lesson 5

AppData.java

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+package ru.gb.lesson5;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+public class AppData implements Serializable {
+    private final String[] headers;
+    private final int[][] data;
+
+    public AppData(String[] headers, int[][] data) {
+        this.headers = headers;
+        this.data = data;
+    }
+
+    public AppData(String appData) {
+        String[] tokens = appData.split("[\\r\n]+");
+        this.headers = tokens[0].split(";");
+        int[][] data = new int[headers.length - 1][headers.length];
+        for (int i = 1; i < tokens.length; i++) {
+            String[] values = tokens[i].split(";");
+            for (int j = 0; j < values.length; j++) {
+                data[i - 1][j] = Integer.parseInt(values[j]);
+            }
+        }
+        this.data = data;
+    }
+    public void writeToFile(String path) {
+        File file = new File(path);
+        writeToFile(file);
+    }
+    public void writeToFile(File file) {
+        try (OutputStreamWriter outputStream = new OutputStreamWriter(
+                new FileOutputStream(file), StandardCharsets.UTF_8)) {
+            outputStream.write(this.toString());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private String headersToString() {
+        StringBuilder result = new StringBuilder();
+        for (String header : headers) {
+            result.append(header).append(";");
+        }
+        return  result.append("\n").toString().replaceFirst(";$", "");
+    }
+   private String dataToString() {
+        StringBuilder result = new StringBuilder();
+        for (int[] values : data) {
+            StringBuilder resultBuilder = new StringBuilder();
+            for (int value : values) {
+                resultBuilder.append(value).append(";");
+            }
+            resultBuilder.append("\n");
+            result.append(resultBuilder.toString().replaceFirst(";$", ""));
+        }
+        return result.append("\n").toString();
+   }
+
+    @Override
+    public String toString() {
+        return headersToString() + dataToString();
+    }
+
+    public static AppData readFromFile(String path) {
+        File file = new File(path);
+        return readFromFile(file);
+    }
+    public static AppData readFromFile(File file) {
+        StringBuilder result = new StringBuilder();
+        try (InputStreamReader inputStream = new InputStreamReader(
+                new FileInputStream(file), StandardCharsets.UTF_8)) {
+            int count;
+            while ((count = inputStream.read()) != -1) {
+                result.append((char) count);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return new AppData(result.toString());
+    }
+}

Main.java

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+package ru.gb.lesson5;
+
+public class Main {
+    public static final String PATH = "src/main/java/ru/gb/lesson5/demo.csv";
+
+    public static void main(String[] args) {
+        String[] headers = {"Value 1", "Value 2", "Value 3"};
+        int[][] data = { {100, 200, 123}, {300, 400, 500}};
+
+        AppData appData = new AppData(headers, data);
+
+        appData.writeToFile(PATH);
+        AppData receivedAppData = AppData.readFromFile(PATH);
+        System.out.println(receivedAppData);
+
+        }
+    }

demo.csv

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+Value 1;Value 2;Value 3
+100;200;123
+300;400;500