Methods of the array class

Methods of the array class


Posted in : Core Java Posted on : October 14, 2010 at 4:05 PM Comments : [ 0 ]

This section contains the detail about the Methods of the array class in java.

Methods of the array class

The "java.util.Arrays" is the base class for arrays in Java which have many static methods for searching, sorting, comparing and filling arrays. All primitive type can be overloaded  using these methods. The main methods are given below :

         Method           Description       
public static int binarySearch(Object[] a, Object key)    Searches the specified array for the specified
object using the binary search algorithm.
public static boolean equals(long[] a, long[] a2)  Returns true if the two specified arrays of longs
are equal to one another.
public static void fill(int[] a, int val) Assigns the specified int value to each element of
the specified array of ints.
public static void sort(Object[] a)  Sorts the specified array of objects into ascending
order, according to the natural ordering of its elements.

Click here to see complete list of Array methods

Examples :

sort() & binarysearch() Methods' Example :


import java.util.Arrays;

public class DevClass {
public static void main(String args[]) throws Exception {
int DevArray[] = { 1, 3, 2, 5, -2, 6, -3, 8, 0, -7, -9, 4 };
Arrays.sort(DevArray);
printArray("Sorted array", DevArray);
int index = Arrays.binarySearch(DevArray, 2);
System.out.println("2 is found at index " + index);
}

private static void printArray(String message, int DevArray[]) {
System.out.println(message + ": [length: " + DevArray.length + "]");
for (int i = 0; i < DevArray.length; i++) {
if (i != 0) {
System.out.print(", ");
}
System.out.print(DevArray[i]);
}
System.out.println();
}
}

Output :

C:\Program Files\Java\jdk1.6.0_18\bin>javac DevClass.java

C:\Program Files\Java\jdk1.6.0_18\bin>java DevClass
Sorted array: [length: 12]
-9, -7, -3, -2, 0, 1, 2, 3, 4, 5, 6, 8
2 is found at index 6

fill() Method Example


import java.util.*;

public class FillDemo {
	public static void main(String args[]) {
		int DevArray[] = new int[6];
		Arrays.fill(DevArray, 100);
		for (int i = 0, n = DevArray.length; i < n; i++) {
			System.out.println(DevArray[i]);
		}
		System.out.println();
		Arrays.fill(DevArray, 3, 6, 50);
		for (int i = 0, n = DevArray.length; i < n; i++) {
			System.out.println(DevArray[i]);
		}
	}
}

Output :

C:\Program Files\Java\jdk1.6.0_18\bin>javac FillDemo .java

C:\Program Files\Java\jdk1.6.0_18\bin>java FillDemo 
100
100
100
100
100
100

100
100
100
50
50
50

Download Source Code

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