[rm-linebreaks-inFile] How to Remove Line Breaks From a File in Java (#14917)

core-java-modules/core-java-io-5/src/test/java/com/baeldung/rmlinebreaks/RemoveLinebreaksUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.rmlinebreaks;
+
+import org.junit.jupiter.api.Test;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+public class RemoveLinebreaksUnitTest {
+
+    private Path file1Path() throws Exception {
+        return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-1.txt").toURI());
+    }
+
+    private Path file2Path() throws Exception {
+        return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-2.txt").toURI());
+    }
+
+    @Test
+    void whenRemovingLineSeparatorFromFile1_thenGetTheExpectedResult() throws Exception {
+        String content = Files.readString(file1Path(), StandardCharsets.UTF_8);
+
+        String result = content.replace(System.getProperty("line.separator"), "");
+        assertEquals("A, B, C, D, E, F", result);
+    }
+
+    @Test
+    void whenRemovingLineSeparatorFromFile2_thenNotGetTheExpectedResult() throws Exception {
+        String content = Files.readString(file2Path(), StandardCharsets.UTF_8);
+
+        String result = content.replace(System.getProperty("line.separator"), "");
+        assertNotEquals("A, B, C, D, E, F", result); // <-- NOT equals assertion!
+    }
+
+    @Test
+    void whenRemovingAllLinebreaks_thenGetTheExpectedResult() throws Exception {
+        String content1 = Files.readString(file1Path(), StandardCharsets.UTF_8);
+
+        // file contains CRLF
+        String content2 = Files.readString(file2Path(), StandardCharsets.UTF_8);
+
+        String result1 = content1.replace("\r", "").replace("\n", "");
+        String result2 = content2.replace("\r", "").replace("\n", "");
+
+        assertEquals("A, B, C, D, E, F", result1);
+        assertEquals("A, B, C, D, E, F", result2);
+
+        String resultReplaceAll = content2.replaceAll("[\\n\\r]", "");
+        assertEquals("A, B, C, D, E, F", resultReplaceAll);
+
+    }
+
+    @Test
+    void whenUsingReadAllLinesAndJoin_thenGetExpectedResult() throws Exception {
+        List<String> lines1 = Files.readAllLines(file1Path(), StandardCharsets.UTF_8);
+
+        // file contains CRLF
+        List<String> lines2 = Files.readAllLines(file2Path(), StandardCharsets.UTF_8);
+
+        String result1 = String.join("", lines1);
+        String result2 = String.join("", lines2);
+
+        assertEquals("A, B, C, D, E, F", result1);
+        assertEquals("A, B, C, D, E, F", result2);
+    }
+
+}

core-java-modules/core-java-io-5/src/test/resources/multiple-line-1.txt

@@ -0,0 +1,6 @@
+A,
+ B,
+ C,
+ D,
+ E,
+ F

core-java-modules/core-java-io-5/src/test/resources/multiple-line-2.txt

@@ -0,0 +1,4 @@
+A,
 B,
+ C,
+ D,
 E,
+ F