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ConsoleProgram.java
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125 lines (105 loc) · 3.01 KB
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import java.util.Scanner;
public class ConsoleProgram{
private Scanner scanner;
public static void main(String[] args){
// Assume the class name is passed in as the first argument.
if(args.length == 0){
System.out.println("Please provide the name of the main class as an argument.");
return;
}
String mainClassName = args[0];
try{
Class mainClass = Class.forName(mainClassName);
Object obj = mainClass.newInstance();
ConsoleProgram program = (ConsoleProgram)obj;
program.run();
} catch (IllegalAccessException ex) {
System.out.println("Error in program. Make sure you extend ConsoleProgram");
} catch (InstantiationException ex) {
System.out.println("Error in program. Make sure you extend ConsoleProgram");
} catch (ClassNotFoundException ex) {
System.out.println("Error in program. Make sure you extend ConsoleProgram");
}
}
/**
* The run method is overwritten by the subclass. This is the main entry point for
* ConsolePrograms. There is no main method in student programs that extend ConsoleProgram,
* instead they write their application starting like this:
*
* public void run()
* {
* // student code here
* }
*
* The main method of ConsoleProgram calls this run method when it begins.
*/
public void run(){
/* Overridden by subclass */
}
/**
* Constructor for Console program. Create a scanner instance to be used for user input.
*/
public ConsoleProgram(){
scanner = new Scanner(System.in);
}
/**
* This method reads a line of input from the user, given a prompt.
*
* @param prompt A prompt to the user to get input
* @return A String of the user input.
*/
public String readLine(String prompt){
System.out.print(prompt);
return scanner.nextLine();
}
/**
* This method reads a boolean value from the user, asking them for either
* a true or false value. This makes use of the readLine method.
*
* @param prompt A prompt to the user to read a boolean value
* @return A boolean value read from the user.
*/
public boolean readBoolean(String prompt){
while(true){
String input = readLine(prompt);
if(input.equalsIgnoreCase("true")){
return true;
}
if(input.equalsIgnoreCase("false")){
return false;
}
}
}
/**
* This method reads a double value from the user, given a prompt.
*
* @param prompt A prompt to the user to ask for a a double.
* @return A double value read from the user.
*/
public double readDouble(String prompt){
while(true){
String input = readLine(prompt);
try {
double n = Double.valueOf(input).doubleValue();
return n;
} catch (NumberFormatException e){
}
}
}
/**
* This method reads a int value from the user, given a prompt.
*
* @param prompt A prompt to the user to ask for an int
* @return The int value read from the user.
*/
public int readInt(String prompt){
while(true){
String input = readLine(prompt);
try {
int n = Integer.parseInt(input);
return n;
} catch (NumberFormatException e){
}
}
}
}