I need to implement a method called saveWorksToFile according to the Javadoc in the code. The format of the output written to the file should be the following this pattern:
where ARTIST_NAME is the name of the artist, NUM_WORKS is the number of works of that artist, and WORK_1, WORK_2, etc. are the toString representations of each of that artist’s works.
The last work should not have a line separator after it.
If an artist has no works, then the first three lines of the above format should be written, where the “—–” line has a line separator after it.
And this is the code I have:
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.StringJoiner;
public class Artist {
static class Work {
String name; // e.g. "Mona Lisa"
int yearCreated; // e.g. 1506
String medium; // e.g. "Oil on poplar panel"
public Work(String name, int yearCreated, String medium) {
this.name = name;
this.yearCreated = yearCreated;
this.medium = medium;
}
public String getName() { return name; }
public int getYearCreated() { return yearCreated; }
public String getMedium() { return medium; }
@Override
public String toString() {
return name + "|" + yearCreated + "|" + medium;
}
}
private String name; // e.g. "Henri Matisse"
private List<Work> works = new ArrayList<>();
public Artist(String name) {
this.name = name;
}
public void addWork(Work work) {
this.works.add(work);
}
/**
* Writes the toString representation of each of this artist's works to the
* given writer. Also writes header lines containing the artist's name and
* number of works.
*
* If an IOException occurs, the message "IOException occurred" should be
* printed to System.out.
*
* @param writer writer to write this artist's works to
*/
public void saveWorksToFile(Writer writer) {
// write your code here
try {
BufferedWriter buffer = new BufferedWriter(writer);
buffer.write(this.name);
buffer.newLine();
buffer.write("works: " + this.works.size());
buffer.close();
}
catch (IOException e) {
System.out.println("IOException occurred");
}
}
}
I got these errors:
=> org.junit.ComparisonFailure: The expected value is: Vincent van Gogh[newline]works: 0[newline]-----[newline] expected:<...nt van Gogh => org.junit.ComparisonFailure: The expected value is: Vincent van Gogh[newline]works: 0[newline]-----[newline] expected:<...nt van Gogh => org.junit.ComparisonFailure: The expected value is: Vincent van Gogh[newline]works: 0[newline]-----[newline] expected:<...nt van Gogh => org.junit.ComparisonFailure: The expected value is: Claude Monet[newline]works: 2[newline]-----[newline]Bridge over a Pond of Water Lilies|1899|Oil on canvas[newline]Impression, Sunrise|1872|Oil on canvas expected:<...laude Monet => org.junit.ComparisonFailure: The expected value is: Claude Monet[newline]works: 2[newline]-----[newline]Bridge over a Pond of Water Lilies|1899|Oil on canvas[newline]Impression, Sunrise|1872|Oil on canvas expected:<...laude Monet => org.junit.ComparisonFailure: The expected value is: Henry Matisse[newline]works: 1[newline]-----[newline]Woman with a Hat|1905|Oil on canvas expected:<...nry Matisse => org.junit.ComparisonFailure: The expected value is: Henry Matisse[newline]works: 1[newline]-----[newline]Woman with a Hat|1905|Oil on canvas expected:<...nry Matisse => org.junit.ComparisonFailure: The expected value is: Henry Matisse[newline]works: 1[newline]-----[newline]Woman with a Hat|1905|Oil on canvas expected:<...nry Matisse => org.junit.ComparisonFailure: The expected value is: Claude Monet[newline]works: 2[newline]-----[newline]Bridge over a Pond of Water Lilies|1899|Oil on canvas[newline]Impression, Sunrise|1872|Oil on canvas expected:<...laude Monet
I have difficulties on making a new line, I tried both n and newLine() method but it doesn’t work. And also showing the number of works on the list should be correct. And for the loop, I think I should use for loop in this case to loop over the art works.
Any hints/ help would be great, thank you!
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Answer
Below is my code for method saveWorksToFile. It is the only part of the code in your question that I changed. (Notes after the code.)
public void saveWorksToFile(Writer writer) {
try {
writer.write(this.name);
writer.write(System.lineSeparator());
writer.write("works: " + this.works.size());
writer.write(System.lineSeparator());
writer.write("---");
writer.write(System.lineSeparator());
boolean first = true;
for (Work work : works) {
if (first) {
first = false;
}
else {
writer.write(System.lineSeparator());
}
writer.write(work.toString());
}
}
catch (IOException e) {
System.out.println("IOException occurred");
}
}
You are not meant to wrap the Writer parameter in a BufferedWriter. In general, for any method, you usually should not need to cast the parameter. Hence, in the above code, I use only the methods of class Writer. Also note that I do not close Writer since that should be left to the code that invoked method saveWorksToFile.
In order to write a line separator, I call method lineSeparator of class java.lang.System.
In order to print all the artist’s works one per line, I use a loop.
In order to ensure that the last entry in the artist’s list of works is written without a line separator, the first work is written without a line separator and every subsequent work is written with a preceding line separator.
Here is a method I wrote to test the above code. It uses class java.io.StringWriter which is a subclass of Writer since class Writer is abstract and has no public constructor. In general, you cannot instantiate an abstract class. You need to use a concrete subclass. I use StringWriter so as to be able to print its contents easily to the screen. You can use class java.io.FileWriter if you want to write to an actual file.
/**
* import java.io.StringWriter
*/
public static void main(String[] args) {
Artist artist = new Artist("Vincent van Gogh");
StringWriter sw = new StringWriter();
artist.saveWorksToFile(sw);
System.out.print(sw);
System.out.println();
artist = new Artist("Claude Monet");
Work work = new Work("Bridge over a Pond of Water Lilies", 1899, "Oil on canvas");
artist.addWork(work);
work = new Work("Impression, Sunrise", 1872, "Oil on canvas");
artist.addWork(work);
sw = new StringWriter();
artist.saveWorksToFile(sw);
System.out.print(sw);
System.out.println();
artist = new Artist("Henri Matisse");
work = new Work("Woman with a Hat", 1905, "Oil on canvas");
artist.addWork(work);
sw = new StringWriter();
artist.saveWorksToFile(sw);
System.out.print(sw);
}
This is the output I got when I ran the above main method.
Vincent van Gogh works: 0 --- Claude Monet works: 2 --- Bridge over a Pond of Water Lilies|1899|Oil on canvas Impression, Sunrise|1872|Oil on canvas Henry Matisse works: 1 --- Woman with a Hat|1905|Oil on canvas