Introduction
In this article, we are going to learn arrays class in Java. Arrays class is present in the java.util package. Arrays class concept comes under the collection framework in java. Arrays class provides several utility methods. Using the Arrays class, we can perform searches and can sort and accomplish some other tasks in easy ways.
Prerequisites:
- Basic knowledge of java
- Basic knowledge of array in java. You can learn How to use Array in Java by clicking here.
Arrays Class Methods
There are many methods that are used with arrays class. Here we are going to learn some of the important methods.
1. asList() Method
This method will return a list. We have to pass an array object as a parameter in this method.
Example
import java.util.*;
class test {
public static void main(String args[]) {
//Int List
Integer[] arr1 = new Integer[] {
10,
20,
30,
40,
50
};
List < Integer > list1 = Arrays.asList(arr1);
System.out.println("Integer List:" + list1);
//Float list
Float[] arr2 = new Float[] {
10.0 f, 20.0 f, 30.0 f, 40.0 f, 50.0 f
};
List < Float > list2 = Arrays.asList(arr2);
System.out.println("Float List:" + list2);
//String list
String arr3[] = new String[] {
"C",
"C++",
"Java",
"Python"
};
List < String > list3 = Arrays.asList(arr3);
System.out.println("String List" + list3);
}
}
Output
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Important Point
When we use the asList() method, we have to use Integer instead of int. If we use int, then we will get an error. The same rule applies to others also.
2. sort() Method
This method is used to sort an array in ascending or descending order.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
50,
40,
30,
20,
10
};
// Sort Integer Array
Arrays.sort(arr1);
for (int i = 0; i < arr1.length; i++) {
System.out.print(arr1[i] + " ");
}
//For the next line
System.out.println();
Float arr2[] = new Float[] {
50.0 f, 40.0 f, 30.0 f, 20.0 f, 10.0 f
};
// Sort Float Array
Arrays.sort(arr2);
for (int i = 0; i < arr2.length; i++) {
System.out.print(arr2[i] + " ");
}
//For the next line
System.out.println();
String arr3[] = new String[] {
"Python",
"Java",
"C",
"C++"
};
//Sort String Array
Arrays.sort(arr3);
for (int i = 0; i < arr3.length; i++) {
System.out.print(arr3[i] + " ");
}
}
}
Output
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3. binarySearch() Method
This method is used to search for an element inside a sorted array. We can apply a binary search on an array, but the array must be in sorted order. In this method, we need to pass two parameters. The first parameter is a sorted array object, and the second is a key. A key is the element that we want to search inside an array. This method will return the index value.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
int key = 30;
int index = Arrays.binarySearch(arr1, key);
System.out.print(key + " found at index: " + index);
}
}
Output
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4. equals() Method
This method is used to compare two arrays and check whether both arrays are equal or not.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
Integer arr2[] = new Integer[] {
10,
20,
30,
40,
60
};
if (Arrays.equals(arr1, arr2)) {
System.out.println("Both Arrays Are Equal");
} else {
System.out.println("Both Arrays Are Not Equal");
}
}
}
Output
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5. compare() Method
This method is used to compare two arrays. If both arrays are equal then it will return a 0 value. Otherwise, it will return a 1 or -1 value.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
Integer arr2[] = new Integer[] {
10,
20,
30,
40,
60
};
if (Arrays.compare(arr1, arr2) == 0) {
System.out.println("Both arrays are equal");
} else {
System.out.println("Both arrays are not equal");
}
}
}
Output
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6. fill() Method
This method is used to assign a particular value to a whole array or within a specified range.
Example 1
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
Arrays.fill(arr1, 60);
for (int i = 0; i < arr1.length; i++) {
System.out.print(arr1[i] + " ");
}
}
}
Here, we assign the value 60 to the whole array.
Output
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Example 2
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
Arrays.fill(arr1, 1, 3, 60);
for (int i = 0; i < arr1.length; i++) {
System.out.print(arr1[i] + " ");
}
}
}
Output
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7. mismatch() Method
This method is used to check whether or not two arrays contain a similar element. We have to pass two array objects as a parameter in this method. This method will return the index value, where the first mismatch occurred.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr1[] = new Integer[] {
10,
20,
30,
40,
50
};
Integer arr2[] = new Integer[] {
10,
20,
30,
40,
60
};
int index = Arrays.mismatch(arr1, arr2);
System.out.println("mismatched index is: " + index);
}
}
Output
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8. copyOf() Method
This method is used to create a new array from an existing array, or copy an existing array to a new array. We have to pass two parameters in this method. The first parameter is the existing array object, and the second is the size of the new array.
Example
import java.util.*;
class test {
public static void main(String args[]) {
Integer arr[] = new Integer[] {
10,
20,
30,
40,
50
};
Integer[] new_array = Arrays.copyOf(arr, 5);
for (int i = 0; i < new_array.length; i++) {
System.out.print(new_array[i] + " ");
}
}
}
Output
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Conclusion
In this article we have seen how to perform sorting, searches, and other tasks using the arrays class in Java. Thanks for reading. I hope you liked this article. If you have any suggestions or queries about this article, please share your thoughts. You can read my other articles by clicking here.
Happy learning, friends!