Recenzja

arrays/Arrays.jsh

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+void s(long time){
+	try{
+		Thread.sleep(time);
+	} catch (InterruptedException e){
+	}
+}
+System.out.println("An array is a container object that holds a fixed number of values of a single type.");
+System.out.println("The length of an array is established when the array is created. ");
+System.out.println("Each item in an array is called an element, and each element is accessed by its numerical index.");
+System.out.println();
+s(2000);
+System.out.println("It's time for questions.");
+System.out.println("Write /open ../arrays/Q1.jsh");

arrays/E1.jsh

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+if(answer == 2){
+        System.out.println("You're right!");
+        correct++;
+} else{
+        System.out.println("Too bad :(");
+}
+System.out.println("When we create new array, it is fill by default values, so for logical boolean it will be false.\n" +
+"If condition is true, so program will print num variable.");
+s(4000);
+System.out.println("You have " + correct + " correct answers on 8 possible");
+System.out.println("If you aren't satisfied you know what to do");
+if(correct == 8){
+        System.out.println("I can't believe you are so smart..");
+}
+System.out.println();
+System.out.println("And now very basic problem. You have an array and want to reverse it. Return array with a new order.");
+System.out.println("For example, [1, 2, 3] -> [3, 2, 1]");
+System.out.println("Type your method in JShell and named it reverse");
+System.out.println("When you finish, write /open ../arrays/E2.jsh");

arrays/E2.jsh

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+System.out.println("Your method:");
+/list reverse
+s(5000);
+System.out.println();
+System.out.println("Now we will test it for this calls:");
+System.out.println("\treverse([1, 2, 3]) -> [3, 2, 1]");
+System.out.println("\treverse([1, 2, 3, 1, 2, 3]) -> [3, 2, 1, 3, 2, 1]");
+System.out.println("\treverse([0, 0, 0, 0]) -> [0, 0, 0, 0]");
+System.out.println("\treverse([]) -> []");
+s(4000);
+System.out.println();
+if (!Arrays.equals(reverse(new int[]{1, 2, 3}),new int[]{3, 2, 1})) {
+            System.out.println("First test didn't work.");
+        } else if (!Arrays.equals(reverse(new int[]{1, 2, 3, 1, 2, 3}),new int[]{3, 2, 1, 3, 2, 1}))  {
+            System.out.println("Second test didn't work.");
+        } else if (!Arrays.equals(reverse(new int[]{0, 0, 0, 0}), new int[]{0, 0, 0, 0})) {
+            System.out.println("Third test didn't work.");
+        } else if (!Arrays.equals(reverse(new int[]{}),new int[]{})) {
+            System.out.println("Fourth test didn't work.");
+        } else {
+            System.out.println("Wow. You passed all tests. Congratulations such a feat!");
+        }
+
+public int[] rightReverse(int[] nums) {
+  int[] temp = new int[nums.length];
+	//two conditions in loop to iterate over two arrays
+        for(int i = nums.length - 1, j = 0; i >= 0 & j < nums.length; i--, j++){
+            temp[i] = nums[j];
+        }
+        return temp;
+}
+
+
+System.out.println("Something wrong with your solution?");
+System.out.println("When you type /list rightReverse you can see how to do this exercise");
+
+System.out.println("Then write /open ../arrays/E3.jsh");

arrays/E3.jsh

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+System.out.println();
+System.out.println("Next task for you");
+System.out.println("Write method which takes array of int and returns array consist of max value from given array.\n" + 
+"For example: [3, 4, 3, 12, 7, 9] -> [12, 12, 12, 12, 12, 12]");
+System.out.println("Name your method maxValues");
+System.out.println("Remember that you can use /list methodName command to see what you wrote");
+System.out.println("When you finish, write /open ../arrays/E4.jsh");

arrays/E4.jsh

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+System.out.println("Your method looks like that:");
+/list maxValues
+Thread.sleep(5000);
+System.out.println();
+System.out.println("Now we will test it for this calls:");
+System.out.println("\tmaxValues([1, 2, 3]) -> [3, 3, 3]");
+System.out.println("\tmaxValues([2, 16, 6, 18, 8, 10]) -> [18, 18, 18, 18, 18, 18]");
+System.out.println("\tmaxValues([5, 5, 5]) -> [5, 5, 5]");
+System.out.println("\tmaxValues([3, 0, -5, 2]) -> [3, 3, 3, 3]");
+System.out.println("\tmaxValues([-3, -5, -2]) -> [-2, -2, -2]");
+s(4000);
+System.out.println();
+if (!Arrays.equals(maxValues(new int[]{1, 2, 3}),new int[]{3, 3, 3})){
+            System.out.println("First test didn't work.");
+        } else if (!Arrays.equals(maxValues(new int[]{2, 16, 6, 18, 8, 10}),new int[]{18, 18, 18, 18, 18, 18})){
+            System.out.println("Second test didn't work.");
+        } else if (!Arrays.equals(maxValues(new int[]{5, 5, 5}),new int[]{5, 5, 5})) {
+            System.out.println("Third test didn't work.");
+        } else if (!Arrays.equals(maxValues(new int[]{3, 0, -5, 2}),new int[]{3, 3, 3, 3})) {
+            System.out.println("Fourth test didn't work.");
+        } else if (!Arrays.equals(maxValues(new int[]{-3, -5, -2}),new int[]{-2, -2, -2})) {
+            System.out.println("Fourth test didn't work.");
+        } else {
+            System.out.println("Wow. You passed all tests. Congratulations such a feat!");
+        }
+
+public int[] rightMaxValues(int[] nums) {
+  //finds max value at the end of array
+  Arrays.sort(nums);
+  //fill array with founded value
+  Arrays.fill(nums, nums[nums.length - 1]);
+  return nums;
+}
+
+
+System.out.println("When you type /list rightMaxValues you can see how to do this exercise");
+
+System.out.println("Then write /open ../arrays/E5.jsh");

arrays/E5.jsh

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+System.out.println();
+System.out.println("Next task");
+System.out.println("You have to connect two arrays in one.\n" +
+"For example: [1, 2, 3], [5, 6, 7] -> [1, 2, 3, 5, 6, 7]");
+System.out.println("Return new array.");
+System.out.println("Named your method joinArrays");
+System.out.println("When you finish, write /open ../arrays/E6.jsh");

arrays/E6.jsh

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+System.out.println("Your method:");
+/list joinArrays
+Thread.sleep(5000);
+System.out.println();
+System.out.println("And we will test it for this calls:");
+System.out.println("\tjoinArrays([1, 2, 3], [5, 6, 7]) -> [1, 2, 3, 5, 6, 7]");
+System.out.println("\tjoinArrays([1, 2, 3], []) -> [1, 2, 3]");
+System.out.println("\tjoinArrays([], [5, 6, 7]) -> [5, 6, 7]");
+System.out.println("\tjoinArrays([1, 2], [5, 6, 7]) -> [1, 2, 5, 6, 7]");
+System.out.println("\tjoinArrays([1, 2, 3], [5, 6]) -> [1, 2, 3, 5, 6]");
+s(4000);
+System.out.println();
+if (!Arrays.equals(joinArrays(new int[]{1, 2, 3}, new int[]{5, 6, 7}), new int[]{1,2,3,5,6,7})) {
+            System.out.println("First test didn't work.");
+        } else if (!Arrays.equals(joinArrays(new int[]{1, 2, 3}, new int[]{}), new int[]{1,2,3})) {
+            System.out.println("Second test didn't work.");
+        } else if (!Arrays.equals(joinArrays(new int[]{}, new int[]{5, 6, 7}), new int[]{5,6,7})) {
+            System.out.println("Third test didn't work.");
+        } else if (!Arrays.equals(joinArrays(new int[]{1, 2}, new int[]{5, 6, 7}), new int[]{1,2,5,6,7})) {
+            System.out.println("Fourth test didn't work.");
+        } else if (!Arrays.equals(joinArrays(new int[]{1, 2, 3}, new int[]{5, 6}), new int[]{1,2,3,5,6})) {
+            System.out.println("Fifth test didn't work. Most importatnt!");
+        } else {
+            System.out.println("Wow. You passed all tests. Congratulations such a feat!");
+        }
+
+public int[] rightJoinArrays(int[] a, int[] b) {
+  //checks if one of arrays is empty
+  if(a.length == 0){
+	return b;
+  }
+  if(b.length == 0){
+	return a;
+  }
+  //create an array to contaions two given
+  int[] arr = new int[a.length + b.length];
+	//copy first array at the begining
+        System.arraycopy(a, 0, arr, 0, a.length);
+	//copy second array at place where first was finished
+        System.arraycopy(b, 0, arr, a.length, b.length);
+        return arr;
+}
+
+
+System.out.println("When you type /list rightJoinArrays you can see how to do this exercise");
+
+System.out.println("Then write /open ../arrays/E7.jsh");

arrays/E7.jsh

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+System.out.println();
+System.out.println("The last one task");
+System.out.println("Yoir methods takes two parameters, first is an array, and second is a number, which tells how many times move array elements.\n" +
+"For example: [1, 2, 3, 4], 2 -> [3, 4, 1, 2]");
+System.out.println("Remember that order can returns to initial state or go through the array several times.");
+System.out.println("Named your method move");
+System.out.println("When you finish, write /open ../arrays/Finish.jsh");

arrays/Finish.jsh

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+System.out.println("Your method:");
+/list move
+Thread.sleep(5000);
+System.out.println();
+System.out.println("And we will test it for this calls:");
+System.out.println("\tmove([1, 2, 3, 4, 5], 1) -> [5, 1, 2, 3, 4]");
+System.out.println("\tmove([1, 2, 3, 4, 5], 0) -> [1, 2, 3, 4, 5]");
+System.out.println("\tmove([1, 2, 3, 4, 5], 3) -> [3, 4, 5, 1, 2]");
+System.out.println("\tmove([1, 2, 3, 4, 5], 5) -> [1, 2, 3, 4, 5]");
+System.out.println("\tmove([1, 2, 3, 4, 5], 7) -> [4, 5, 1, 2, 3]");
+s(4000);
+System.out.println();
+
+if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 1), new int[]{5,1,2,3,4})) {
+            System.out.println("First test didn't work.");
+        } else if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 1), new int[]{5,1,2,3,4})) {
+            System.out.println("Second test didn't work.");
+        } else if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 0), new int[]{1,2,3,4,5})) {
+            System.out.println("Third test didn't work.");
+        } else if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 3), new int[]{3,4,5,1,2})) {
+            System.out.println("Fourth test didn't work.");
+        } else if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 5), new int[]{1,2,3,4,5})) {
+            System.out.println("Fifth test didn't work. Most importatnt!");
+        } else if (!Arrays.equals(move(new int[]{1, 2, 3, 4, 5}, 7), new int[]{4,5,1,2,3})) {
+            System.out.println("Sixth test didn't work. Most importatnt!");
+        }else {
+            System.out.println("Wow. You passed all tests. Congratulations such a feat!");
+        }
+
+public int[] rightMove(int[] arr, int times){
+	//checks if array can stay without changes
+        if (times%arr.length == 0 || times == 0){
+            return arr;
+        }
+	//checks if number of moves can be repeated
+        if (times > arr.length){
+            times = times%arr.length;
+        }
+        int[] moved = new int[arr.length];
+        for (int i = 0; i < arr.length; i++){
+	    //for first part of array
+            if (i < arr.length - times){
+		//puts elements moved by number of times
+                moved[i + times] = arr[i];
+            } else{
+                moved[i - (arr.length - times)] = arr[i];
+            }
+        }
+        return moved;
+    }
+
+
+System.out.println("When you type /list rightMove you can see how to do this exercise");
+
+System.out.println();
+System.out.println("That's all for now. Try to do more exercises for example on page https://codingbat.com/java");
+System.out.println("Read also documentation and oracle tutorials.");

arrays/Q1.jsh

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+int answer = 0;
+int correct = 0;
+System.out.println("Which array creations are proper?\na: int[] a = new int[5];\nb: int[5] b = new int[];\nc: int[] c = {1,2,3};\n" +
+"d: int d[] = new int[5];\ne: int[] e[] = new int[5];");
+System.out.println("1. all");
+System.out.println("2. a, c, d");
+System.out.println("3. a, b, c");
+System.out.println("Please, declare your answer as answer number.");
+System.out.println("And /open ../arrays/Q2.jsh");
+
+

arrays/Q2.jsh

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+void declare(){
+	System.out.println("Remember to declare answer");
+}
+if(answer == 2){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("Possible creations for one dimensional array:\nint[] a = new int[5];\nint b[] = new int[5];\nint[] c = {1,2,3};\n" + 
+"int[] d = new int[]{1,2,3};\nThe size of the array is not part of its type (which is why the brackets are empty).");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("How can't we declare multidimensional array?");
+System.out.println("1. int[][] arr = new int[3][];");
+System.out.println("2. int[][] arr = new int[3][3];");
+System.out.println("3. int[][] arr = new int[][];");
+declare();
+System.out.println("Write /open ../arrays/Q3.jsh");
+
+

arrays/Q3.jsh

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+
+if(answer == 3){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("Multidimensional array is an array of arrays. Each element contains an array.\n" + 
+"We must provide at least first size of array. Second size can be add dynamically.");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("What will be the size of  int[][] arr = new int[3][4];?\nThe result of arr.length");
+System.out.println("1. 12");
+System.out.println("2. 3");
+System.out.println("3. 7");
+declare();
+System.out.println("Write /open ../arrays/Q4.jsh");
+
+

arrays/Q4.jsh

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+
+if(answer == 2){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("Length is a final field which contains number of elements in array.\n" + 
+"In multidimensional array each element is an array, but its sizes don't add up.");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("What is class and superClass of int intArray[] = new int[3];");
+System.out.println("1. class is [I and superClass is java.lang.Object");
+System.out.println("2. class is java.lang.Object and superClass doesn't exist");
+System.out.println("3. arrays aren't a class");
+declare();
+System.out.println("Write /open ../arrays/Q5.jsh");
+
+

arrays/Q5.jsh

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+
+if(answer == 1){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("All arrays are an object. Result of arr.getClass() is 'class [I' for int typ,\n" +
+"'class [B' for byte type, 'class [S' for short type, 'class [Ljava.lang.String' for String.\n" + 
+"And the result of arr.getClass().getSuperclass() is 'class java.lang.Object'. \n" +
+"Because of that we can call all of Object methods on array.");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("What will be the result of arrays comparison:\n" +
+"(new int[]{1, 2, 3}).equals(new int[]{1, 2, 3})");
+System.out.println("1. true");
+System.out.println("2. false");
+System.out.println("3. compilation error");
+declare();
+System.out.println("Write /open ../arrays/Q6.jsh");
+
+

arrays/Q6.jsh

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+
+if(answer == 2){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("Comparison of arrays is \"shallow\", so we don't compare elements of array.\n" + 
+"To do that we must use Arrays.equals() method.");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("What will be the result of such operation:\n" +
+"\tint[] max = new int[3_000_000_000];");
+System.out.println("1. runtime error");
+System.out.println("2. array of size 3_000_000_000 conteining elements equal 0");
+System.out.println("3. compilation error");
+declare();
+System.out.println("Write /open ../arrays/Q7.jsh");
+
+

arrays/Q7.jsh

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+
+if(answer == 3){
+	System.out.println("You're right!");
+	correct++;
+} else{
+	System.out.println("Too bad :(");
+}
+System.out.println("Compilator will tell that \"Integer number too large\", because range of int was exceeded.\n" +
+"If you don't know why, go back to primitives questions.");
+s(4000);
+System.out.println();
+System.out.println("Next question");
+System.out.println("What will be the result of such operation:\n" +
+"\tbyte[] max = new byte[150];");
+System.out.println("1. runtime error");
+System.out.println("2. array of size 150 conteining elements equal 0");
+System.out.println("3. compilation error");
+declare();
+System.out.println("Write /open ../arrays/Q8.jsh");
+
+