BAEL-255 - read file from Java

core-java-8/src/main/resources/fileTest.txt

@@ -0,0 +1 @@
+Hello World from fileTest.txt!!!

core-java-8/src/test/java/com/baeldung/file/FileOperationsTest.java

@@ -0,0 +1,78 @@
+package com.baeldung.file;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.net.URLConnection;
+
+import static org.hamcrest.CoreMatchers.containsString;
+
+public class FileOperationsTest {
+
+    @Test
+    public void givenFileName_whenUsingClassloader_thenFileData() throws IOException {
+        String expectedData = "Hello World from fileTest.txt!!!";
+
+        ClassLoader classLoader = getClass().getClassLoader();
+        InputStream inputStream = classLoader.getResourceAsStream("fileTest.txt");
+        String data = readFromInputStream(inputStream);
+
+        Assert.assertThat(data, containsString(expectedData));
+}
+
+    @Test
+    public void givenFileNameAsAbsolutePath_whenUsingClasspath_thenFileData() throws IOException {
+        String expectedData = "Hello World from fileTest.txt!!!";
+
+        Class clazz = FileOperationsTest.class;
+        InputStream inputStream = clazz.getResourceAsStream("/fileTest.txt");
+        String data = readFromInputStream(inputStream);
+
+        Assert.assertThat(data, containsString(expectedData));
+    }
+
+    @Test
+    public void givenURLName_whenUsingURL_thenFileData() throws IOException {
+        String expectedData = "Baeldung";
+
+        URL urlObject = new URL("http://www.baeldung.com/");
+        URLConnection urlConnection = urlObject.openConnection();
+
+        InputStream inputStream = urlConnection.getInputStream();
+        String data = readFromInputStream(inputStream);
+
+        Assert.assertThat(data, containsString(expectedData));
+    }
+
+    @Test
+    public void givenFileName_whenUsingJarFile_thenFileData() throws IOException {
+        String expectedData = "BSD License";
+
+        Class clazz = Matchers.class;
+        InputStream inputStream = clazz.getResourceAsStream("/LICENSE.txt");
+        String data = readFromInputStream(inputStream);
+
+        Assert.assertThat(data, containsString(expectedData));
+    }
+
+    private String readFromInputStream(InputStream inputStream) throws IOException {
+        InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
+        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
+        StringBuilder resultStringBuilder = new StringBuilder();
+        String line;
+        while ((line = bufferedReader.readLine()) != null) {
+            resultStringBuilder.append(line);
+            resultStringBuilder.append("\n");
+        }
+        bufferedReader.close();
+        inputStreamReader.close();
+        inputStream.close();
+        return resultStringBuilder.toString();
+    }
+}