BAEL-2542 Creating a Jar - example code

core-java/src/main/java/com/baeldung/jar/Dimensioner.java

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+package com.baeldung.jar;
+
+import java.io.BufferedReader;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+
+public class Dimensioner {
+
+    public List<Rectangle> loadFromFile(String dimensionFile) throws FileNotFoundException, IOException {
+        List<Rectangle> rectangles = new ArrayList<Rectangle>();
+        try (BufferedReader br = new BufferedReader(new InputStreamReader(Dimensioner.class.getResourceAsStream(dimensionFile)))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                String[] dimensions = line.split(",");
+                if (dimensions.length == 2) {
+                    Rectangle rectangle = new Rectangle(Integer.valueOf(dimensions[0]), Integer.valueOf(dimensions[1]));
+                    rectangles.add(rectangle);
+                }
+            }
+        }
+        return rectangles;
+    }
+
+}

core-java/src/main/java/com/baeldung/jar/JarExample.java

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+package com.baeldung.jar;
+
+import java.io.IOException;
+import java.util.List;
+
+public class JarExample {
+    private static final String DIMENSION_FILE = "/dimensions.txt";
+
+    public static void main(String[] args) {
+        String environment = System.getProperty("environment");
+        if (environment != null && environment.equalsIgnoreCase("prod")) {
+            Dimensioner dimensioner = new Dimensioner();
+            try {
+                List<Rectangle> rectangles = dimensioner.loadFromFile(DIMENSION_FILE);
+                rectangles.forEach(rectangle -> {
+                    rectangle.printArea();
+                    rectangle.printPerimeter();
+                });
+            } catch (IOException e) {
+                System.err.println("Exception loading dimensions");
+            }
+        } else if (args.length > 0) {
+            int length = Integer.valueOf(args[0]);
+            int width = (args.length > 1) ? Integer.valueOf(args[1]) : Integer.valueOf(args[0]);
+            Rectangle rectangle = new Rectangle(length, width);
+            rectangle.printArea();
+            rectangle.printPerimeter();
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/jar/Rectangle.java

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+package com.baeldung.jar;
+
+public class Rectangle {
+    private int length;
+    private int width;
+
+    public Rectangle(int length, int width) {
+        this.length = length;
+        this.width = width;
+    }
+
+    public int area() {
+        return length * width;
+    }
+
+    public int perimeter() {
+        return (length * 2) + (width * 2);
+    }
+
+    public void printArea() {
+        System.out.println("Area: " + area());
+    }
+
+    public void printPerimeter() {
+        System.out.println("Perimeter: " + perimeter());
+    }
+
+    public int getLength() {
+        return length;
+    }
+
+    public void setLength(int length) {
+        this.length = length;
+    }
+
+    public int getWidth() {
+        return width;
+    }
+
+    public void setWidth(int width) {
+        this.width = width;
+    }
+
+}

core-java/src/main/resources/META-INF/example_manifest.txt

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+Main-Class: com.baeldung.jar.JarExample

core-java/src/main/resources/files/dimensions.txt

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+12,16
+24,6
+7,19