Add Minutes to a String Time in Java (#14767)

core-java-modules/core-java-8-datetime-2/src/test/java/com/baeldung/stringtime/AddMinuteStringTimeUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.stringtime;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalTime;
+import java.util.Calendar;
+import java.util.Date;
+import org.junit.jupiter.api.Test;
+
+public class AddMinuteStringTimeUnitTest {
+
+    @Test
+    public void givenTimeStringUsingSimpleDateFormat_whenIncrementedWith10Minutes_thenResultShouldBeCorrect() throws ParseException {
+        String timeString = "23:45";
+        SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm");
+        Date date = timeFormat.parse(timeString);
+
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(date);
+        cal.add(Calendar.MINUTE, 10);
+        String result = timeFormat.format(cal.getTime());
+        assertEquals("23:55", result);
+
+    }
+
+    @Test
+    public void givenTimeStringUsingLocalTime_whenIncrementedWith10Minutes_thenResultShouldBeCorrect() {
+        String timeString = "23:45";
+        LocalTime time = LocalTime.parse(timeString);
+        LocalTime newTime = time.plusMinutes(10);
+        String result = newTime.toString();
+        assertEquals("23:55", result);
+    }
+
+}