Primary Commit

core-java-modules/core-java-streams-5/pom.xml

@@ -43,6 +43,12 @@
             <artifactId>vavr</artifactId>
             <version>${vavr.version}</version>
         </dependency>
+		<dependency>
+			<groupId>com.codepoetics</groupId>
+			<artifactId>protonpack</artifactId>
+			<version>1.16</version>
+		</dependency>
+
     </dependencies>
 
     <build>

core-java-modules/core-java-streams-5/src/test/java/com/baeldung/streams/firstmatchingelement/FirstMatchingElementUnitTest.java

@@ -0,0 +1,104 @@
+package com.baeldung.streams.firstmatchingelement;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.Optional;
+import java.util.OptionalInt;
+import java.util.stream.IntStream;
+
+import org.assertj.core.util.Lists;
+import org.junit.Test;
+
+import com.codepoetics.protonpack.StreamUtils;
+
+public class FirstMatchingElementUnitTest {
+
+    @Test
+    public void testWithForLoop() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE);
+        int index = -1;
+        for (int i = 0; i < dataList.size(); i++) {
+            if (dataList.get(i) instanceof Boolean) {
+                index = i;
+            }
+        }
+        assertEquals(2, index);
+    }
+
+    @Test
+    public void testWithIndexOf() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE);
+        Optional<Object> booleanData = dataList.stream()
+            .filter(data -> data instanceof Boolean)
+            .findFirst();
+        int index = booleanData.isPresent() ? dataList.indexOf(booleanData.get()) : -1;
+        assertEquals(2, index);
+    }
+
+    @Test
+    public void testWithIterator() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE);
+        int index = -1;
+        Iterator<Object> iterator = dataList.iterator();
+        while (iterator.hasNext()) {
+            Object data = iterator.next();
+            if (data instanceof Boolean) {
+                index = dataList.indexOf(data);
+                break;
+            }
+        }
+        assertEquals(2, index);
+    }
+
+    @Test
+    public void testWithListIterator() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE);
+        int index = -1;
+        ListIterator<Object> listIterator = dataList.listIterator();
+        while (listIterator.hasNext()) {
+            if (listIterator.next() instanceof Boolean) {
+                index = listIterator.previousIndex();
+                break;
+            }
+        }
+        assertEquals(2, index);
+    }
+
+    @Test
+    public void testWithTakeAWhile() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE, 2, 3);
+        OptionalInt booleanIndex = dataList.stream()
+            .takeWhile(data -> !(data instanceof Boolean))
+            .mapToInt(dataList::indexOf)
+            .max();
+
+        if (booleanIndex.isPresent() && dataList.get(booleanIndex.getAsInt()) instanceof Boolean) {
+            assertEquals(2, booleanIndex.getAsInt());
+        }
+    }
+
+    @Test
+    public void testWithIntStream() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE);
+        int index = IntStream.of(0, dataList.size() - 1)
+            .filter(streamIndex -> dataList.get(streamIndex) instanceof Boolean)
+            .findFirst()
+            .orElse(-1);
+        assertEquals(2, index);
+    }
+
+    @Test
+    public void testWithZipWithIndex() {
+        List<Object> dataList = Lists.newArrayList("String", 1, Boolean.TRUE, 2, 3);
+        int index = StreamUtils.zipWithIndex(dataList.stream())
+            .filter(i -> i.getValue() instanceof Boolean)
+            .mapToInt(i -> Long.valueOf(i.getIndex())
+                .intValue())
+            .findFirst()
+            .orElse(-1);
+        assertEquals(2, index);
+    }
+}