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Adding code for chapters 1-12
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‎ch01/Goodbye.java

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/**
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* Example program that demonstrates print vs println.
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*/
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public class Goodbye {
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/**
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* Prints a greeting.
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*/
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public static void main(String[] args) {
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System.out.print("Goodbye, "); // note the space
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System.out.println("cruel world");
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}
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}

‎ch01/Hello.java

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public class Hello {
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public static void main(String[] args) {
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// generate some simple output
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System.out.println("Hello, World!");
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}
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}

‎ch02/Variables.java

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/**
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* Examples from Chapter 2.
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*/
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public class Variables {
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public static void main(String[] args) {
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String message;
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int x;
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String firstName;
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String lastName;
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int hour, minute;
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message = "Hello!"; // give message the value "Hello!"
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hour = 10; // assign the value 10 to hour
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minute = 59; // set minute to 59
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message = "123"; // legal
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// message = 123; not legal
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String message2 = "Hello!";
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int hour2 = 10;
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int minute2 = 59;
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int a = 5;
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int b = a; // a and b are now equal
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a = 3; // a and b are no longer equal
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String firstLine = "Hello, again!";
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System.out.println(firstLine);
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System.out.print("The value of firstLine is ");
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System.out.println(firstLine);
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System.out.print("The current time is ");
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System.out.print(hour);
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System.out.print(":");
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System.out.print(minute);
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System.out.println(".");
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System.out.print("Number of minutes since midnight: ");
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System.out.println(hour * 60 + minute);
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System.out.print("Fraction of the hour that has passed: ");
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System.out.println(minute / 60);
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System.out.print("Percent of the hour that has passed: ");
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System.out.println(minute * 100 / 60);
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double pi;
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pi = 3.14159;
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double minute3 = 59.0;
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System.out.print("Fraction of the hour that has passed: ");
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System.out.println(minute3 / 60.0);
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double y = 1.0 / 3.0; // correct
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System.out.println(0.1 * 10);
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System.out.println(0.1 + 0.1 + 0.1 + 0.1 + 0.1
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+ 0.1 + 0.1 + 0.1 + 0.1 + 0.1);
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double balance = 123.45; // potential rounding error
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int balance2 = 12345; // total number of cents
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System.out.println(1 + 2 + "Hello");
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// the output is 3Hello
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System.out.println("Hello" + 1 + 2);
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// the output is Hello12
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System.out.println(17 * 3);
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System.out.println(hour * 60 + minute);
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int percentage;
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percentage = (minute * 100) / 60;
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hour = minute + 1; // correct
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// minute + 1 = hour; syntax error
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}
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}

‎ch03/Convert.java

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import java.util.Scanner;
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/**
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* Converts centimeters to feet and inches.
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*/
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public class Convert {
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public static void main(String[] args) {
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double cm;
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int feet, inches, remainder;
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final double centPerInch = 2.54;
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Scanner in = new Scanner(System.in);
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// prompt the user and get the value
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System.out.print("Exactly how many cm? ");
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cm = in.nextDouble();
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// convert and output the result
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inches = (int) (cm / centPerInch);
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feet = inches / 12;
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remainder = inches % 12;
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System.out.printf("%.2f cm = %d ft, %d in\n",
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cm, feet, remainder);
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}
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}

‎ch03/Echo.java

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import java.util.Scanner;
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public class Echo {
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public static void main(String[] args) {
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String line;
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Scanner in = new Scanner(System.in);
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System.out.print("Type something: ");
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line = in.nextLine();
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System.out.println("You said: " + line);
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System.out.print("Type something else: ");
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line = in.nextLine();
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System.out.println("You also said: " + line);
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}
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}

‎ch03/GuessStarter.java

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import java.util.Random;
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/**
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* Starter code for the "guess my number" exercise.
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*/
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public class GuessStarter {
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public static void main(String[] args) {
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// pick a random number
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Random random = new Random();
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int number = random.nextInt(100) + 1;
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System.out.println(number);
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}
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}

‎ch03/Input.java

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/**
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* Examples from Chapter 3.
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*/
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public class Input {
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public static void main(String[] args) {
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System.out.println(System.out);
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System.out.print(4.0 / 3.0);
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System.out.printf("Four thirds = %.3f", 4.0 / 3.0);
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double pi = 3.14159;
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double x = (int) pi * 20.0;
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}
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}

‎ch03/ScannerBug.java

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import java.util.Scanner;
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/**
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* Demonstrates a common problem using Scanner.
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*/
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public class ScannerBug {
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public static void main(String[] args) {
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String name;
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int age;
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Scanner in = new Scanner(System.in);
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System.out.print("What is your name? ");
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name = in.nextLine();
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System.out.print("What is your age? ");
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age = in.nextInt();
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System.out.printf("Hello %s, age %d\n", name, age);
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System.out.print("What is your age? ");
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age = in.nextInt();
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System.out.print("What is your name? ");
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name = in.nextLine();
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System.out.printf("Hello %s, age %d\n", name, age);
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}
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}

‎ch04/Methods.java

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/**
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* Examples from Chapter 4.
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*/
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public class Methods {
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public static void main(String[] args) {
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double root = Math.sqrt(17.0);
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double angle = 1.5;
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double height = Math.sin(angle);
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double degrees = 90;
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double angle2 = degrees / 180.0 * Math.PI;
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double radians = Math.toRadians(180.0);
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double degrees2 = Math.toDegrees(Math.PI);
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long x = Math.round(Math.PI * 20.0);
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double x2 = Math.cos(angle + Math.PI / 2);
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double x3 = Math.exp(Math.log(10.0));
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double x4 = Math.pow(2.0, 10.0);
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}
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}

‎ch04/NewLine.java

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public class NewLine {
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public static void newLine() {
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System.out.println();
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}
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public static void threeLine() {
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newLine();
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newLine();
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newLine();
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}
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public static void main(String[] args) {
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System.out.println("First line.");
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threeLine();
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System.out.println("Second line.");
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}
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}

‎ch04/PrintTime.java

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public class PrintTime {
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public static void printTime(int hour, int minute) {
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System.out.print(hour);
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System.out.print(":");
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System.out.println(minute);
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}
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public static void main(String[] args) {
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int hour = 11;
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int minute = 59;
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printTime(hour, minute);
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}
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}

‎ch04/PrintTwice.java

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public class PrintTwice {
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public static void printTwice(String s) {
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System.out.println(s);
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System.out.println(s);
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}
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public static void main(String[] args) {
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printTwice("Don't make me say this twice!");
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}
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}

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