Pure Programmer
Blue Matrix

Cluster Map

Lists

L1

This page is under construction. Please come back later.

Lists1.java
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class Lists1 {

	public static void main(String[] args) {
		final int NUM_SQUARES = 5;
		List<Integer> squares = new ArrayList<>();
// Put the squares into the list
		for (int i = 0; i < NUM_SQUARES; ++i) {
			squares.add(i * i);
		}
// Print out the squares from the list
		for (int i = 0; i < squares.size(); ++i) {
			System.out.println(Utils.format("{0:d}^2 = {1:d}", i, squares.get(i)));
		}

		System.out.println(Utils.listToString(squares));
	}
}
Output
$ javac -Xlint Lists1.java $ java -ea Lists1 0^2 = 0 1^2 = 1 2^2 = 4 3^2 = 9 4^2 = 16 [0, 1, 4, 9, 16]
Lists2.java
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class Lists2 {

	public static void main(String[] args) {
		List<Integer> squares = Utils.listFromIntegers(new int[]{0, 1, 4, 9, 16, 25});

// Print out the squares from the list
		for (int i = 0; i < squares.size(); ++i) {
			System.out.println(Utils.format("{0:d}^2 = {1:d}", i, squares.get(i)));
		}
	}
}
Output
$ javac -Xlint Lists2.java $ java -ea Lists2 0^2 = 0 1^2 = 1 2^2 = 4 3^2 = 9 4^2 = 16 5^2 = 25
Lists3.java
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class Lists3 {

	public static void main(String[] args) {
		List<String> names = Utils.listFromStrings(new String[]{"Fred", "Wilma", "Barney", "Betty"});

		for (String name : names) {
			System.out.println(Utils.join("", "Hello, ", name, "!"));
		}

		names = Arrays.asList("Harry", "Ron", "Hermione");
		for (String name : names) {
			System.out.println(Utils.join("", "Hello, ", name, "!"));
		}
	}
}
Output
$ javac -Xlint Lists3.java $ java -ea Lists3 Hello, Fred! Hello, Wilma! Hello, Barney! Hello, Betty! Hello, Harry! Hello, Ron! Hello, Hermione!
Lists4.java
import org.pureprogrammer.Utils;

public class Lists4 {

	public static void main(String[] args) {
// Print out the command line arguments
		for (int i = 1; i <= args.length; ++i) {
			System.out.println(Utils.join("", i, ":", args[i - 1]));
		}
	}
}
Output
$ javac -Xlint Lists4.java $ java -ea Lists4 Fred Barney Wilma Betty 1:Fred 2:Barney 3:Wilma 4:Betty $ javac -Xlint Lists4.java $ java -ea Lists4 10 20 30 40 1:10 2:20 3:30 4:40
Lists5.java
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class Lists5 {

	public static void main(String[] args) {
		List<String> names = Utils.listFromStrings(new String[]{"Fred", "Wilma", "Barney", "Betty"});

// Print out the name based on command line argument 1-4
		for (int i = 1; i <= args.length; ++i) {
			final int x = Utils.stoiWithDefault(args[i - 1], 0);
			System.out.println(Utils.join("", i, ":", names.get(x - 1)));
		}
	}
}
Output
$ javac -Xlint Lists5.java $ java -ea Lists5 1 2 3 4 1:Fred 2:Wilma 3:Barney 4:Betty $ javac -Xlint Lists5.java $ java -ea Lists5 4 3 2 1 1:Betty 2:Barney 3:Wilma 4:Fred $ javac -Xlint Lists5.java $ java -ea Lists5 1 3 1:Fred 2:Barney

Questions

Projects

More ★'s indicate higher difficulty level.

References