 283.7910<br>
CANMeagan & Eric 273.109<br>
FRAVanessa & Morgan 257.454<br>
JPNNarumi & Ryuichi 246.563<br>
JPNCathy & Chris 352.003<br>
UKRSiobhan & Dmitri 349.192<br>
CHNXintong &Xun 347.881<br>
RUSYulia LIPNITSKAYA 472.9010<br>
ITACarolina KOSTNER 470.849<br>
JPNMao ASADA 464.078<br>
UKRJulia & Yuri 246.342<br>
GBRStacey & David 244.701<br>
USAMeryl &Charlie 375.9810<br>
CANTessa & Scott 372.989<br>
RUSEkaterina & Dmitri 370.278<br>
FRANathalie & Fabian 369.157<br>
ITAAnna & Luca 364.926<br>
GERNelli & Alexander 358.045<br>
GBRPenny & Nicholas 352.934<br>
USAAshley WAGNER 463.107<br>
CANKaetlyn OSMOND 462.546<br>
GBRJenna MCCORKELL 450.091<br>
The first three letters represent the team.
the rest of the text is the the competitors name.
The last digit is the score the competitor recived.
Code so far:
import java.util.Arrays;
public class project2 {
public static void main(String[] args) {
// TODO Auto-generated method stub
String[] array = new String[41];
String[] info = new String[41];
String[] stats = new String[41];
String[] team = new String[41];
//.txt file location
FileInput fileIn = new FileInput();
fileIn.openFile("C:\\Users\\O\\Desktop\\turn in\\team.txt");
// txt file to array
int i = 0;
String line = fileIn.readLine();
array[i] = line;
i++;
while (line != null) {
line = fileIn.readLine();
array[i] = line;
i++;
}
//Splitting up Info/team/score into seprate arrays
for (int j = 0; j < 40; j++) {
team[j] = array[j].substring(0, 3).trim();
info[j] = array[j].substring(3, 30).trim();
stats[j] = array[j].substring(36).trim();
}
// Random stuff i have been trying
System.out.println(team[1]);
System.out.println(info[1]);
System.out.println(stats[1]);
MyObject ob = new MyObject();
ob.setText(info[0]);
ob.setNumber(7, 23);
ob.setNumber(3, 456);
System.out.println("Text is " + ob.getText() + " and number 3 is " + ob.getNumber(7));
}
}
I'm pretty much stuck at this point because I am not sure how to add each teams score together.

This looks like homework... First of all you need to examine how you are parsing the strings in the file.
You're saying: the first 3 characters are the country, which looks correct, but then you set the info to the 4th through the 30th characters, which isn't correct. You need to dynamically figure out where that ends and the score begins. There is a space between the "info" and the "stats," knowing that you could use String's indexOf function. (http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(int))

Have a look at Maps.
A map is a collection that allows you to get data associated with a key in a very short time.
You can create a Map where the key is a country name, with value being the total points.
example:
Map<String,Integer> totalScore = new HashMap<>();
if (totalScore.containsKey("COUNTRYNAME"))
totalScore.put("COUNTRYNAME", totalScore.get("COUNTRYNAME") + playerScore)
else
totalScore.put("COUNTRYNAME",0)
This will add to the country score if the score exists, otherwise it will create a new totalScore for a country initialized to 0.

Not tested, but should give you some ideas:
public static void main(String... args)
throws Exception {
class Structure implements Comparable<Structure> {
private String team;
private String name;
private Double score;
public Structure(String team, String name, Double score) {
this.team = team;
this.name = name;
this.score = score;
}
public String getTeam() {
return team;
}
public String getName() {
return name;
}
public Double getScore() {
return score;
}
#Override
public int compareTo(Structure o) {
return this.score.compareTo(o.score);
}
}
File file = new File("path to your file");
List<String> lines = Files.readAllLines(Paths.get(file.toURI()), StandardCharsets.UTF_8);
Pattern p = Pattern.compile("(\\d+(?:\\.\\d+))");
List<Structure> structures = new ArrayList<Structure>();
for (String line : lines) {
Matcher m = p.matcher(line);
while (m.find()) {
String number = m.group(1);
String text = line.substring(0, line.indexOf(number) - 1);
double d = Double.parseDouble(number);
String team = text.substring(0, 3);
String name = text.substring(3, text.length());
structures.add(new Structure(team, name, d));
}
}
Collections.sort(structures);
List<Structure> topFive = structures.subList(0, 5);
for (Structure structure : topFive) {
System.out.println("Team: " + structure.getTeam());
System.out.println("Name: " + structure.getName());
System.out.println("Score: " + structure.getScore());
}
}
Just remove <br> from your file.

Loading file into memory
Your string splitting logic looks fine.
Create a class like PlayerData. Create one instance of that class for each row and set all the three fields into that using setters.
Keep adding the PlayerData objects into an array list.
Accumulating
Loop through the arraylist and accumulate the team scores into a hashmap. Create a Map to accumulate the team scores by mapping teamCode to totalScore.
Always store row data in a custom object for each row. String[] for each column is not a good way of holding data in general.

Take a look in File Utils. After that you can extract the content from last space character using String Utils e removing the <br> using it as a key for a TreeMap. Than you can have your itens ordered.
List<String> lines = FileUtils.readLines(yourFile);
Map<String, String> ordered = new TreeMap<>();
for (String s : lines) {
String[] split = s.split(" ");
String name = split[0].trim();
String rate = splt[1].trim().substring(0, key.length - 4);
ordered.put(rate, name);
}
Collection<String> rates = ordered.values(); //names ordered by rate
Of course that you need to adjust the snippet.

incompatible type of double array and properties string.split()

public static void main(String[] args)
{
String input="jack=susan,kathy,bryan;david=stephen,jack;murphy=bruce,simon,mary";
String[][] family = new String[50][50];
//assign family and children to data by ;
StringTokenizer p = new StringTokenizer (input,";");
int no_of_family = input.replaceAll("[^;]","").length();
no_of_family++;
System.out.println("family= "+no_of_family);
String[] data = new String[no_of_family];
int i=0;
while(p.hasMoreTokens())
{
data[i] = p.nextToken();
i++;
}
for (int j=0;j<no_of_family;j++)
{
family[j][0] = data[j].split("=")[0];
//assign child to data by commas
StringTokenizer v = new StringTokenizer (data[j],",");
int no_of_child = data[j].replaceAll("[^,]","").length();
no_of_child++;
System.out.println("data from input = "+data[j]);
for (int k=1;k<=no_of_child;k++)
{
family[j][k]= data[j].split("=")[1].split(",");
System.out.println(family[j][k]);
}
}
}
i have a list of family in input string and i seperate into a family and i wanna do it in double array family[i][j].
my goal is:
family[0][0]=1st father's name
family[0][1]=1st child name
family[0][2]=2nd child name and so on...
family[0][0]=jack
family[0][1]=susan
family[0][2]=kathy
family[0][3]=bryan
family[1][0]=david
family[1][1]=stephen
family[1][2]=jack
family[2][0]=murphy
family[2][1]=bruce
family[2][2]=simon
family[2][3]=mary
but i got the error as title: in compatible types
found:java.lang.String[]
required:java.lang.String
family[j][k]= data[j].split("=")[1].split(",");
what can i do?i need help
nyone know how to use StringTokenizer for this input?

Trying to understand why you can't just use split for your nested operation as well.
For example, something like this should work just fine
for (int j=0;j<no_of_family;j++)
{
String[] familySplit = data[j].split("=");
family[j][0] = familySplit[0];
String[] childrenSplit = familySplit[1].split(",");
for (int k=0;k<childrenSplit.length;k++)
{
family[j][k+1]= childrenSplit[k];
}
}

You are trying to assign an array of strings to a string. Maybe this will make it more clear?
String[] array = data.split("=")[1].split(",");
Now, if you want the first element of that array you can then do:
family[j][k] = array[0];

I always avoid to use arrays directly. They are hard to manipulate versus dynamic list. I implemented the solution using a Map of parent to a list of childrens Map<String, List<String>> (read Map<Parent, List<Children>>).
public static void main(String[] args) {
String input = "jack=susan,kathy,bryan;david=stephen,jack;murphy=bruce,simon,mary";
Map<String, List<String>> parents = new Hashtable<String, List<String>>();
for ( String family : input.split(";")) {
final String parent = family.split("=")[0];
final String allChildrens = family.split("=")[1];
List<String> childrens = new Vector<String>();
for (String children : allChildrens.split(",")) {
childrens.add(children);
}
parents.put(parent, childrens);
}
System.out.println(parents);
}
The output is this:
{jack=[susan, kathy, bryan], murphy=[bruce, simon, mary], david=[stephen, jack]}
With this method you can directory access to a parent using the map:
System.out.println(parents.get("jack"));
and this output:
[susan, kathy, bryan]