Class ArrayList Method toArraywhich allows the creation of a mass based on the elements of the list.Below is the demonstration programme/* package whatever; // don't place package name! */ import java.util.; import java.lang.; import java.io.*; /* Name of the class has to be "Main" only if the class is public. */ class Ideone { static int [] make_array( int n ) { int [] a = new int[n]; for ( int i = 0; i < a.length; i++ ) a[i] = i; return a; } public static void main (String[] args) throws java.lang.Exception { ArrayList<int []> lst = new ArrayList<int[]>(); for ( int i = 0; i < 10; i++ ) { lst.add( make_array( i + 1 ) ); } int[][] a = new int[lst.size()][]; lst.toArray( a ); for ( int[] row : a ) { for ( int x : row ) System.out.print( x + " " ); System.out.println(); } } } Conclusion0 0 1 0 1 2 0 1 2 3 0 1 2 3 4 0 1 2 3 4 5 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 9

Method task(arr); Even though he returns the line, he doesn't turn it off. It's worth writing. System.out.println(task(arr));Then the console will take the return method task() line.

If I understand correctly, this code has to do what you need://компаратор для сравнения объектов по полю description Comparator<Item> comparatorByDesc = (e1, e2) -> Comparator.<String>nullsFirst(Comparator.naturalOrder()).compare(e1.description, e2.description); //основной компаратор Comparator<Item> generalComparator = (e1, e2) -> { if (e1 == null || e2 == null) return Comparator.nullsLast(comparatorByDesc).compare(e1, e2); else return comparatorByDesc.compare(e1, e2); }; itemList.sort(generalComparator);

It's because it's default. lineCount Initiated by zero, further you create a zero-length mass:Point[] points = new Point[lineCount]; And after the creation of the mass, you're making sense. lineCount♪Try this:public class Point { private int lineCount; private final int x; private final int y; public Point(int x, int y) { this.x = x; this.y = y; } public int getX() { return x; } public int getY() { return y; } Point[] points; public void pointsCreator() { Scanner scanner = new Scanner(System.in); lineCount = scanner.nextInt(); points = new Point[lineCount]; System.out.println("----------------------"); System.out.println("enter points for first line: "); points[0] = pointFiller(scanner); for (int i = 1; i &lt; lineCount; i++){ System.out.println("----------------------"); System.out.println("enter points for next line:"); points[i] = pointFiller(scanner); } System.out.println("----------------------"); System.out.println(Arrays.toString(points)); } public static Point pointFiller(Scanner scanner) { System.out.print(" - enter x: "); int x = scanner.nextInt(); System.out.print(" - enter y: "); int y = scanner.nextInt(); return new Point(x, y); } @Override public String toString() { return "Points for line {x = " + x + ", y = " + y + '}'; } }

The programme may look as follows:import java.util.*; import java.lang.*; import java.io.*; class Ideone { static boolean contains(String origin, String sub) { String[] originArray = origin.split( "" ); String[] subArray = sub.split( "" ); int originLength = originArray.length; int subLength = subArray.length; boolean found = false; if ( subLength &lt;= originLength ) { for ( int i = 0; !found &amp;&amp; i &lt; originLength - subLength + 1; i++ ) { int j = 0; while ( j &lt; subLength &amp;&amp; originArray[i + j].equals( subArray[j] ) ) j++; found = j == subLength; } } return found; } public static void main (String[] args) throws java.lang.Exception { String origin = "obsensevity"; String sub = "ens"; System.out.println( "\"" + origin + "\" contains \"" + sub + "\" is " + contains( origin, sub ) ); } } Her withdrawal to the console"obsensevity" contains "ens" is true

int[] a = new int[] {1, 1, 1, 2, 1, 3, 3}; int[] b = new int[a.length]; int curIndex = 0; for (int i: a) { if (!IntStream.range(0, curIndex).anyMatch(num - > b[num] == i)) { b[curIndex++] = i; } } System.out.println(Arrays.toString(Arrays.copyOf(b, curIndex))); //[1, 2, 3] UPDATE!IntStream.range(0, b.length).anyMatch(num - > b[num] == i) to be replaced bypublic static boolean contains(int[] a, int num) { for (int i in a) { if (i == num) { return true; } } return false; } Then the main for the nextfor (int i: a) { if (!contains(b, i))) { b[curIndex++] = i; } }

If the mass is used as a matter of principle, it is possible to initialize the mass of the values obtained, for example:Integer[] intArr = {a,b,c,d,x}; It shall then apply the algorithms of minimum and maximum search. The most obvious decision I see will be:int maxArr = intArr[0]; int minArr = intArr[0]; for(Integer value : intArr) { if (value > maxArr) { maxArr = value; } if (value < minArr) { minArr = value; } } And as recommended in the commentaries, we'll be a laconutical solution using Stream API:List<Integer> list = Arrays.asList(a, b, c, d, x); Integer max = list.stream().max(Integer::compareTo).get(); Integer min = list.stream().min(Integer::compareTo).get();

You have a bad merger algorithm.You check. bools.get(i)I mean, the index among the lines. If, for example, bools.get(i) contained falseYou never increase iAnd you' through the whole cycle trying to read the meanings out of it. words (and there may be less than the total length of the reference container array.length)We need to check the general index, in your case it's just i + ii♪In addition, verification i < array.length - 1 && ii < array.length - 1 wrong. You have to. i < numbers.length || ii < words.lengthor i + ii < array.length♪(Maybe there are other mistakes, travel.)

I'll write a synonymous version, since it's probably a seal in the field, and it's impossible to do it with one length.public static int pos(String search, String where) { //искомая строка должна быть не больше той, в которой ищем if (search.length() > where.length()) { return -1; } //ищем только до определенной позиции, т.к. дальше искомая строка уже не "влезет" for (int i = 0; i < where.length() - search.length() + 1; i++) { // если совпадает первый символ ... if (where.charAt(i) == search.charAt(0)) { boolean found = true; // ... то сверим все остальные for (int j = i + 1; j < i + search.length(); j++) { // если хоть один не совпадает ... if (where.charAt(j) != search.charAt(j - i)) { // ... значит не нашли found = false; break; } } // если все символы совпали if (found) { //значит нашли и возвращаем позицию return i; } } } //ничего не нашли return -1; }

for(int i=0;i<x;i++) { if(m[i]<2) m[i]=1; else m[i]=m[i-1]+m[i-2]; } You're for every element of the mass, if it's less than two, you're giving equal weight. 1♪ And move to the next element.Since the mass is originally initiated by zeros, it is expected that you receive a body of units.

public class pathFinder { public static void main (String args[]){ int mat [][] = {{ 3,13,15,28,30}, { 40,51,52,29,30}, { 28,10,53,54,53}, { 53,12,55,53,60}, { 70,62,56,20,80}, { 80,81,90,95,100}}; System.out.println (shorterPath(mat)); } public static int shorterPath(int[][]mat) { return shorterPath(mat,0,0,0,0); } public static int shorterPath(int[][]mat,int i,int j,int counter,int preval) { if(!isValid(mat,i,j)|| preval >= mat[i][j]) return mat.length*mat[0].length*2; if (i==mat.length-1 && j== mat[0].length-1) { counter++; return counter; } else { int a=shorterPath(mat,i+1,j,counter+1,mat[i][j]); int b=shorterPath(mat,i-1,j,counter+1,mat[i][j]); int c=shorterPath(mat,i,j+1,counter+1,mat[i][j]); int d=shorterPath(mat,i,j-1,counter+1,mat[i][j]); if(a<=b && a<=c && a<=d) return a; if(b<=a && b<=c && b<=d) return b; if(c<=a && c<=b && c<=d) return c; return d; } } public static boolean isValid(int[][]a,int i,int j) { if(i>=0 && i<=a.length-1 && j>=0 && j<= a[0].length-1) return true; else return false; } ♪

The use of fluxes accelerates the code for calculations, as there is a python https://ru.wikipedia.org/wiki/Global_Interpreter_Lock ♪ Use the code to speed up. Process from module multiprocessing or ProcessPoolExecutor from module concurrent♪

Let's drop the question of efficiency while you're doing it.StringTokenizer sTokenizer = new StringTokenizer(stringArray[i]); int tokens = sTokenizer.countTokens(); You've got a number of words. i an element of the mass. You're doing it.if (stringArray[j].compareTo(stringArray[i]) < tokens It's kind of weird.Write about that.StringTokenizer sTokenizerL = new StringTokenizer(stringArray[i]); int tokensL = sTokenizerL.countTokens(); StringTokenizer sTokenizerR = new StringTokenizer(stringArray[j]); int tokensR = sTokenizerR.countTokens(); if ( tokensL < tokensR) //swap But implementation is extremely inefficient. I'd rather do something like that.class Pair implements Comparable { public int tokenCount; public String string; public Pair(String string){ this.string = string; StringTokenizer sTokenizer = new StringTokenizer(string); tokenCount = sTokenizer.countTokens(); } public int compareTo(Object obj){ Pair other = (Pair)obj; return tokenCount - other.tokenCount; } public String toString(){ return string; } } And use it to sort it through standard method Arrays.sort

If you don't think too hard about cryptographic persistence,Collections.shuffle(list);

Look, you're going through the cycle. zaoshad+1, and the mass creates a size zaoshad♪ I mean, there's a way out of size, so you're fighting. Capitalization must be considered as such:for (int i=0; i < zaoshad; i++) { if (i>0) mass[i] = vklad + mass[i-1] + mass[i-1]*stavka/100; else mass[i] = vklad; System.out.println("Возраст = " + (age + i) + " накопление = " + mass[i]); }

With regard to the underlined red: You're challenging the lastModified method at String. You're running in a series of Strings. File's still on the basis of this line, and only then can he call lastModified. TreeMap Until your cycle is ready, create an empty TreeMap.Inside the cycle, using the name of the file, create the File object.Put it in the mob.Example of working codepackage ru.yaklimenko; import java.io.File; import java.net.URL; import java.util.*; public class Main { static final String CLASS_FILE_EXTENSION = ".class"; /** * сортировка по дате последних изменений */ static final Comparator&lt;File&gt; MODIFIED_DATE_FILE_COMPARATOR = new Comparator&lt;File&gt;() { @Override public int compare(File o1, File o2) { if (o1.lastModified() &lt; o2.lastModified()) { return -1; } else if (o1.lastModified() == o2.lastModified()) { return o1.getAbsolutePath().compareToIgnoreCase(o2.getAbsolutePath()); } return 1; } }; public static void main(String[] args) { TreeMap&lt;File, Class&gt; classesByFiles = find("ru.yaklimenko", ""); // получил мапу List&lt;File&gt; files = new ArrayList&lt;&gt;(classesByFiles.keySet()); //получил список файлов из мапы Collections.sort(files, MODIFIED_DATE_FILE_COMPARATOR);// посортировал // теперь можно бежать по отсортированному циклу и брать классы сначала от старых файлов двигаясь к более молодым for (File file : files) { Class cls = classesByFiles.get(file); //do something } } /** * метод соберет и разложит по мапе классы из заданного package */ public static TreeMap&lt;File, Class&gt; find(String pkgname, String beginStr) { List&lt;Class&gt; classes = new ArrayList&lt;Class&gt;(); ArrayList&lt;Long&gt; Dates = new ArrayList&lt;Long&gt;(); String relPath = pkgname.replace('.', '/'); URL resource = ClassLoader.getSystemClassLoader().getResource(relPath); assert resource != null; File directory = new File(resource.getPath()); if (directory != null &amp;&amp; directory.exists()) { // Получаем список всех файлов в папке String[] files = directory.list(); TreeMap&lt;File, Class&gt; resMap = new TreeMap&lt;&gt;(); for (int i = 0; i &lt; files.length; i++) { // Берем только файлы с расширением .class if (!files[i].endsWith(CLASS_FILE_EXTENSION)) { continue; } File file = new File(files[i]); // Убираем расширение //new Date(files[i].lastModified()) String className = files[i].substring(0, files[i].lastIndexOf('.')); try { resMap.put(file, Class.forName(pkgname + "." + className)); } catch (ClassNotFoundException e) { e.printStackTrace(); } //я не понял, зачем эти 3 строки ниже из оригинального кода if (className.toLowerCase().substring(0, beginStr.length()).equals(beginStr.toLowerCase())) { String fullClassName = pkgname + '.' + className; } } return resMap; } return null; } }

https://stackoverflow.com/a/18581313/3212712 There is a detailed description of the problem in English.I think it should work like this:public <E> E[] getArray(Class<E> clazz, int size) { @SuppressWarnings("unchecked") E[] arr = (E[]) Array.newInstance(clazz, size); return arr; }

It's not necessary to inherit classes from some general class: they all inherit. Object♪ The simplest option (not the best in terms of practical use, but the most challenging task):public static Object[] fill() { Object[] array = new Object[10]; Object obj = null; Random randomizer = new Random(); for (int i=0; i<10; i++) { int randomNumber = randomizer.nextInt(3); switch(randomNumber) { case 0: obj = new Car(); break; case 1: obj = new Bicycle(); break; case 2: obj = new Bike(); break; } array[i] = obj; } return array; } Method of verification:public static void main(String[] args) { for (Object o:fill()) { System.out.println(o); } } Exhibition on the screen. ComplexNumbercom.company.ComplexNumber$Bicycle@677327b6 com.company.ComplexNumber$Bike@14ae5a5 com.company.ComplexNumber$Car@7f31245a com.company.ComplexNumber$Car@6d6f6e28 com.company.ComplexNumber$Bike@135fbaa4 com.company.ComplexNumber$Bike@45ee12a7 com.company.ComplexNumber$Bicycle@330bedb4 com.company.ComplexNumber$Bicycle@2503dbd3 com.company.ComplexNumber$Bike@4b67cf4d com.company.ComplexNumber$Bicycle@7ea987acIt's obvious that the mass is filled with objects of different classes.

How can you check the line on the void?String d = ""; String[] s = {"26", "8", "15", "12", "11", "12"}; for (int i = 0; i < s.length; i++) { if (s[i].equals("12")) { d += s[i]; } } if(d.isEmpty()) d = "0"; System.out.println(d);

In terms of incubation, it doesn't matter's how your methods are going to get the data from the body and what to do with it, it's just an interface that's "stop" outside. Therefore, if there is a need for external users to renumber the unit starting from the unit, the most correct would be to remove the unit within the relevant methods (in which the index is transmitted). If you write null first, you'll have an inconsistency. size()-1And you'll have the first null, and the key elements will be size()-2the code will be confusing and unclear. There's no win-win.