Archives: Array

Java – Check if String Array Contains Value

September 15, 2011 | By Prasanna Sherekar | Post comment

String[] stringArray = new String[] {"AB","BC","CD","AE"};
Arrays.asList(stringArray).contains("XY"); // --> false
Arrays.asList(stringArray).contains("AB"); // --> true
// Note: This doesn't work for arrays of primitives

// Using Java 8 Stream
String[] values = {"AB","BC","CD","AE"};
Arrays.stream(values).anyMatch("s"::equals); // --> false
Arrays.stream(values).anyMatch("CD"::equals); // --> true

String[] stringArray = new String[] {"AB","BC","CD","AE"};

Arrays.asList(stringArray).contains("XY"); // --> false

Arrays.asList(stringArray).contains("AB"); // --> true

// Note: This doesn't work for arrays of primitives

// Using Java 8 Stream

String[] values = {"AB","BC","CD","AE"};

Arrays.stream(values).anyMatch("s"::equals); // --> false

Arrays.stream(values).anyMatch("CD"::equals); // --> true

Java – Bubble Sort Array Example

August 10, 2011 | By Prasanna Sherekar | Post comment

import java.util.Arrays;

/**
 * Algorithm
 * 
 * 1] Compare each pair of adjacent elements from beginning 
 * of an array and, if they are in reversed order, swap them.
 * 	
 * 2] If at least one swap has been done, repeat step 1.
 * 
 */
public class MyBubbleSort {

	private void sortData(int[] data) {
		boolean swapDone = false;
		do {
			swapDone = false;
			for (int i = 0; i < data.length-1; i++) {
				if (data[i] > data[i+1]) {
					swapDone = true;
					int tmp = data[i];
					data[i] = data[i+1];
					data[i+1] = tmp;
				}
			}
		} while (swapDone == true);
	}

	public static void main(String[] args) {
		int[] data = {5,1,12,-5,16};
		System.out.println(Arrays.toString(data));

		new MyBubbleSort().sortData(data);
		System.out.println(Arrays.toString(data));
	}

}

import java.util.Arrays;

/**

* Algorithm

* 1] Compare each pair of adjacent elements from beginning

* of an array and, if they are in reversed order, swap them.

* 2] If at least one swap has been done, repeat step 1.

public class MyBubbleSort {

private void sortData(int[] data) {

boolean swapDone = false;

do {

swapDone = false;

for (int i = 0; i < data.length-1; i++) {

if (data[i] > data[i+1]) {

swapDone = true;

int tmp = data[i];

data[i] = data[i+1];

data[i+1] = tmp;

}

} while (swapDone == true);

}

public static void main(String[] args) {

int[] data = {5,1,12,-5,16};

System.out.println(Arrays.toString(data));

new MyBubbleSort().sortData(data);

System.out.println(Arrays.toString(data));

}

Java – Convert Array to Map using Commons ArrayUtils

October 15, 2010 | By Prasanna Sherekar | Post comment

This example use the Apache Commons lang’s ArrayUtils class to convert a two dimensional array to a Map object.

import java.util.Map;
import org.apache.commons.lang.ArrayUtils;

public class ArrayToMapExample {

    public static void main(String[] args) {
        //
        // A two dimensional array of countries capital.
        //
        String[][] countries = {
            {
                "United States",
                "New York"
            },
            {
                "United Kingdom",
                "London"
            },
            {
                "Netherlands",
                "Amsterdam"
            },
            {
                "Japan",
                "Tokyo"
            },
            {
                "France",
                "Paris"
            }
        };

        //
        // To convert an array to a Map each array elements must
        // be an array with at least two elements where the first
        // element will be the key and the second element will be
        // the value.
        //
        Map countryCapitals = ArrayUtils.toMap(countries);

        System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));
        System.out.println("Capital of France is " + countryCapitals.get("France"));
    }

}

import java.util.Map;

import org.apache.commons.lang.ArrayUtils;

public class ArrayToMapExample {

public static void main(String[] args) {

// A two dimensional array of countries capital.

String[][] countries = {

{

"United States",

"New York"

{

"United Kingdom",

"London"

{

"Netherlands",

"Amsterdam"

{

"Japan",

"Tokyo"

{

"France",

"Paris"

}

};

// To convert an array to a Map each array elements must

// be an array with at least two elements where the first

// element will be the key and the second element will be

// the value.

Map countryCapitals = ArrayUtils.toMap(countries);

System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));

System.out.println("Capital of France is " + countryCapitals.get("France"));

}