KaiquanMah commited on
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Create 17b. Read numbers from a file

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Week 3: Objects, files and exceptions/17b. Read numbers from a file ADDED
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+ Numbers are stored in the file numbers.csv.
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+ One line contains several numbers separated by commas.
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+ The file could look like this:
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+ 1,2,1,2,3
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+ 4,3,2,3,2,4,2
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+ 1,2,3
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+
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+
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+ Write the method
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+
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+ ArrayList<Integer> allValues()
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+
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+ which reads the numbers from the file, and stores them in a list.
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+ Finally, the list is returned.
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+
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+
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+
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+ Example method call:
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+ public static void main(String[] args){
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+ ArrayList<Integer> list = allValues();
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+ System.out.println(list);
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+ }
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+
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+ Example output:
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+ [1, 2, 1, 2, 3, 4, 3, 2, 3, 2, 4, 2, 1, 2, 3]
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+
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+
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+
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+ ==================================
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+
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+
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+ import java.util.Random;
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+ import java.util.ArrayList;
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+ import java.io.FileNotFoundException;
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+ import java.util.Scanner;
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+ import java.io.File;*/
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+
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+
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+
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+ public class Test {
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+ public static void main(String[] args){
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+ final Random random = new Random();
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+
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+
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+ System.out.println("File:");
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+ for (String s : input) {
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+ System.out.println("" + s);
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+ }
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+
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+
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+ ArrayList<String> list = new ArrayList<>();
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+ Scanner scanner = new Scanner(System.in);
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+
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+
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+ System.out.println("Testing the file's numbers...");
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+
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+
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+ ArrayList<Integer> numbers = allValues();
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+ System.out.println("All values:");
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+ for (int value : numbers) {
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+ System.out.println(value);
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+ }
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+
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+ }
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+
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+ //ADD
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+ public static ArrayList<Integer> allValues() {
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+ ArrayList<Integer> list = new ArrayList<>();
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+
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+ try {
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+ Scanner reader = new Scanner(new File("numbers.csv"));
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+ // read each line
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+ while (reader.hasNextLine()) {
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+
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+ String line = reader.nextLine();
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+ // split line into array of Integer strings
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+ String[] values = line.split(",");
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+ for (String value : values) {
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+ list.add(Integer.valueOf(value));
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+ }
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+ }
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+ }
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+ catch (FileNotFoundException e) {
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+ System.out.println("Error: numbers.csv file not found");
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+ }
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+ return list;
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+ }
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+
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+
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+ }
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+
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+
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+
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+
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+
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+
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+
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+
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+ File:
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+ 431,668,669,425,27,491,241
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+ 751,718,167,454,665,251,958
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+ 218,887,235,954,948,947,763
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+ 122,306,137,719,905,921,349
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+ Testing the file's numbers...
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+ All values:
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+ 431
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+ 668
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+ 669
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+ 425
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+ 27
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+ 491
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+ 241
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+ 751
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+ 718
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+ 167
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+ 454
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+ 665
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+ 251
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+ 958
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+ 218
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+ 887
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+ 235
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+ 954
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+ 948
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+ 947
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+ 763
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+ 122
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+ 306
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+ 137
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+ 719
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+ 905
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+ 921
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+ 349
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+
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+
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+
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+
138
+