Merge pull request #317 from dasvipin5585/master

Java - Try with resources code commit

core-java-8/src/test/java/org/baeldung/java8/JavaTryWithResourcesTest.java

@@ -0,0 +1,94 @@
+package org.baeldung.java8;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.Date;
+import java.util.Scanner;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class JavaTryWithResourcesTest {
+
+    private static final String TEST_STRING_HELLO_WORLD = "Hello World";
+    private Date resource1Date, resource2Date;
+
+    /*
+     * Example for using Try_with_resources
+     */
+    @Test
+    public void whenWritingToStringWriter_thenCorrectlyWritten() {
+
+        StringWriter sw = new StringWriter();
+        try (PrintWriter pw = new PrintWriter(sw, true)) {
+            pw.print(TEST_STRING_HELLO_WORLD);
+        }
+
+        Assert.assertEquals(sw.getBuffer().toString(), TEST_STRING_HELLO_WORLD);
+    }
+
+    /*
+     * Example for using multiple resources
+     */
+    @Test
+    public void givenStringToScanner_whenWritingToStringWriter_thenCorrectlyWritten() {
+
+        StringWriter sw = new StringWriter();
+        try (Scanner sc = new Scanner(TEST_STRING_HELLO_WORLD); PrintWriter pw = new PrintWriter(sw, true)) {
+            while (sc.hasNext()) {
+                pw.print(sc.nextLine());
+            }
+        }
+
+        Assert.assertEquals(sw.getBuffer().toString(), TEST_STRING_HELLO_WORLD);
+    }
+
+    /*
+     * Example to show order in which the resources are closed
+     */
+    @Test
+    public void whenFirstAutoClosableResourceIsinitializedFirst_thenFirstAutoClosableResourceIsReleasedFirst() throws Exception {
+
+        try (AutoCloseableResourcesFirst af = new AutoCloseableResourcesFirst(); AutoCloseableResourcesSecond as = new AutoCloseableResourcesSecond()) {
+            af.doSomething();
+            as.doSomething();
+        }
+        Assert.assertTrue(resource1Date.after(resource2Date));
+    }
+
+    class AutoCloseableResourcesFirst implements AutoCloseable {
+
+        public AutoCloseableResourcesFirst() {
+            System.out.println("Constructor -> AutoCloseableResources_First");
+        }
+
+        public void doSomething() {
+            System.out.println("Something -> AutoCloseableResources_First");
+        }
+
+        @Override
+        public void close() throws Exception {
+            System.out.println("Closed AutoCloseableResources_First");
+            resource1Date = new Date();
+
+        }
+    }
+
+    class AutoCloseableResourcesSecond implements AutoCloseable {
+
+        public AutoCloseableResourcesSecond() {
+            System.out.println("Constructor -> AutoCloseableResources_Second");
+        }
+
+        public void doSomething() {
+            System.out.println("Something -> AutoCloseableResources_Second");
+        }
+
+        @Override
+        public void close() throws Exception {
+            System.out.println("Closed AutoCloseableResources_Second");
+            resource2Date = new Date();
+            Thread.sleep(10000);
+        }
+    }
+}