Вывести массив java одной строкой

How to convert an array to a string in Java

Sometimes you want to convert an array of strings or integers into a single string. However, unfortunately, there is no direct way to perform this conversion in Java.

The default implementation of the toString() method on an array only tells us about the object’s type and hash code and returns something like [Ljava.lang.String;@f6f4d33 as output.

In this article, we shall look at different ways to convert an array into a string in Java.

The String.join() method returns a new string composed of a set of elements joined together using the specified delimiter:

String[] fruits = "Apple", "Orange", "Mango", "Banana">; String str = String.join(", ", fruits); System.out.println(str); // Apple, Orange, Mango, Banana 

You can also pass the strings that you want to join directly to the String.join() method, as shown below:

String str = String.join(" ", "Java", "is", "awesome", "🌟"); System.out.println(str); // Java is awesome 🌟 

ListString> animals = List.of("Fox", "Dog", "Loin", "Cow"); String str = String.join("-", animals); System.out.println(str); // Fox-Dog-Loin-Cow CharSequence[] vowels = "a", "e", "i", "o", "u">; String str2 = String.join(",", vowels); System.out.println(str2); // a,e,i,o,u 

Java Streams API provides the Collectors.joining() method to join strings from the Stream using a delimiter:

String[] fruits = "Apple", "Orange", "Mango", "Banana">; String str = Arrays.stream(fruits).collect(Collectors.joining(", ")); System.out.println(str); // Apple, Orange, Mango, Banana 

Besides delimiter, you can also pass prefix and suffix of your choice to the Collectors.joining() method:

String[] fruits = "Apple", "Orange", "Mango", "Banana">; String str = Arrays.stream(fruits) .collect(Collectors.joining(", ", "[", "]")); System.out.println(str); // [Apple, Orange, Mango, Banana] 

The Arrays.toString() method returns a string representation of the contents of the specified array. All array’s elements are joined together using a comma ( , ) as a delimiter and enclosed in square brackets ( [] ) as shown below:

String[] fruits = "Apple", "Orange", "Mango", "Banana">; String str = Arrays.toString(fruits); System.out.println(str); // [Apple, Orange, Mango, Banana] 

The best thing about Arrays.toString() is that it accepts both primitive and object arrays and converts them into a string:

int[] number = 1, 2, 3, 4>; System.out.println(Arrays.toString(number)); // [1, 2, 3, 4] double[] prices = 3.46, 9.89, 4.0, 2.89>; System.out.println(Arrays.toString(prices)); // [3.46, 9.89, 4.0, 2.89] 

The StringBuilder class is used to create mutable strings in Java. It provides an append() method to append the specified string to the sequence. The toString() method of the StringBuilder class returns a string representation of the data appended. To convert an array to a string using StringBuilder , we have to use a loop to iterate over all array’s elements and then call the append() method to append them into the sequence:

String[] fruits = "Apple", "Orange", "Mango", "Banana">; StringBuilder builder = new StringBuilder(); for (int i = 0; i  fruits.length; i++)  builder.append(fruits[i]).append(" "); > String str = builder.toString(); System.out.println(str); // Apple Orange Mango Banana 

int[] number = 1, 2, 3, 4>; StringBuilder builder = new StringBuilder(); for (int i = 0; i  number.length; i++)  builder.append(number[i]).append(" "); > String str = builder.toString(); System.out.println(str); // 1 2 3 4 

The StringJoiner class was introduced in Java 8, and it provides methods for combining multiple strings into a single string using the specified delimiter:

String path = new StringJoiner("/") .add("/usr") .add("share") .add("projects") .add("java11") .add("examples").toString(); System.out.println(path); // /usr/share/projects/java11/examples 

As you can see above, the StringJoiner class provides a very fluent way of joining strings. We can easily chain multiple calls together to build a string.

Finally, the last way to convert an array of strings into a single string is the Apache Commons Lang library. The join() method of the StringUtils class from Commons Lang transforms an array of strings into a single string:

String[] names = "Atta", "Arif", "Meero", "Alex">; String str = StringUtils.join(names, "|"); System.out.println(str); // Atta|Arif|Meero|Alex 

To convert a string back into an array in Java, read this article. ✌️ Like this article? Follow me on Twitter and LinkedIn. You can also subscribe to RSS Feed.

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How to print array in java

In this post, we will see how to print array in java.

There are multiple ways to print an array. Let’s go through few ways to print array in java.

Using Arrays.toString()

You can use Arrays.toString() method to print array in java. This is simplest ways to print an array.
Arrays.toString() returns string object.This String contains array in string format.
Let us understand with the code

Using deepToString() method

Basically Arrays.toString() works fine for a 1-dimensional arrays,but it won’t work for multidimensional arrays.
Let’s say we have 2-dimensional array as shown
1 2 3
4 5 6
7 8 9
To convert multidimensional arrays to string, you can use Arrays.deepToString() method. This is how you can print 2D array in java.

Using Java 8 Stream API

In java 8, you can convert array to Stream and print array with Stream’s foreach() method.

Arrays . stream ( string2DArray ) . flatMap ( str — > Arrays . stream ( str ) ) . forEach ( System . out : : println ) ;

Arrays . stream ( int2DArray ) . flatMapToInt ( i — > Arrays . stream ( i ) ) . forEach ( System . out : : println ) ;

As you can see we have seen how to print String array and Integer array in java using Stream.

Using for loop

You can iterate the array using for loop and print elements of array in java.

Using for-each loop

For each works same as for loop but with differs syntax.

Print array in reverse order in java

You can iterate the array using for loop in reverse order and print the element. This will print array in reverse order.

Print array with custom objects

In case, you have custom object in the array, then you should override toString() method in custom class, else it will give you unexpected results.
Let’s see with the help of example
Create a simple class named Color.java

Create main class named PrintArrayOfColors.java

If you notice, we don’t have toString() method in Color class, that’s why it is calling Object’s toString() method and we are not able to see meaningful results.

We need to override toString() method in Color class and we will get informative output.

When you run PrintListOfColorsMain again, you will get below output:

As you can see, we have much meaningful output now.

That’s all about how to print array in java.

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Преобразование массива в строку в Java

1. Преобразование массива в строку с помощью метода Arrays.toString() в Java
2. Преобразование массива в строку с помощью метода String.join() в Java
3. Преобразование массива в строку с помощью метода Arrays.stream() в Java

В этом руководстве мы увидим, как преобразовать массив в строку различными способами в Java. Массив состоит из элементов одного типа данных, а строка — это просто набор символов. В следующих примерах мы рассмотрим три метода преобразования массива в строку.

Преобразование массива в строку с помощью метода Arrays.toString() в Java

Arrays — это класс, содержащий различные статические методы, которые могут управлять массивами. Одна из полезных функций Arrays — это toString (), которая принимает массив различных типов данных, таких как int и char, и возвращает строковое представление массива.

В этом примере мы создаем массив arrayOfInts типа int и заполняем его несколькими элементами. Чтобы преобразовать arrayOfInts в строку, мы используем Arrays.toString() и передаем его в качестве аргумента, возвращающего строку arrayToString , которую мы печатаем в выводе.

import java.util.Arrays;  public class ArrayToString   public static void main(String[] args)    int[] arrayOfInts = 1, 3, 9, 11, 13>;   String arrayToString = Arrays.toString(arrayOfInts);   System.out.println(arrayToString);   > > 

Преобразование массива в строку с помощью метода String.join() в Java

Метод join() был добавлен в класс String с выпуском JDK 8. Эта функция возвращает строку, объединенную с указанным разделителем. join() принимает разделитель и элементы в качестве аргументов.

В коде есть массив типа String . Мы вызываем метод String.join() и передаем пробел в качестве разделителя, а также массив, элементы которого будут объединены пробелом.

Вывод показывает все элементы массива, разделенные пробелами.

public class ArrayToString   public static void main(String[] args)    String[] arrayOfStrings = "One", "Two", "Three", "four", "Five">;   String arrayToString = String.join(" ", arrayOfStrings);   System.out.println(arrayToString);   > > 

Преобразование массива в строку с помощью метода Arrays.stream() в Java

В этом примере мы используем Stream API, представленный в JDK 8. Arrays.stream() принимает массив. Метод collect() возвращает результат после выполнения указанной операции над каждым элементом массива. Здесь мы выполняем операцию Collectors.joining() над элементами массива, которая собирает элементы и объединяет их для возврата в виде целой строки.

import java.util.Arrays; import java.util.stream.Collectors;  public class ArrayToString   public static void main(String[] args)    String[] arrayOfStrings = "One", "Two", "Three", "four", "Five">;   String arrayToString = Arrays.stream(arrayOfStrings).collect(Collectors.joining());   System.out.println(arrayToString);   > > 

Rupam Saini is an android developer, who also works sometimes as a web developer., He likes to read books and write about various things.

Сопутствующая статья — Java Array

Сопутствующая статья — Java String

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