BAEL-7839: Converting Image to BufferedImage in Java (#16403)

* BAEL-7765: How to fix JsonParseException: Unexpected character (code 115) when parsing unquoted JSON in Jackson

* BAEL-7839: Converting Image to BufferedImage in Java

image-processing/src/main/java/com/baeldung/imageprocessing/imagetobufferedimage/ImageToBufferedImage.java

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+package com.baeldung.imageprocessing.imagetobufferedimage;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+public class ImageToBufferedImage {
+
+    // Method 1: Using BufferedImage Constructor
+    public BufferedImage convertUsingConstructor(Image image) throws IllegalArgumentException {
+        int width = image.getWidth(null);
+        int height = image.getHeight(null);
+        if (width <= 0 || height <= 0) {
+            throw new IllegalArgumentException("Image dimensions are invalid");
+        }
+        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
+        bufferedImage.getGraphics().drawImage(image, 0, 0, null);
+        return bufferedImage;
+    }
+
+    // Method 2: Casting Image to BufferedImage
+    public BufferedImage convertUsingCasting(Image image) throws ClassCastException {
+        if (image instanceof BufferedImage) {
+            return (BufferedImage) image;
+        } else {
+            throw new ClassCastException("Image type is not compatible with BufferedImage");
+        }
+    }
+
+    // Method 3: Using ImageIO Class
+    public BufferedImage convertUsingImageIO(String filePath) throws IOException {
+        try {
+            File file = new File(filePath);
+            return ImageIO.read(file);
+        } catch (Exception e) {
+            throw new IOException("Error reading image file: " + e.getMessage());
+        }
+    }
+}

image-processing/src/test/java/com/baeldung/image/resize/imagetobufferedimage/ImageToBufferedImageUnitTest.java

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+package com.baeldung.image.resize.imagetobufferedimage;
+
+import com.baeldung.imageprocessing.imagetobufferedimage.ImageToBufferedImage;
+import org.junit.Test;
+
+import javax.imageio.ImageIO;
+import javax.swing.*;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+public class ImageToBufferedImageUnitTest {
+    Image image = ImageIO.read(new File("src/main/resources/images/sampleImage.jpg"));
+
+    public ImageToBufferedImageUnitTest() throws IOException {
+    }
+
+    @Test
+    public void whenConvertUsingConstructorWithValidDimensions_thenImageGeneratedWithoutError() {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        BufferedImage bufferedImage = converter.convertUsingConstructor(image);
+        assertNotNull(bufferedImage);
+        assertEquals(image.getWidth(null), bufferedImage.getWidth());
+        assertEquals(image.getHeight(null), bufferedImage.getHeight());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void whenConvertUsingConstructorWithInvalidDimensions_thenImageGeneratedWithError() {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        converter.convertUsingConstructor(new BufferedImage(-100, -100, BufferedImage.TYPE_INT_ARGB));
+    }
+
+    @Test
+    public void whenConvertUsingCastingWithCompatibleImageType_thenImageGeneratedWithoutError() {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        BufferedImage bufferedImage = converter.convertUsingCasting(image);
+        assertNotNull(bufferedImage);
+        assertEquals(image.getWidth(null), bufferedImage.getWidth());
+        assertEquals(image.getHeight(null), bufferedImage.getHeight());
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void whenConvertUsingCastingWithIncompatibleImageType_thenImageGeneratedWithError() {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        // PNG format is not directly supported by BufferedImage
+        Image image = new ImageIcon("src/main/resources/images/baeldung.png").getImage();
+        converter.convertUsingCasting(image);
+    }
+
+    @Test
+    public void whenConvertUsingImageIOWithValidFile_thenImageGeneratedWithoutError() throws IOException {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        BufferedImage bufferedImage = converter.convertUsingImageIO("src/main/resources/images/sampleImage.jpg");
+        assertNotNull(bufferedImage);
+        assertEquals(image.getWidth(null), bufferedImage.getWidth());
+        assertEquals(image.getHeight(null), bufferedImage.getHeight());
+    }
+
+    @Test(expected = IOException.class)
+    public void whenConvertUsingImageIOWithInvalidFile_thenImageGeneratedWithError() throws IOException {
+        ImageToBufferedImage converter = new ImageToBufferedImage();
+        converter.convertUsingImageIO("invalid_file.jpg");
+    }
+}
+