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Java Program to find keys from both the Linked HashMap

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
public class Demo {
	public static void main(String[] args) {
		Map<String, String>map1 = new LinkedHashMap<String, String>();
		map1.put("1", "Jim");
		map1.put("2", "David");
		map1.put("3", "Tom");
		map1.put("4", "Sam");
		map1.put("5", "Steve");
		Map<String, String>map2 = new LinkedHashMap<String, String>();
		map2.put("6", "Katie");
		map2.put("7", "John");
		map2.put("8", "Kane");
		map2.put("9", "Chris");
		List<String>list = new ArrayList<String>();
		list.addAll(map1.keySet());
		list.addAll(map2.keySet());
		System.out.println("Keys...");
		for (String str: list) {
			System.out.println(str);
		}
	}
}

Java Program to Toss a Coin

import java.util.Random;
class Toss {
	public String chanceFunc() {
		Random r = new Random();
		int chance = r.nextInt(2);
		if (chance == 1) {
		return"tails";
		} else {
		return"heads";
		}
	}
}
public class Demo {
	public static void main(String[] args) {
		Toss t = new Toss();
		int heads = 0;
		int tails = 0;
		int chances = 10;
		for (int i = 1; i<= chances; i++) {
		if (t.chanceFunc().equals("tails")) {
		tails++;
		  } else {
		heads++;
		  }
		}
		System.out.println("Chances = " + chances);
		System.out.println("Heads: " + heads);
		System.out.println("Tails: " + tails);
		}
}

Java Program to get random letters

import java.util.Random;
public class Demo {
	static Random randNum = new Random();
	public static void main(String args[]) {
		System.out.println("Lowercase random letters...");
		for (int i = 0; i< 5; i++) {
			System.out.println("" + "abcdefghijklmnopqrstuvwxyz".toCharArray()[randNum.nextInt("abcdefghijklmnopqrstuvwxyz".toCharArray().length)]);
		}
		System.out.println("Uppercase random letters...");
		for (int i = 0; i< 5; i++) {
			System.out.println("" + "ABCDEFGHIJKLMNOPQRSTUVWZYZ".toCharArray()[randNum.nextInt("ABCDEFGHIJKLMNOPQRSTUVWZYZ".toCharArray().length)]);
		}
	}
}

Generate random booleans in Java

import java.util.Random;
public class Demo {
	public static final void main(String... args) {
		Random randNum = new Random();
		System.out.println("Displaying random Booleans...");
		for (int i = 1; i<= 5; ++i) {
		boolean randomRes = randNum.nextBoolean();
		System.out.println(randomRes);
		}
	}
}

Convert Float array list to float array in Java

import java.util.ArrayList;
public class Demo {
	public static void main(String[] args) {
		ArrayList<Float>arrList = new ArrayList<Float>();
		arrList.add(5.2f);
		arrList.add(10.3f);
		arrList.add(15.3f);
		arrList.add(20.4f);
		arrList.add(25.2f);
		arrList.add(30.6f);
		arrList.add(45.3f);
		arrList.add(50.9f);
		final float[] arr = new float[arrList.size()];
		int index = 0;
		for (final Float value: arrList) {
			arr[index++] = value;
		}
		System.out.println("Elements of float array...");
		for (Float i: arr) {
			System.out.println(i);
		}
	}
}

Generate large random numbers in Java

import java.math.BigInteger;
import java.util.Random;
public class Demo {
	public static void main(String... a) {
		int max = 10;
		Random randNum = new Random();
		byte[] b = new byte[max];
		randNum.nextBytes(b);
		// BigInteger type
		BigInteger bigInt = new BigInteger(b);
		System.out.println("Very large random number = "+bigInt);
	}
}

Program to iterate over a List using Java 8 Lambda

import java.util.ArrayList;
import java.util.List;
public class Demo {
	public static void main(String[] args) {
		ArrayList<String>arrayList = new ArrayList<String>();
		arrayList.add("100");
		arrayList.add("200");
		arrayList.add("300");
		arrayList.add("400");
		arrayList.add("500");
		arrayList.add("600");
		arrayList.add("700");
		arrayList.add("800");
		arrayList.add("900");
		arrayList.add("1000");
		System.out.println("ArrayList...");
		for (String s: arrayList)
			System.out.println(s);
			ArrayList<String>list = arrayList;
			System.out.println("Iterating...");
			list.stream().forEach(elem -> System.out.println(elem));
	}
}

Test if a List is an Unmodifable List in Java

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
public class Demo {
	public static void main(String[] args) {
		List<Integer>list = new LinkedList<Integer>();
		list.add(10);
		list.add(20);
		list.add(30);
		list.add(40);
		list.add(50);
		List<Integer>unmodifiable = Collections.unmodifiableList(list);
		if (unmodifiable.getClass().getName().contains("UnmodifiableList"))
			System.out.println("This is an UnmodifiableList" );
		else
			System.out.println("This is not an UnmodifiableList" );
	}
}

Shuffle a List in Java

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class Demo {
public static void main(String args[]) {
    Integer[] strArray = new Integer[] { 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 };
    List<Integer>list = Arrays.asList(strArray);
    System.out.println("List = "+list);
    Collections.shuffle(list);
    System.out.println("Shuffled List = "+list);
  }
}

Java Program to create Duration from seconds

import java.time.Duration;
public class Demo {
	public static void main(String[] args) {
		Duration duration = Duration.ofDays(10);
		Duration duration1 = Duration.ofHours(10);
		Duration duration2 = Duration.ofMillis(10);
		Duration duration3 = Duration.ofMinutes(10);
		System.out.println("Seconds in 10 days = "+duration.getSeconds());
		System.out.println("Seconds in 10 hours = "+duration1.getSeconds());
		System.out.println("Seconds in 10 milliseconds = "+duration2.getSeconds());
		System.out.println("Seconds in 10 minutes = "+duration3.getSeconds());
	}
}

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