Develop Reference

How to print contents of a text to console as objects

Let's say I have theese words in a text file
Dictionary.txt
artificial
intelligence
abbreviation
hybrid
hysteresis
illuminance
identity
inaccuracy
impedance
impenetrable
imperfection
impossible
independent
How can I make each word a different object and print them on the console?

You can simple use Scanner.nextLine(); function.
Here is the following code which can help
also import the libraries
import java.util.Scanner;
import java.io.File;
import java.util.Arrays;
Use following code:-
String []words = new String[1];
try{
File file = new File("/path/to/Dictionary.txt");
Scanner scan = new Scanner(file);
int i=0;
while(scan.hasNextLine()){
words[i]=scan.nextLine();
i++;
words = Arrays.copyOf(words,words.legnth+1); // Increasing legnth of array with 1
}
}
catch(Exception e){
System.out.println(e);
}
You must go and research on Scanner class

This is a very simple solution using Files:
package org.kodejava.io;
import java.net.URI;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
import java.util.Objects;
public class ReadFileAsListDemo {
public static void main(String[] args) {
ReadFileAsListDemo demo = new ReadFileAsListDemo();
demo.readFileAsList();
}
private void readFileAsList() {
String fileName = "Dictionary.txt";
try {
URI uri = Objects.requireNonNull(this.getClass().getResource(fileName)).toURI();
List<String> lines = Files.readAllLines(Paths.get(uri),
Charset.defaultCharset());
for (String line : lines) {
System.out.println(line);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
Source: https://kodejava.org/how-do-i-read-all-lines-from-a-file/
This is another neat solution using buffered reader:
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 * BufferedReader and Scanner can be used to read
line by line from any File or
 * console in Java.
 * This Java program
demonstrate line by line reading using BufferedReader in Java
 *
 * #author Javin Paul
 */
public class BufferedReaderExample {
public static void main(String args[]) {
//reading file line by line in Java using BufferedReader
FileInputStream fis = null;
BufferedReader reader = null;
try {
fis = new FileInputStream("C:/sample.txt");
reader = new BufferedReader(new InputStreamReader(fis));
System.out.println("Reading
File line by line using BufferedReader");
String line = reader.readLine();
while(line != null){
System.out.println(line);
line = reader.readLine();
}
} catch (FileNotFoundException ex) {
Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
reader.close();
fis.close();
} catch (IOException ex) {
Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
Source: https://javarevisited.blogspot.com/2012/07/read-file-line-by-line-java-example-scanner.html#axzz7lrQcYlyy

These are all good answers. The OP didn't state what release of Java they require, but in modern Java I'd just use:
import java.nio.file.*;
public class x {
public static void main(String[] args) throws java.io.IOException {
Files.lines(Path.of("/path/to/Dictionary.txt")).forEach(System.out::println);
}
}

Only catch certain word lengths

If I got a .txt file named words.txt and I want to catch the words to input them into an arraylist how do I do that. I know buffered reader exists but I dont quite get how to use it. All words are seperated by a space or an enter key. It has to then for example filter out words that are not 4 characters long and place the 4 long words in an arraylist to use later.
For example I got this txt file :
one > gets ignored
two > gets ignored
three > gets ignored
four > caught and put into for example arraylist
five > 4 long so gets caught and put into arraylist
six > ignored
seven > ignored
eight > ignored
nine > caught because its 4 char long
ten > ignored

You can do it using streams and NIO.2
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class Main {
public static void main(String[] args) {
Path path = Paths.get("words.txt");
try (Stream<String> lines = Files.lines(path)) {
List<String> list = lines.filter(word -> word.length() == 4)
.collect(Collectors.toList());
System.out.println(list);
}
catch (IOException xIo) {
xIo.printStackTrace();
}
}
}
Here is my words.txt file:
one
two
three
four
five
six
seven
eight
nine
ten
And running the above code, using the above file, prints the following:
[four, five, nine]
Alternatively, you can use a Scanner
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Path source = Paths.get("words.txt");
try (Scanner scanner = new Scanner(source)) {
List<String> list = new ArrayList<>();
while (scanner.hasNextLine()) {
String word = scanner.nextLine();
if (word.length() == 4) {
list.add(word);
}
}
System.out.println(list);
}
catch (IOException xIo) {
xIo.printStackTrace();
}
}
}
Note that both the above versions of class Main use try-with-resources.
Yet another way is to use class java.io.BufferedReader (since you mentioned it in your question).
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class Main {
public static void main(String[] args) {
File f = new File("words.txt");
try (FileReader fr = new FileReader(f);
BufferedReader br = new BufferedReader(fr)) {
List<String> list = new ArrayList<>();
String line = br.readLine();
while (line != null) {
if (line.length() == 4) {
list.add(line);
}
line = br.readLine();
}
System.out.println(list);
}
catch (IOException xIo) {
xIo.printStackTrace();
}
}
}

save single string to array separate by multi space in file text java

I'm a java beginner and I'm doing a small project about dictionary, now I want to save word and translate mean in file, because my native language often have space like chicken will be con gà so, I must use other way, not by space, but I really don't know how to do that, a word and it translation in one line, separate by "tab", mean multi space like chicken con gà now I want to get 2 words and store it in my array of Words which I created before, so I want to do something like
w1=word1inline;
w2=word2inline;
Word(word1inline,word2inline);(this is a member of array);
please help me, thanks a lot, I just know how to read line from file text, and use split to get word but I am not sure how to read by multi space.
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
public class docfile {
public static void main(String[] args)
{
String readLine;
ArrayList<String>str=new ArrayList<>(String);
try {
File file = new File("text.txt");
BufferedReader b = new BufferedReader(new FileReader(file));
while ((readLine = b.readLine()) != null) {
str.add()=readLine.split(" ");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

If you stick to using tabs as a separator, this should work:
package Application;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
public class Application {
public static void main(String[] args) {
String line;
ArrayList<String> str = new ArrayList<>();
try {
File file = new File("text.txt");
BufferedReader b = new BufferedReader(new FileReader(file));
while ((line = b.readLine()) != null) {
for (String s : line.split("\t")) {
str.add(s);
}
}
str.forEach(System.out::println);
} catch (IOException e) {
e.printStackTrace();
}
}
}

Why not just use a properties file?
dict.properties:
chicken=con gá
Dict.java:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Properties;
public class Dict {
public static void main(String[] args) throws IOException {
Properties dict = new Properties();
dict.load(Files.newBufferedReader(Paths.get("dict.properties")));
System.out.println(dict.getProperty("chicken"));
}
}
Output:
con gá

If your line is like this chicken con gà you can use indexof() method to find the first space in the string.
Then you can substring each word by using substring() method.
readLine = b.readLine();
ArrayList<String>str=new ArrayList<>();
int i = readLine.indexOf(' ');
String firstWord = readLine.substring(0, i);
String secondWord = readLine.substring(i+1, readLine.length());
str.add(firstWord);
str.add(secondWord);

Importing API into my java program

I am new to WebAPIs, and I was asked to acquire the longitude and latitude of a specific location with the help of a certain website's APIs. (website deleted), and I was provided with an asset key as well.
I think my question here is, how do I import this API into my program in Java?

Here's a simple example of Assets query from that page using the provided demo key:
EXAMPLE QUERY
https://api.nasa.gov/planetary/earth/assets?lon=100.75&lat=1.5&begin=2014-02-01&api_key=DEMO_KEY
[this is in Java 6, modify to suit your Java version]
import java.io.BufferedReader;
import java.lang.StringBuilder;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.net.URL;
import java.net.URLConnection;
import java.io.IOException;
public class NasaRestAPIExample {
public static void main(String[] args) throws IOException {
String query = "lon=100.75&lat=1.5&begin=2014-02-01&api_key=DEMO_KEY";
URLConnection connection = new URL("https://api.nasa.gov/planetary/earth/assets?" + query).openConnection();
connection.connect();
BufferedReader r = new BufferedReader(new InputStreamReader(connection.getInputStream(), Charset.forName("UTF-8")));
StringBuilder sb = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
sb.append(line);
}
System.out.println(sb.toString());
}
}
output:
{"count": 61, "results": [{"date": "2014-02-04T03:30:01", "id": "LC8_L1T_TOA/LC81270592014035LGN00"}, ...

Java arraylist to array, array to string error

I have to read data from text.txt file, but I have strange error, my output is: [Ljava.lang.String;#5f0a94c5.
The contents of text.txt file:
test::test.1::test.2
test2::test2.1::test2.2
test3::test3.1::test3.2
The code:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
public class test {
public static void main(String[] args){
ArrayList<String> data = new ArrayList<String>();
try (BufferedReader br = new BufferedReader(new FileReader("test.txt"))) {
String CurrLine;
while((CurrLine = br.readLine()) != null) {
data.add(CurrLine);
}
String[] dataArray = new String[data.size()];
data.toArray(dataArray);
Arrays.toString(dataArray);
System.out.println(dataArray);
} catch(FileNotFoundException ex) {
System.out.println("FNFE");
} catch(IOException ex) {
System.out.println("IOE");
}
}
}

You need to use:
System.out.println(Arrays.toString(dataArray));
In your code, Arrays.toString(dataArray); does nothing as you don't do anything with its returned value.
BTW, as #ZouZou pointed out, you can also print your ArrayList directly:
System.out.println(data);

Your code : System.out.println(dataArray); will output the hashcode value for the object dataArray. Any array in Java does not override equals() method. As a result, when you try to print the value of the array object, java.lang.Object.equals() method is invoked which prints the hashcode of the object .
Instead try using System.out.println(Arrays.toString(dataArray));