[BAEL-19088] - Move articles out of core-java-io part 3

core-java-modules/core-java-io-apis/src/main/java/com/baeldung/scanner/HasNextVsHasNextLineDemo.java

@@ -0,0 +1,96 @@
+package com.baeldung.scanner;
+
+import lombok.extern.log4j.Log4j;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.PropertyConfigurator;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+import java.util.Scanner;
+
+@Log4j
+public class HasNextVsHasNextLineDemo {
+    private static final String LINE = "----------------------------";
+    private static final String END_LINE = "--------OUTPUT--END---------\n";
+
+
+    private static final String INPUT = new StringBuilder()
+        .append("magic\tproject\n")
+        .append("     database: oracle\n")
+        .append("dependencies:\n")
+        .append("spring:foo:bar\n")
+        .append("\n").toString();
+
+    private static void hasNextBasic() {
+        printHeader("hasNext() Basic");
+        Scanner scanner = new Scanner(INPUT);
+        while (scanner.hasNext()) {
+            log.info(scanner.next());
+        }
+        log.info(END_LINE);
+        scanner.close();
+    }
+
+    private static void hasNextWithDelimiter() {
+        printHeader("hasNext() with delimiter");
+        Scanner scanner = new Scanner(INPUT);
+        while (scanner.hasNext()) {
+            String token = scanner.next();
+            if ("dependencies:".equals(token)) {
+                scanner.useDelimiter(":");
+            }
+            log.info(token);
+        }
+        log.info(END_LINE);
+        scanner.close();
+    }
+
+    private static void hasNextWithDelimiterFixed() {
+        printHeader("hasNext() with delimiter FIX");
+        Scanner scanner = new Scanner(INPUT);
+        while (scanner.hasNext()) {
+            String token = scanner.next();
+            if ("dependencies:".equals(token)) {
+                scanner.useDelimiter(":|\\s+");
+            }
+            log.info(token);
+        }
+        log.info(END_LINE);
+        scanner.close();
+    }
+
+    private static void addLineNumber() {
+        printHeader("add line number by hasNextLine() ");
+        Scanner scanner = new Scanner(INPUT);
+        int i = 0;
+        while (scanner.hasNextLine()) {
+            log.info(String.format("%d|%s", ++i, scanner.nextLine()));
+        }
+        log.info(END_LINE);
+        scanner.close();
+    }
+
+    private static void printHeader(String title) {
+        log.info(LINE);
+        log.info(title);
+        log.info(LINE);
+    }
+
+    public static void main(String[] args) throws IOException {
+        setLogger();
+        hasNextBasic();
+        hasNextWithDelimiter();
+        hasNextWithDelimiterFixed();
+        addLineNumber();
+    }
+
+    //overwrite the logger config
+    private static void setLogger() throws IOException {
+        InputStream is = HasNextVsHasNextLineDemo.class.getResourceAsStream("/scanner/log4j.properties");
+        Properties props = new Properties();
+        props.load(is);
+        LogManager.resetConfiguration();
+        PropertyConfigurator.configure(props);
+    }
+}

core-java-modules/core-java-io-apis/src/main/resources/scanner/log4j.properties

@@ -0,0 +1,4 @@
+log4j.rootLogger=INFO, A1
+log4j.appender.A1=org.apache.log4j.ConsoleAppender
+log4j.appender.A1.layout=org.apache.log4j.PatternLayout
+log4j.appender.A1.layout.ConversionPattern=[DEMO]%m%n

core-java-modules/core-java-io-apis/src/test/java/com/baeldung/scannernextline/ScannerNextLineUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.scannernextline;
+
+import org.junit.Test;
+
+import java.util.NoSuchElementException;
+import java.util.Scanner;
+
+import static org.junit.Assert.assertEquals;
+
+public class ScannerNextLineUnitTest {
+
+    @Test
+    public void whenReadingLines_thenCorrect() {
+        String input = "Scanner\nTest\n";
+        try (Scanner scanner = new Scanner(input)) {
+            assertEquals("Scanner", scanner.nextLine());
+            assertEquals("Test", scanner.nextLine());
+        }
+    }
+
+    @Test
+    public void whenReadingPartialLines_thenCorrect() {
+        String input = "Scanner\n";
+        try (Scanner scanner = new Scanner(input)) {
+            scanner.useDelimiter("");
+            scanner.next();
+            assertEquals("canner", scanner.nextLine());
+        }
+    }
+
+    @Test(expected = NoSuchElementException.class)
+    public void givenNoNewLine_whenReadingNextLine_thenThrowNoSuchElementException() {
+        try (Scanner scanner = new Scanner("")) {
+            String result = scanner.nextLine();
+        }
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void givenScannerIsClosed_whenReadingNextLine_thenThrowIllegalStateException() {
+        Scanner scanner = new Scanner("");
+        scanner.close();
+        String result = scanner.nextLine();
+    }
+}