Develop Reference

I am not correctly reading from the text file into an ArrayList after parsing each line into an object

I am trying to read from the txt file and then parse through it and make each line a new object in an ArrayList. I keeps telling me its null and I cannot figure out why. I have not used java in a long time so I'm sure its dumb.
public class AccessibilityTest {
private String cat;
private String googErr;
private String waveErr;
private String sortErr;
private String lintErr;
private String desc;
public AccessibilityTest(String cat,String googErr,String waveErr,String sortErr,String lintErr, String desc){
this.cat = cat;
this.googErr = googErr;
this.waveErr = waveErr;
this.sortErr = sortErr;
this.lintErr = lintErr;
this.desc = desc;
}
public static void main(String[] args) {
AccessibilityResults.readTxtFile("a11yCheckersResults.txt");//this is one place im getting the error and its me trying to target that txt file
System.out.println();
}
public String getCategory() {
return cat;
}
public String getGoogleResult() {
return googErr;
}
public String getWaveResult() {
return waveErr;
}
public String getSortsiteResult() {
return sortErr;
}
public String getAslintResult() {
return lintErr;
}
public String getDescription() {
return desc;
}
#Override
public String toString(){
return "fsdfse"+ getCategory() + getGoogleResult()+ getWaveResult()+ getSortsiteResult() + getAslintResult() + getDescription();
}
}
This is the other file where I am actually parsing through the txt file and creating the objects.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.*;
public class AccessibilityResults {
private static ArrayList<AccessibilityTest> list;
public AccessibilityResults() {
list = new ArrayList<>();
}
public static void readTxtFile(String fileName){
try(Scanner reader = new Scanner(new File(fileName))){
while(reader.hasNextLine()){
String cat = reader.next();
String err1 = reader.next();
String err2 = reader.next();
String err3 = reader.next();
String err4 = reader.next();
String desc = reader.nextLine();
list.add(new AccessibilityTest(cat, err1, err2, err3, err4,desc));//this is one spot im getting the error
}
} catch(FileNotFoundException e){
System.out.println("File not found: " + fileName);
}`enter code here`
}
}
//txt file
//a11yCheckersResults.txt

The reason is that list and readTxtFile is static method,but the readTxtFile() that init list is not static,and in java static properties and method will be inited before none static which cause it
To solve it,there are several options:
one option is just to remove all the static in list and readTxtFile(),another options is just init list when declare it private static ArrayList<AccessibilityTest> list = new ArrayList<>();
// static
private static ArrayList<AccessibilityTest> list;
// no static,so list will always be null
public AccessibilityResults() {
list = new ArrayList<>();
}
// static
public static void readTxtFile(String fileName){
try(Scanner reader = new Scanner(new File(fileName))){
while(reader.hasNextLine()){
String cat = reader.next();
String err1 = reader.next();
String err2 = reader.next();
String err3 = reader.next();
String err4 = reader.next();
String desc = reader.nextLine();
list.add(new AccessibilityTest(cat, err1, err2, err3, err4,desc));//this is one spot im getting the error
}
} catch(FileNotFoundException e){
System.out.println("File not found: " + fileName);
}
}
}

How to get user input and store in custom object? JAVA

Henlo,
Basically what im trying to do is get user inputs and store in a custom object but I have no idea on how to go about it. I have created a loadDataFromConfig() method? that works fine when creating the object SmartHome app = new SmartHome(loadDataFromConfig());.
But I am completely stumped on how to get user inputs and store them in this format: dev[0] = new SmartDevice("device 1",1.3,true);.
All the code that is meant to run should be inside the main method in Step1.java
Here are the 3 classes used for the code (ignore comments they are just notes for me):
package SmartHomeApp;
public class SmartDevice {
private String name;
private double location;
private boolean switchedOn;
public SmartDevice(String val1, double val2, boolean val3) {
setName(val1);
setLocation(val2);
setSwitchedOn(val3);
}
//YOU CANT ACCESS the 'private classes' so you need to GET them
public void setName(String value) {name = value;}
public void setLocation(double value) {location = value;}
public void setSwitchedOn(boolean value) {switchedOn = value;}
public String getName() {return name;}
public double getLocation() {return location;}
public boolean getSwitchedOn() {return switchedOn;}
}
package SmartHomeApp;
public class SmartHome
{
private SmartDevice[] smrtDev;
public SmartHome(int size) {
smrtDev = new SmartDevice[size];
}
public SmartHome(SmartDevice[] values) {
smrtDev = values;
}
public int size() {return smrtDev.length;}
// can't do toString() for some reason??
public void ToString() {
for(int i=0; i<size();i++)
{
if(smrtDev[i] != null ){
System.out.println("----------");
System.out.println("-DEVICE "+(i+1)+"-");
System.out.println("----------");
System.out.println("Name: "+smrtDev[i].getName());
System.out.println("Location: "+smrtDev[i].getLocation());
System.out.println("Switched On: "+smrtDev[i].getSwitchedOn());
}
}
}
}
package SmartHomeApp;
import java.util.*;
public class Step1 {
public static void main(String args[]) {
SmartHome app = new SmartHome(loadDataFromConfig());
app.ToString();
}
public static SmartDevice[] loadDataFromConfig()
{
SmartDevice[] dev = new SmartDevice[20];
dev[0] = new SmartDevice("device 1",1.3,true);
dev[1] = new SmartDevice("device 2",2.3,false);
dev[2] = new SmartDevice("device 3",3.3,true);
dev[4] = new SmartDevice("device 5",4.3,false);
dev[19] = new SmartDevice("device 20",5.3,false);
return dev;
}
}

Some of the improvements required in your code are as follows:
Follow Java naming conventions e.g. ToString() should be toString(). Check this to learn more about toString(). Most of the IDEs (e.g. eclipse) provide a feature to generate toString() method on click of a button. Whatever way (either manual or with the help of your IDE) you generate it, it must return a String.
You should do away with using next(), nextInt(), nextDouble() etc. and use nextLine() instead. Check this to learn more it. To give you an idea what problems next(), nextDouble() can cause, try entering a name with a space e.g.
Enter size:
2
Name:
Light Amplification by Stimulated Emission of Radiation
Location:
Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Scanner.java:939)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextDouble(Scanner.java:2564)
at Main.main(Main.java:83)
Given below is a sample code incorporating the improvements mentioned above:
import java.util.Scanner;
class SmartDevice {
private String name;
private double location;
private boolean switchedOn;
public SmartDevice(String val1, double val2, boolean val3) {
setName(val1);
setLocation(val2);
setSwitchedOn(val3);
}
// YOU CANT ACCESS the 'private classes' so you need to GET them
public void setName(String value) {
name = value;
}
public void setLocation(double value) {
location = value;
}
public void setSwitchedOn(boolean value) {
switchedOn = value;
}
public String getName() {
return name;
}
public double getLocation() {
return location;
}
public boolean getSwitchedOn() {
return switchedOn;
}
#Override
public String toString() {
return "SmartDevice [name=" + name + ", location=" + location + ", switchedOn=" + switchedOn + "]";
}
}
class SmartHome {
private SmartDevice[] smrtDev;
public SmartHome(int size) {
smrtDev = new SmartDevice[size];
}
public SmartHome(SmartDevice[] values) {
smrtDev = values;
}
public int size() {
return smrtDev.length;
}
#Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (SmartDevice smartDevice : smrtDev) {
sb.append(smartDevice.toString()).append("\n");
}
return sb.toString();
}
}
public class Main {
public static void main(String[] args) {
Scanner myObj = new Scanner(System.in);
int size = getPositiveInt(myObj, "Enter size: ");
SmartDevice[] newList = new SmartDevice[size];
for (int i = 0; i < newList.length; i++) {
System.out.print("Name: ");
String x = myObj.nextLine();
double y = getFloatingPointNumber(myObj, "Location: ");
boolean z = getBoolean(myObj, "Is on?: ");
newList[i] = new SmartDevice(x, y, z);
}
SmartHome newDevice = new SmartHome(newList);
System.out.println(newDevice);
}
static int getPositiveInt(Scanner in, String message) {
boolean valid;
int n = 0;
do {
valid = true;
System.out.print(message);
try {
n = Integer.parseInt(in.nextLine());
if (n <= 0) {
throw new IllegalArgumentException();
}
} catch (IllegalArgumentException e) {
System.out.println("This in not a positive integer. Please try again.");
valid = false;
}
} while (!valid);
return n;
}
static double getFloatingPointNumber(Scanner in, String message) {
boolean valid;
double n = 0;
do {
valid = true;
System.out.print(message);
try {
n = Double.parseDouble(in.nextLine());
} catch (NumberFormatException | NullPointerException e) {
System.out.println("This in not a number. Please try again.");
valid = false;
}
} while (!valid);
return n;
}
static boolean getBoolean(Scanner in, String message) {
System.out.print(message);
return Boolean.parseBoolean(in.nextLine());
}
}
A sample run:
Enter size: x
This in not a positive integer. Please try again.
Enter size: -2
This in not a positive integer. Please try again.
Enter size: 10.5
This in not a positive integer. Please try again.
Enter size: 2
Name: Light Amplification by Stimulated Emission of Radiation
Location: 123.456
Is on?: true
Name: Vacuum Diode
Location: 234.567
Is on?: no
SmartDevice [name=Light Amplification by Stimulated Emission of Radiation, location=123.456, switchedOn=true]
SmartDevice [name=Vacuum Diode, location=234.567, switchedOn=false]

So as suggested I tried to do the following:
public static void main(String args[]) {
Scanner myObj = new Scanner(System.in);
System.out.println("Enter size: ");
int size = myObj.nextInt();
SmartDevice[] newList = new SmartDevice[size];
for(int i =0; i<newList.length;i++) {
System.out.println("Name: ");
String x = myObj.next();
System.out.println("Location: ");
double y = myObj.nextDouble();
System.out.println("Is on?: ");
boolean z = myObj.nextBoolean();
newList[i] = new SmartDevice(x,y,z);
}
SmartHome newDevice = new SmartHome(newList);
newDevice.ToString();
}
Got it working but not sure if this is the most efficient way to do so??

Sorting of ArrayList<Track>

I want to sort ArrayList according to artist's name I have used comparator interface but I'm not able to sort the list. So kindly help me to solve the problem. The track data will be read from a file Trackdump. The file would contain one track data per line in the format TITLE/ARTIST/RATING/BPM
Here is the code:
import java.io.*;
import java.util.*;
public class MusicLibrary {
ArrayList<Track> songList = new ArrayList<Track>();
public static void main(String args[]) {
new MusicLibrary().go();
}
public void go() {
System.out.println("go");
getTracks();
System.out.println("Before Sorting:");
System.out.println(songList);
Collections.sort(songList);
System.out.println("Sorted according to Artist's name:");
System.out.println(songList);
}
void getTracks() {
System.out.println("gt");
File file = new File("TrackDump.txt");
try{
BufferedReader readr = new BufferedReader(new FileReader(file));
String line = null;
System.out.println(readr);
while ((line = readr.readLine()) != null) {
System.out.println(line);
addSong(line);
}
}catch(Exception e){
e.printStackTrace();
}
}
void addSong(String lineToParse) {
String[] tokens = lineToParse.split("/");
Track nextSong = new Track(tokens[0], tokens[1], tokens[2], tokens[3]);
songList.add(nextSong);
System.out.println(songList);
}
}
class Track implements Comparator<Track>
{
String title;
String artist;
String rating;
String bpm;
public int compare(Track o1, Track o2) {
return o1.getArtist().compareTo(o2.getArtist());
}
public Track(String a, String t, String r, String b) {
title = t;
artist = a;
rating = r;
bpm = b;
}
public boolean equals(Object aSong) {
return this.equals(aSong);
}
public String getArtist() {
return artist;
}
public String getBpm() {
return bpm;
}
public String getRating() {
return rating;
}
public String getTitle() {
return title;
}
public String toString() {
return title + "-" + artist;
}
}
Trackdump:
Title1/Artist1/8/320
Title2/Artist2/10/48
T5/A7/10/120
Title4/A7/9/240
T7/Artist5/7/320
Title6/Artist6/3/240
T9/A7/1/550
T6/Artist8/5/120
T1/Artist9/5/290
Song2/A0/5/320
Song5/A8/10/320
Song1/A2/6/290

You have to implement Comparable class to your Track class. Not Comparator. Then override compareTo() method. It would look like this:
public class Track implements Comparable<Track> {
// Variables, constructor, getters, setters ...
#Override
public int compareTo(Track other) {
return this.getArtist().compareTo(other.getArtist());
}
}
Finally sort with Collections.sort();

You need to implement the Comparable interface and then you can use Collections.sort().
class Track implements Comparable<Track> {
String title;
String artist;
String rating;
String bpm;
#Override
public int compare(Track other) {
return this.getArtist().compareTo(other.getArtist());
}
...
In theory it would work too when implementing Comparator but then you have to pass a Track object into Collections.sort() to act as the Comparator. But that is a rather weird way of doing it so better use the solution above.
Collections.sort(songList, new Track(null, null, null, null));

Array outputs random sequence of characters instead of desired result

I am attempting to write a program that will output data received from a csv file. The CSV file is composed of 28 or so strings/lines with each data in the line separated by a comma into 5 categories (Team name, League, Coaches, Division and Full Time).
I actually have a couple of issues...
When i run my program, i receive a random sequence of characters (such as: [Ljava.lang.String;#5e34d46a) in my coaches category instead of a name that i am expecting. Does this have something to do with it being in an array? How would i solve it.
The categories for each string are displayed in the output as a list, i would like to output the data of strings into a line. For example, instead of the output displaying:
Team name: Team A
League: Western Conference
Coaches: [Ljava.lang.String;#1c751d58
Division: 2
Full Time: true
I would like it to be displayed as a line.
The last category of a single instance of a string in the output is attached to the first category of the next string. Like so: Full Time: trueTeam name: Team A. How would i separate this?
My Team.java code:
public class Team
{
private String name;
private String league;
private String[] coaches;
private String division;
private boolean fullTime;
public Team(String dataLine)
{
String[] data = dataLine.split(",");
this.name = data[0];
this.coaches = getStringAsArray(data[1], ":");
this.league = data[2];
this.division = data[3];
this.fullTime = data[4].equals("yes");
}
public Team(){
}
private String[] getStringAsArray(String t, String delimiter)
{
String[] result = t.split(delimiter);
return result;
}
private String getArrayAsString(String[] coaches)
{
coaches = this.getCoaches();
String result = "";
for(int i = 0; i<coaches.length; i++)
{
result += coaches[i] +" ";
}
result = result.trim();
return result;
}
public void setName(String name)
{
this.name = name;
}
public String getName()
{
return this.name;
}
public void setCoaches(String coaches)
{
this.coaches = getStringAsArray(coaches, ":");
}
public String getCoachesAsString()
{
String result = getArrayAsString(coaches);
return result;
}
public boolean isFullTime() {
return fullTime;
}
public void setFullTime(boolean fullTime) {
this.fullTime = fullTime;
}
public String getDivision() {
return division;
}
public void setDivision(String division) {
this.division = division;
}
public String[] getCoaches() {
return coaches;
}
public void setCoaches(String[] coaches) {
this.coaches = coaches;
}
public String getLeague() {
return league;
}
public void setLeague(String league) {
this.league = league;
}
#Override
public String toString() {
return "Team name: " + name + "\nLeague: " + this.league + "\nCoaches: " + this.coaches + "\nDivision: " + this.division + "\nFull Time: " + this.fullTime;
}
}
My StoreData.java code:
import shiftershape.model.Team;
import java.util.ArrayList;
public class StoreData {
public static ArrayList<Team> teams = new ArrayList<Team>();
public static String getTeams()
{
String s = "";
for(int i = 0; i < teams.size(); i++){
s += teams.get(i);
}
return s;
}
public static ArrayList<Team> TeamListFromArray(String[] as)
{
ArrayList<Team> teams = new ArrayList<Team>();
// for( int i= 0 ; i < as.length; i++){
for (String s: as){
teams.add(new Team(s));
}
return teams;
}
}
My ReadCSV.java code:
import Utilities.StoreData;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import shiftershape.model.Team;
public class ReadCsv {
public void readCsv() {
String csvFileToRead = "C:/Users/Fryyy/Desktop/FootballRepo/TestData/football_teams_phase1.csv";
BufferedReader br = null;
String line = "";
try {
br = new BufferedReader(new FileReader(csvFileToRead));
int i = 0;
while ((line = br.readLine()) != null) {
Team one = new Team(line);
if(i > 0){
StoreData.teams.add(new Team(line));
}else{
i++;
}
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static ArrayList<Team> getTeams() {
return StoreData.teams;
}
public static void setTeams(ArrayList<Team> teams) {
StoreData.teams = teams;
}
}
My FootballC.java code:
import Utilities.StoreData;
import shiftershape.model.Team;
public class FootballC {
public static void main(String[] args)
{
ReadCsv junk = new ReadCsv();
junk.readCsv();
System.out.println(StoreData.getTeams());
}
}

System.out.println(StoreData.getTeams()); will call toString() on String[]
try this:
for (String s : StoreData.getTeams()) {
System.out.println(s);
}

[Ljava.lang.String;#5e34d46a) is the resource code for an object when printed to standard out. In this case being a string, so somewhere it looks like you're printing an array instead of the value within the array, causing the resource ID to be shown instead of the values within, as Java doesn't print array contents by default.

[Ljava.lang.String;#1c751d58 is the String version of an array. Arrays don't have a nice toString() method. If you used Lists in stead of Arrays it will print better.
The quick conversion of an array to a list is Arrays.asList(array);

need to split the string using get() and set() methods

I have to use getters and setters for this code and
actually i'm using two classes to get the result
here is Ndc class:
package java4u.com;
public class Ndc {
private String ndcQUAL;
private String ndcCODE;
private String ndcUNIT;
private String ndcQTY;
String str;
public String getStr() {
return str;
}
public void setStr(String str) {
this.str = str;
}
public String getndcQUAL() {
if(str.contains("N4"))
{
return "N4";
}
else
{
return "";
}
}
public void setndcQUAL(String getndcQUAL) {
this.ndcQUAL = getndcQUAL;
}
public String getndcCODE() {
if(str.contains("N4")){
int i=str.indexOf("N4");
str=str.substring(i+2,i+13);
return str;
}
else
{
return "";
}
}
public void setndcCODE(String getndcCODE) {
this.ndcCODE = getndcCODE;
}
public String getndcUNIT() {
if(str.contains("N4")) {
str=str.substring(i+13,i+15);
return str;
}else
{
return "";
}
}
public void setndcUNIT(String getndcUNIT) {
this.ndcUNIT = getndcUNIT;
}
public String getndcQTY() {
if(str.contains("N4")) {
do {
int i=str.indexOf(getndcUNIT());
str=str.substring(i,i++);
return str;
} while(str.length()<=35 || str.contains("N4") || str.contains("TPL"));
else
{
return "";
}
}
public void setndcQTY(String getndcQTY) {
this.ndcQTY = getndcQTY;
}
}
here i'm using str variable and the string will be entered during runtime and the condition is if string contains "N4" value then the loop should be continue else return space.
and I have four methods in this program and
getNdcQUAL() method should return "N4" if string contains "N4" value
and getNdcCODE() method should display next 11 digits after the "N4" for this case I shouldn't mention str.substring(2,13)..I should find the position of NdcQUAL and from there to next 11 digits will be print..
and getNdcUNIT() method should display next two bytes qualifier after the 11 digits for this case also I should find the position of NdcCODE and from there to 2 digits
and finally getNdcQTY() method should return the data after the NdcUNIT for this case also I should find the position of NdcUNIT and from there to untill one of the condition is met
here is my main class
package java4u.com;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import com.sun.xml.internal.bind.v2.runtime.reflect.Accessor.GetterSetterReflection;
public class Test {
public static String getStr(String str)
{
return str;
}
public static void main(String args[]) {
Ndc ndc=new Ndc();
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
try {
System.out.println("enter a string:");
br.readLine();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
couldn't understand how to pass the string value from Ndc.java to Test.java also couldn't get how to pass other methods from Ndc.java to Test.java
here is the sample output
str=N412345678923UN2345.677
it should return
N4
12345678923
UN
2345.67
please help me!!!!!!

Since you don't have a constructor. You need to manually set the str
If this N412345678923UN2345.677 is the br.readLine(). Then you need to set it in the for your NDC object
String str = br.readLine();
ndc.setStr(str); // now the str is set in your ndc object.
System.out.println(ndc.getndcCODE());
System.out.println(ndc.getndcUNIT());
System.out.println(ndc.getndcCQTY());

You should first pass the string like this :
ndc.setndcQUAL(yourString);
then get the required value :
System.out.print(ndc.getndcQUAL());

Your approach has one major flaw - you need to execute the methods in a predefined order, else it will extract wrong data. You can however use your setStr(String str) method to initialize all proper fields and then just use your getter methods to return the values you've set within your setStr(...) method:
public class Ndc
{
private String ndcQUAL;
private String ndcCODE;
private String ndcUNIT;
private String ndcQTY;
public void setStr(String str)
{
int pos = 0;
if (str.contains("N4"))
{
pos = str.indexOf("N4");
this.ndcQUAL = str.substring(pos, pos+=2);
this.ndcCODE = str.substring(pos, pos+=11);
this.ndcUNIT = str.substring(pos, pos+=2);
String data = str.substring(pos);
// trim the data at the end corresponding to the provided class logic
int p = data.length();
if (data.contains("N4"))
{
p = data.indexOf("N4");
}
else if (data.contains("TLP"))
{
p = data.indexOf("TLP");
}
if (p > 35)
p = 35;
this.ndcQTY = data.substring(0, p);
}
else
this.ndcQUAL = "";
}
public String getndcQUAL()
{
return this.ndcQUAL;
}
public String getndcCODE()
{
return this.ndcCODE;
}
public String getndcUNIT()
{
return this.ndcUNIT;
}
public String getndcQTY()
{
return this.ndcQTY;
}
}
To break the loop if no valid N4 string was entered, you first have to define a kind of loop first and check the getndcQUAL() return value if it equals N4 after you've assigned the input string to setStr(...):
public class Test
{
public static void main(String args[])
{
Ndc ndc=new Ndc();
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
try
{
do
{
System.out.println("enter a string:");
ndc.setStr(br.readLine());
System.out.println("QUAL: "+ndc.getndcQUAL());
System.out.println("CODE: "+ndc.getndcCODE());
System.out.println("UNIT: "+ndc.getndcUNIT());
System.out.println("QTY: "+ndc.getndcQTY());
}
while("N4".equals(ndc.getndcQUAL()));
}
catch (IOException e)
{
e.printStackTrace();
}
}
}