HW_done (without task 10)

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task1.java

@@ -2,6 +2,9 @@
 
 public class Task1 {
     public static String makeTags(String tag, String text) {
-        return "";
+        StringBuilder tagText = new StringBuilder();
+        tagText.append("<").append(tag).append(">").append(text).append("</").append(tag).append(">");
+        return tagText.toString();
+
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task10.java

@@ -1,7 +1,20 @@
 package school.lemon.changerequest.java.introduction.hw2;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 public class Task10 {
     public static String trim(String text) {
+        if (text == null) {
+            return null;
+        }
+        String regExp = "(((?<=[\\t]\\s)[a-z,A-Z]+.*[^\\s\\t]+)|([A-Z]).*[^\\t\\s])";
+        Pattern pattern = Pattern.compile(regExp);
+        Matcher matcher = pattern.matcher(text);
+        if (matcher.find()){
+            return matcher.group();
+        }
         return "";
+
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task2.java

@@ -3,6 +3,17 @@
 
 public class Task2 {
     public static String firstTwo(String s) {
-        return "";
+
+        if (s == null) {
+            return null;
+        }
+
+
+        if (s.length() < 2) {
+            return s;
+        }
+        else {
+            return s.substring(0, 2);
+        }
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task3.java

@@ -3,6 +3,20 @@
 
 public class Task3 {
     public static String comboString(String s1, String s2) {
-        return "";
+        if (s1 == null){
+            s1 = String.valueOf(s1);
+        }
+
+        if (s1.length() > s2.length())
+        {
+            StringBuilder newstring = new StringBuilder();
+            newstring.append(s2).append(s1).append(s2);
+            return newstring.toString();
+        }
+        else {
+            StringBuilder newstring2 = new StringBuilder();
+            newstring2.append(s1).append(s2).append(s1);
+            return newstring2.toString();
+        }
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task4.java

@@ -2,6 +2,24 @@
 
 public class Task4 {
     public static String charAt(String s, int i) {
-        return "";
+
+        if (s == null) {
+            return null;
+        }
+        int len = s.length();
+        if (len < 0) {
+            if (Math.abs(i) >= len) {
+                while (Math.abs(i) > len) {
+                    i = Math.abs(i) - len;
+                }
+            }
+            return String.valueOf(s.charAt(len - Math.abs(i)));
+        }
+        else {
+            if (i >= len) {
+                while (i >= len) i-= len;
+            }
+            return String.valueOf(s.charAt(i));
+        }
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task5.java

@@ -2,6 +2,6 @@
 
 public class Task5 {
     public static boolean commondEnd(int[] a, int[] b) {
-        return false;
+        return (a[0]==b[0] || a[a.length - 1]== b[b.length - 1] || a[0]==b[b.length - 1] || b[0]== a[a.length - 1]);
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task6.java

@@ -1,8 +1,14 @@
 package school.lemon.changerequest.java.introduction.hw2;
 
-
 public class Task6 {
     public static int[] reverse(int[] arr) {
-        return null;
+        if (arr == null) {
+            return null;
+        }
+        int reverseArr[] = new int[arr.length];
+        for (int i = arr.length-1; i >= 0; i--) {
+            reverseArr[arr.length - i - 1] = arr[i];
+        }
+        return reverseArr;
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task7.java

@@ -2,6 +2,15 @@
 
 public class Task7 {
     public static int countEvens(int[] arr) {
-        return 0;
+        if (arr == null) return 0;
+
+        int evenNum = 0;
+        for (int anArr : arr) {
+            if (anArr % 2 == 0) {
+                evenNum++;
+            }
+        }
+
+        return evenNum;
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task8.java

@@ -3,6 +3,22 @@
 public class Task8 {
 
     public static int[] evenOdd(int[] arr) {
-        return null;
+        if (arr == null) return null;
+
+        int sortArr[] = new int[arr.length];
+        int j = 0;
+        for (int anArr : arr) {
+            if (anArr % 2 == 0)
+                sortArr[j++] = arr[anArr];
+        }
+
+        int n = 0;
+        for (int newArr: arr) {
+            if (newArr % 2 != 0) {
+                sortArr[j + n++] = arr[newArr];
+            }
+        }
+
+        return sortArr;
     }
 }

src/main/java/school/lemon/changerequest/java/introduction/hw2/Task9.java

@@ -1,7 +1,27 @@
 package school.lemon.changerequest.java.introduction.hw2;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 public class Task9 {
     public static String[] extractData(String URL) {
-        return new String[]{"", "", ""};
+
+        if (URL == null) {
+
+            return new String[]{"", "", ""};
+        }
+        Pattern pattern = Pattern.compile("(?:([a-z]+):\\/\\/)?([\\da-z._-]+)(?::(\\d+)?)?.*");
+        //"(?:(\w+):\/\/)?([\d\w._-]+)(?::(\d+)?)?.*"
+        Matcher matcher = pattern.matcher(URL);
+
+
+        if (matcher.matches()) {
+            String scheme = matcher.group(1);
+            String host = matcher.group(2);
+            String port = matcher.group(3);
+            return new String[] {scheme != null ? scheme : "", host != null ? host : "", port != null ? port : ""};
+
+        }
+        return new String[] {"", "", ""};
     }
 }