We Keep Coding

How print the entire data structure created with Composite?

I have class-Composite:
public class CompositeText implements ComponentText {
private TypeComponent type;
private String value;
private final List<ComponentText> childComponents;
private CompositeText() {
childComponents = new ArrayList<>();
}
public CompositeText(String value, TypeComponent typeComponent) {
this.value = value;
this.type = typeComponent;
childComponents = new ArrayList<>();
}
#Override
public void add(ComponentText componentText) {
childComponents.add(componentText);
}
#Override
public void remove(ComponentText componentText) {
childComponents.remove(componentText);
}
#Override
public TypeComponent getComponentType() {
return this.type;
}
#Override
public ComponentText getChild(int index) {
return childComponents.get(index);
}
#Override
public int getCountChildElements() {
return childComponents.size();
}
#Override
public int getCountAllElements() {
return childComponents.stream()
.mapToInt(ComponentText::getCountAllElements)
.sum();
}
#Override
public String toString() {
return null;
}
}
I created classes that perform the same action - parsing, parsing text into paragraphs, into sentences, into tokens, into symbols.
public class IntoParagraphParser implements ActionParser {
// call IntoSentenceParser
}
public class IntoSentenceParser implements ActionParser {
// call IntoLexemeParser
}
public class IntoLexemeParser implements ActionParser {
// call IntoSymbolParser
}
public class IntoSymbolParser implements ActionParser {
}
All data is stored in List <ComponentText> childComponents in class-Composite - CompositeText.
How to properly create a method so that it prints all the data that is inside the composite?
I think this will be the method toString() in CompositeText.
Class IntoParagraphParser look:
public class IntoParagraphParser implements ActionParser {
private static final String PARAGRAPH_SPLIT_REGEX = "(?m)(?=^\\s{4})";
private static final IntoParagraphParser paragraphParser = new IntoParagraphParser();
private static final IntoSentenceParser sentenceParser = IntoSentenceParser.getInstance();
private IntoParagraphParser() {
}
public static IntoParagraphParser getInstance() {
return paragraphParser;
}
public ComponentText parse(String text) throws TextException {
ComponentText oneParagraph;
ComponentText componentParagraph = new CompositeText(text, TypeComponent.PARAGRAPH);
String[] arrayParagraph = text.split(PARAGRAPH_SPLIT_REGEX);
for(String element: arrayParagraph) {
oneParagraph = new CompositeText(element, TypeComponent.PARAGRAPH);
oneParagraph.add(sentenceParser.parse(element));
componentParagraph.add(oneParagraph);
}
return componentParagraph;
}
}

Need #Override the method toString() in CompositeText like this:
#Override
public String toString() {
StringBuilder builder = new StringBuilder();
for (ComponentText component : childComponents) {
builder.append(component.toString());
}
return builder.toString();
}
But how to write this code correctly with Stream API?
#Override
public String toString() {
StringBuilder builder = new StringBuilder();
childComponents.stream().map(...????
return builder.toString();
}

How do I set limited generic return type

Taking the following 2 objects, I cant figure out how to make the following work.
public final *Generic SubType* getInfo(){
...
}
First the class I am working with
public class ResultEntry<Type extends ResultType>{
private final Type mType;
private final String mLabel;
private final String mInfo;
private ResultEntry(final Type t, final String label, final String info){
mType = t;
mLabel = label;
mInfo = info;
}
public static ResultEntry<ResultType> newInstance(final String label, final Number info){
return new ResultEntry<>(ResultType.NUMBER, label, info.toString());
}
public static ResultEntry<ResultType> newInstance(final String label, final Boolean info){
return new ResultEntry<>(ResultType.NUMBER, label, info.toString());
}
public static ResultEntry<ResultType> newInstance(final String label, final String info){
return new ResultEntry<>(ResultType.NUMBER, label, info);
}
public final ResultType getType(){
return mType;
}
public final String getLabel(){
return mLabel;
}
public final *Generic SybType* getInfo(){
}
}
And then enum ResultType
public enum ResultType {
STRING ("STRING"),
BOOLEAN ("BOOLEAN"),
NUMBER ("NUMBER");
private final String s;
ResultType(final String string){
s = string;
}
public final boolean isString(){
return s.equals(STRING.s);
}
public final boolean isBoolean(){
return s.equals(BOOLEAN.s);
}
public final boolean isNumber(){
return s.equals(NUMBER.s);
}
}
What I would like to do is have a way to check what mType is (String, Boolean, or Number) and then return that actual object. Something like,
public final *Generic SubType* getInfo(){
if(mType.isString()) return new String();
if(mType.isNumber()) return new Number();
if(mType.isBoolean()) return new Boolean();
}
Though obviously I would have actual information to pass back instead.
But I dont know if that is possible, and if so, I don't know how I would go about doing it. It does appear that Android is able to do it via AsyncTask.
For reference, I found most of this from This Question

I would suggest you do it like this, which doesn't convert the info values to String, i.e. mInfo is Object, not String.
public class ResultEntry<R> {
private final ResultType mType;
private final String mLabel;
private final Object mInfo;
private ResultEntry(final ResultType t, final String label, final Object info) {
this.mType = t;
this.mLabel = label;
this.mInfo = info;
}
public static ResultEntry<Number> newInstance(final String label, final Number info) {
return new ResultEntry<>(ResultType.NUMBER, label, info);
}
public static ResultEntry<Boolean> newInstance(final String label, final Boolean info) {
return new ResultEntry<>(ResultType.BOOLEAN, label, info);
}
public static ResultEntry<String> newInstance(final String label, final String info) {
return new ResultEntry<>(ResultType.STRING, label, info);
}
public final ResultType getType() {
return this.mType;
}
public final String getLabel() {
return this.mLabel;
}
#SuppressWarnings("unchecked")
public final R getInfo() {
return (R) this.mInfo;
}
}
Then you use it like this:
ResultEntry<Number> numEntry = ResultEntry.newInstance("", 5);
ResultEntry<Boolean> boolEntry = ResultEntry.newInstance("", true);
ResultEntry<String> strEntry = ResultEntry.newInstance("", "Foo");
Number numInfo = numEntry.getInfo();
Boolean boolInfo = boolEntry.getInfo();
String strInfo = strEntry.getInfo();

Error with writing to a file in Java [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 4 years ago.
I am getting the following errors.
Exception in thread "main" java.lang.NullPointerException at ReadFile.createDogs(ReadFile.java:41) at ReadFile.main(ReadFile.java:55)
The file is opening to the desktop. I feel I am missing something very
simple. I have included the class file also. The error is specific to
dogOutput.println(dogInfo);
Thank you.
import java.io.*;
import java.io.PrintWriter;
public class ReadFile
{
private static Canine[] getCanine()
{
Canine[] canines= new Canine[5];
canines[0]=new Canine("Thoedore", "Male", "Medium", 7, 50);
canines[1]=new Canine("Magellan", "Male", "Medium", 5, 50);
canines[2]=new Canine("Duffy", "Male", "Small", 10, 10);
canines[3]=new Canine("Sammie", "Female", "Medium", 7, 65);
canines[4]=new Canine("Snowball", "Male", "Small", 13, 17);
return canines;
}
private static PrintWriter createFile(String fileName)
{
try{
File listOfDogs = new File(fileName);
PrintWriter infoToWrite= new PrintWriter
( new BufferedWriter
(new FileWriter(listOfDogs)));
}
catch (IOException e)
{
System.out.println(" An I/O Error Occurred.");
System.exit(0);
}
return null;
}
private static void createDogs(Canine dog, PrintWriter dogOutput)
{
String dogInfo= dog.name + " " + dog.gender+ " " + dog.size +" ";
dogInfo += Integer.toString(dog.age)+ " "+
Double.toString(dog.weight);
dogOutput.println(dogInfo);
}
public static void main (String[] args)
{
Canine[] canines= getCanine();
System.out.println("Here1");
PrintWriter dogOutput =
createFile("/Users/Teacher/Desktop/Dogs.text");
for(Canine dogs: canines)
{
createDogs(dogs, dogOutput);
System.out.println("Here5");
}
dogOutput.close();
}
private static class Canine extends Pet
{
public static final String type="Dog";
public Canine()
{
super.type=this.type;
}
public Canine(String name, String gender, String size, int age, double
weight)
{
super.type=this.type;
super.name=name;
super.gender=gender;
super.size=size;
super.age=age;
super.weight=weight;
}
public static void setType(String word)
{
}
}
private static class Pet
{
public static String type;
public static String color;
public static String gender;
public static String temperment;
public static String food;
public static int age;
public static double weight;
public static String name;
public static String size;
public Pet()
{
}
public Pet(String type,String color,String gender,String temperment,
String food,int age,double weight,String name,String size)
{
type=type;
color=color;
gender=gender;
temperment=temperment;
food=food;
age=age;
weight=weight;
name=name;
size=size;
}
public Pet(String name, String gender, String size, int age, double
weight)
{
name=name;
gender=gender;
size=size;
age=age;
weight=weight;
}
public static String getType()
{
return type;
}
public static String getName()
{
return name;
}
public static String getSize()
{
return size;
}
public static String getColor()
{
return color;
}
public static String getTemperment()
{
return temperment;
}
public static String getFood()
{
return food;
}
public static String getGender()
{
return gender;
}
public static int getAge()
{
return age;
}
public static void setType(String word)
{
type=word;
}
public static void getName(String word)
{
name=word;
}
public static void setSize(String word)
{
size=word;
}
public static void setColor(String word)
{
color=word;
}
public static void getTemperment(String word)
{
temperment=word;
}
public static void setFood(String word)
{
food=word;
}
public static void setGender(String word)
{
gender=word;
}
public static void setAge(int ageSet)
{
age=ageSet;
}
public static void setWeight(double weightSet)
{
weight=weightSet;
}
public static void setName(String NameSet)
{
name=NameSet;
}
public String toString()
{
return ("Type "+type+"\n" +" Name "+name+"\n"+" Age "+age+"\n"+
"Size "+ size+"\n"+" Gender "+gender+"\n"+" Weight "+weight);
}
}
}

Try renaming the dogOutput variable. In java, you can't pass variables between static methods with the same name.

The simple answer: In createFile() you always return null instead of the instance of PrintWriter you just created as infoToWrite.
The complete answer: You need to strengthen your knowledge of OOP. The unnecessary use of static members, for instance, can have undesired effects.

DataFlavor custom class usage

I want to create a custom dataFlavor with my class (Item.class)
#Override
public synchronized void drop(DropTargetDropEvent dtde) {
DataFlavor itemFlavor = new DataFlavor(Item.class, Item.class.getSimpleName());
try{
System.out.println(dtde.getTransferable().getTransferData(itemFlavor));
}catch(UnsupportedFlavorException | IOException e){
e.printStackTrace();
}
}
Item.class
public class Item {
private String classFile;
private String imgFile;
private String imgPath;
public Item(String classFile, String imgFile, String imgPath){
this.classFile = classFile;
this.imgFile = imgFile;
this.imgPath = imgPath;
}
public String getImgFile() {
return imgFile;
}
public void setImgFile(String imgFile) {
this.imgFile = imgFile;
}
public String getClassFile() {
return classFile;
}
public void setClassFile(String classFile) {
this.classFile = classFile;
}
public String getImgPath() {
return imgPath;
}
public void setImgPath(String imgPath) {
this.imgPath = imgPath;
}
}
but I'm getting an error: java.awt.datatransfer.UnsupportedFlavorException: Item
Can you say what is wrong ?
I were using this docs https://docs.oracle.com/javase/tutorial/uiswing/dnd/dataflavor.html
Example, that demonstrate the problem DND Test Project
To get an error, try drag from JTable to JLayeredPane

how to implement Parcelable in android?

can you please tell me how to implement Parcelable in android? Actually I want to send an array list from one activity to another. So I google find in need to Parcelable the dot or model. But I have object of another class so how do I write in Parcelable? In other word
I have this object
DestinationStation destinationStation;
what should i write in this function public void writeToParcel
dest.writeString(destinationStation);
here is my code of both class
public class deparaturedaseboarddto implements Parcelable{
ArrayList<deparaturedaseboarddto> data;
public ArrayList<deparaturedaseboarddto> getData() {
return data;
}
public void setData(ArrayList<deparaturedaseboarddto> data) {
this.data = data;
}
#SerializedName("alertsId")
int alertsId;
#SerializedName("destExpArrival")
String destExpArrival;
#SerializedName("destSchArrival")
String destSchArrival;
#SerializedName("expDepart")
String expDepart;
#SerializedName("filteredStation")
String filteredStation;
#SerializedName("platformNo")
String platformNo;
#SerializedName("rid")
String rid;
#SerializedName("schDepart")
String schDepart;
#SerializedName("toc")
String toc;
#SerializedName("toExpArrival")
String toExpArrival;
#SerializedName("toSchArrival")
String toSchArrival;
#SerializedName("trainID")
String trainID;
#SerializedName("trainLastReportedAt")
String trainLastReportedAt;
#SerializedName("destinationStation")
DestinationStation destinationStation;
public deparaturedaseboarddto(String trainID,String toc,String trainLastReportedAt, String platformNo, String schDepart, String expDepart, int alertsId, String rid, String destSchArrival, String filteredStation, String destExpArrival, String toSchArrival, String toExpArrival,DestinationStation destinationStation){
super();
this.trainID=trainID;
this.toc=toc;
this.trainLastReportedAt=trainLastReportedAt;
this.platformNo=platformNo;
this.schDepart=schDepart;
this.expDepart=expDepart;
this.alertsId=alertsId;
this.destinationStation=destinationStation;
this.toExpArrival=toExpArrival;
this.toSchArrival=toSchArrival;
this.destExpArrival=destExpArrival;
this.filteredStation=filteredStation;
this.destSchArrival=destSchArrival;
this.rid=rid;
}
public DestinationStation getDestinationStation() {
return destinationStation;
}
public void setDestinationStation(DestinationStation destinationStation) {
this.destinationStation = destinationStation;
}
public int getAlertsId() {
return alertsId;
}
public void setAlertsId(int alertsId) {
this.alertsId = alertsId;
}
public String getDestExpArrival() {
return destExpArrival;
}
public void setDestExpArrival(String destExpArrival) {
this.destExpArrival = destExpArrival;
}
public String getDestSchArrival() {
return destSchArrival;
}
public void setDestSchArrival(String destSchArrival) {
this.destSchArrival = destSchArrival;
}
public String getExpDepart() {
return expDepart;
}
public void setExpDepart(String expDepart) {
this.expDepart = expDepart;
}
public String getFilteredStation() {
return filteredStation;
}
public void setFilteredStation(String filteredStation) {
this.filteredStation = filteredStation;
}
public String getPlatformNo() {
return platformNo;
}
public void setPlatformNo(String platformNo) {
this.platformNo = platformNo;
}
public String getRid() {
return rid;
}
public void setRid(String rid) {
this.rid = rid;
}
public String getSchDepart() {
return schDepart;
}
public void setSchDepart(String schDepart) {
this.schDepart = schDepart;
}
public String getToc() {
return toc;
}
public void setToc(String toc) {
this.toc = toc;
}
public String getToExpArrival() {
return toExpArrival;
}
public void setToExpArrival(String toExpArrival) {
this.toExpArrival = toExpArrival;
}
public String getToSchArrival() {
return toSchArrival;
}
public void setToSchArrival(String toSchArrival) {
this.toSchArrival = toSchArrival;
}
public String getTrainID() {
return trainID;
}
public void setTrainID(String trainID) {
this.trainID = trainID;
}
public String getTrainLastReportedAt() {
return trainLastReportedAt;
}
public void setTrainLastReportedAt(String trainLastReportedAt) {
this.trainLastReportedAt = trainLastReportedAt;
}
#Override
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(alertsId);
dest.writeString(destExpArrival);
dest.writeString(destSchArrival);
dest.writeString(expDepart);
dest.writeString(filteredStation);
dest.writeString(platformNo);
dest.writeString(rid);
dest.writeString(schDepart);
dest.writeString(toc);
dest.writeString(toExpArrival);
dest.writeString(toSchArrival);
dest.writeString(trainID);
dest.writeString(trainLastReportedAt);
dest.writeString(destinationStation);
}
public static final Parcelable.Creator<deparaturedaseboarddto> CREATOR = new Parcelable.Creator<deparaturedaseboarddto>() {
public deparaturedaseboarddto createFromParcel(Parcel in) {
return new deparaturedaseboarddto(in);
}
public deparaturedaseboarddto[] newArray(int size) {
return new deparaturedaseboarddto[size];
}
};
private deparaturedaseboarddto(Parcel in) {
this.alertsId=in.readInt();
this.destExpArrival=in.readString();
this.destSchArrival=in.readString();
this.expDepart=in.readString();
this.filteredStation=in.readString();
this.platformNo=in.readString();
this.rid=in.readString();
this.schDepart=in.readString();
this.toc=in.readString();
this.toExpArrival=in.readString();
this.toSchArrival=in.readString();
this.trainID=in.readString();
this.trainLastReportedAt=in.readString();
}
}
destinationstation:
import com.google.gson.annotations.SerializedName;
public class DestinationStation implements Parcelable {
#SerializedName("crsCode")
String crsCode;
#SerializedName("stationName")
String stationName;
public DestinationStation(String crsCode, String stationName) {
// TODO Auto-generated constructor stub
super();
this.crsCode=crsCode;
this.stationName=stationName;
}
public String getCrsCode() {
return crsCode;
}
public void setCrsCode(String crsCode) {
this.crsCode = crsCode;
}
public String getStationName() {
return stationName;
}
public void setStationName(String stationName) {
this.stationName = stationName;
}
#Override
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(crsCode);
dest.writeString(stationName);
}
public static final Parcelable.Creator<DestinationStation> CREATOR = new Parcelable.Creator<DestinationStation>() {
public DestinationStation createFromParcel(Parcel in) {
return new DestinationStation(in);
}
public DestinationStation[] newArray(int size) {
return new DestinationStation[size];
}
};
private DestinationStation(Parcel in) {
this.crsCode=in.readString();
this.stationName=in.readString();
}
}
I am getting error in this line
dest.writeString(destinationStation);
Could you please tell how to remove this error?