Java – Convert String to Long

public class StringToLong {

	public static void main(String args[]) {
		String strLong = "2323232";

		//Convert String to long using Long.valueOf(),better because
		//it can cache frequently used long values
		long number = Long.valueOf(strLong);
		System.out.println("String to long conversion using valueOf :" + number);

		//Convert String to long in Java using java.lang.Long object
		strLong ="4444444444444444444";
		Long numberObject = new Long(strLong);
		number = numberObject; //auto boxing will take care of long to Long conversion
		System.out.println("String to long conversion example using Long object: " + number);

		//Convert String to long with Long.parseLong method in Java
		strLong="999999999999999999";
		Long parsedLong = Long.parseLong(strLong) ;
		number = parsedLong; //auto-boxing will convert Long object to primitive long
		System.out.println("String to long conversion using parseLong() method: " + number);

		//Convert String to long using Long.decode() method in Java
		strLong = "-1023454";
		number = Long.decode(strLong);
		System.out.println("String to long conversion using decode() method: " + number);

		//String to long in hexadecimal format
		strLong = "0xFFFF";
		number = Long.decode(strLong);
		System.out.println("String to long example in hex format decode() method: " + number);

		//String to long in octal format
		strLong = "0777";
		number = Long.decode(strLong);
		System.out.println("String to long example in octal format decode() method: " + number);
	}
}

Output:

String to long conversion using valueOf :2323232
String to long conversion example using Long object: 4444444444444444444
String to long conversion using parseLong() method: 999999999999999999
String to long conversion using decode() method: -1023454
String to long example in hex format decode() method: 65535
String to long example in octal format decode() method: 511

Java – Convert Array to Map using Commons ArrayUtils

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"));
	}

}

Java – Convert Array to List

import java.util.*;
import java.io.*;

public class ArrayToCollection {

	public static void main(String args[]) throws IOException {

		BufferedReader in = new BufferedReader
				(new InputStreamReader(System.in));
		System.out.println("How many elements you want to add to the array: ");
		int n = Integer.parseInt(in.readLine());
		String[] name = new String[n];
		for(int i = 0; i < n; i++) {
			name[i] = in.readLine();
		}
		List list = Arrays.asList(name);
		System.out.println();
		for(String li: list) {
			String str = li;
			System.out.print(str + " ");
		}

	}

}

Output:

How many elements you want to add to the array:
red white green

red white green

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