Java String Array Example (original) (raw)

Last updated Jan. 14, 2019

In this example we will show how to declare and populate a Java String Array as well as how to iterate through all its elements.

Create a java class named JavaStringArrayExample.java with the following code:

JavaStringArrayExample.java

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

// declare a string array with initial size String[] schoolbag = new String[4];

// add elements to the array schoolbag[0] = "Books"; schoolbag[1] = "Pens"; schoolbag[2] = "Pencils"; schoolbag[3] = "Notebooks";

// this will cause ArrayIndexOutOfBoundsException // schoolbag[4] = "Notebooks"; } }

Let’s give a short explanation of the above code. First, we declare a string array with an initial size of 4 elements and then add 4 elements. If you try to add one more element, you will have java.lang.ArrayIndexOutOfBoundsException, as the capacity of the array is fixed and cannot be resized once created. If you want a dynamically sized array where you can add and remove the objects and the size is adjusted accordingly, you should use an ArrayList. You can have a look at How to use ArrayList example.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) { // declare a string array with no initial size // String[] schoolbag;

// declare string array and initialize with values in one step String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

// print the third element of the string array System.out.println("The third element is: " + schoolbag2[2]); } }

Next, we defined another string array named schoolbag2 as it is more common to declare and populate a string array in one step.

Output:

The third element is: Pencils

Now, we will show two ways of iterating through all the elements of the array.

The first one is a more “traditional way”, by using the standard for loop mechanism and the size of the array.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

// iterate all the elements of the array int size = schoolbag.length; System.out.println("The size of array is: " + size);

for (int i = 0; i < size; i++) { System.out.println("Index[" + i + "] = " + schoolbag[i]); } } }

Output:

The size of array is: 4
Index[0] = Books
Index[1] = Pens
Index[2] = Pencils
Index[3] = Notebooks

The second way uses the enhanced for loop example, which was introduced in Java 5.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

// iteration provided by Java 5 or later for (String str : schoolbag) { System.out.println(str); } }

Output:

Books
Pens
Pencils
Notebooks

Let’s now test if a string array contains a value.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

String findString = "Pens"; boolean found = false; for (String element:schoolbag) { if (element.equals(findString)) { found = true; break; } } if (found) { System.out.println("The array contains the string: " + findString); } else { System.out.println("The array does not contain the string: " + findString); } } }

Next let’s see how to sort a string array.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

Arrays.sort(schoolbag); for (String element : schoolbag) { System.out.println(element); } } }

Output:

Books
Notebooks
Pencils
Pens

Now we are going to convert a string array into a string.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = { "Books", "Pens", "Pencils", "Notebooks" };

String s = Arrays.toString(schoolbag); System.out.println(s); } }

Output:

[Books, Pens, Pencils, Notebooks]

Let’s see how to convert a string array into a set.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[] schoolbag = {"Books", "Pens", "Pens"}; List stringList = Arrays.asList(schoolbag); Set stringSet = new HashSet(stringList); System.out.println("Size of the list is: " + stringList.size()); System.out.println("Size of the set is: " + stringSet.size()); } }

Output:

Size of the list is: 3
Size of the set is: 2

So now we will see how to convert a list into a string array.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

List stringList = new ArrayList(); stringList.add("Books"); stringList.add("Pens"); stringList.add("Pencils"); stringList.add("Notebooks");

String[] schoolbag = stringList.toArray( new String[] {} );

for (String element : schoolbag) { System.out.println(element); } } }

Output:

Books
Pens
Pencils
Notebooks

Finally, let’s see the two-dimensional string array.

package com.javacodegeeks.javabasics.stringarray;

public class JavaStringArrayExample {

public static void main(String args[]) {

String[][] schoolbagArray = new String[4][2]; schoolbagArray[0] = new String[] {"Pens", "Pencils"}; schoolbagArray[1] = new String[] {"Books", "Notebooks"}; System.out.println( schoolbagArray [1][0] ); } }

Output:

Books

2. Download the source code

This was an example of Java String Array. You can download the source code from here: StringArrayExample.zip

Konstantina has graduated from the Department of Informatics and Telecommunications in National and Kapodistrian University of Athens (NKUA) and she is currently pursuing M.Sc studies in Advanced Information Systems at the same department. She is also working as a research associate for NKUA in the field of telecommunications. Her main interests lie in software engineering, web applications, databases and telecommunications.