Develop Reference

How to print Arrays that are inputed by user (java)

I have no idea how to put this...
basically, We are supposed to make an Array. where we input the number of students, their names, and age. after that an output will be displayed. It will show the names and age of a student.
It seems easy for you to look at. but I really need advice on how to shorten the output. like if there is anything I could do to minimize the code and make an infinite number of outputs so that I can input any number of students.
public static void main(String[] args)
{
int ageInput;
Scanner input = new Scanner(System.in);
Scanner input2 = new Scanner(System.in);
System.out.print("Number of Students > ");
int studentValue = input.nextInt();
String[] arraylist = new String[studentValue];
int[] ageinput = new int[studentValue];
char count;
for (count = 0; count < studentValue; count++)
{
System.out.println("Please input a student name and age:");
System.out.println("------------------------------------");
System.out.println("Name: ");
arraylist[count] = input.next();
System.out.println("Age: ");
ageinput[count] = input2.nextInt();
System.out.println(" ");
}
for (String a: arraylist)
{
System.out.println("Student #1");
System.out.println("name: " +arraylist[0]);
System.out.println("age: " +ageinput[0]);
System.out.println("Student #2");
System.out.println("name: " +arraylist[1]);
System.out.println("age: " +ageinput[1]);
System.out.println("Student #3");
System.out.println("name: " +arraylist[2]);
System.out.println("age: " +ageinput[2]);
System.out.println("Student #4");
System.out.println("name: " +arraylist[3]);
System.out.println("age: " +ageinput[3]);
System.out.println("Student #5");
System.out.println("name: " +arraylist[4]);
System.out.println("age: " +ageinput[4]);
}
}
}
I'm not very good at this stuff. soo if you could answer the question I really appreciate it :) Thank you all!

In order to use a loop to print your results i suggest you are using the following code:
for(int i = 0; i <studentValue; i++)
{
System.out.println("Student #" + i + 1);
System.out.println("name: " + arraylist[i]);
System.out.println("age: " + ageinput[i]);
}

Problems using Scanner class

The code works for entering wife's name and age, but fails to print the names of sons, though it displays their ages properly.
import java.util.Scanner;
public class Check2
{
public static void main(String[] args)
{
String wife;
String son1;
String son2;
int wifeAge;
int son1Age;
int son2Age;
Scanner keyboard = new Scanner(System.in);
System.out.println("Wife's name? ");
wife = keyboard.nextLine();
System.out.println("Her age? ");
wifeAge = keyboard.nextInt();
System.out.println();
System.out.println("First son's name? ");
son1 = keyboard.nextLine();
keyboard.nextLine();
System.out.println("His age? ");
son1Age = keyboard.nextInt();
System.out.println();
System.out.println("Second son's name? ");
son2 = keyboard.nextLine();
keyboard.nextLine();
System.out.println("His age? ");
son2Age = keyboard.nextInt();
System.out.println();
keyboard.nextLine();
System.out.println("My wife's name is " + wife + ". She is " +
wifeAge + " years old.\nOur first son is " +
son1 + ". He is " + son1Age + ".\nOur " +
"second son is " + son2 + ". He is " +
son2Age + ".");
}
}

You have the extra keyboard.nextLine(); in the wrong place in your code.
son1 = keyboard.nextLine();
keyboard.nextLine(); // you don't need this here.
son2 = keyboard.nextLine();
keyboard.nextLine(); // nor here
Keep the extra keyboard.nextLine(); line after each keyboard.nextInt(); and your program should run fine.
wifeAge = keyboard.nextInt();
keyboard.nextLine(); // put it here
...
son1Age = keyboard.nextInt();
keyboard.nextLine(); // and here
The nextInt() reads only an integer value and not a new line. If you need to read a new line, you will need to put the keyboard.nextLine(); every time you read integer values from the keyboard.
Hope this helps!

import java.util.Scanner;
public class Check2
{
public static void main(String[] args)
{
String wife;
String son1;
String son2;
int wifeAge;
int son1Age;
int son2Age;
Scanner keyboard = new Scanner(System.in);
System.out.println("Wife's name? ");
wife = keyboard.nextLine();
System.out.println("Her age? ");
wifeAge = keyboard.nextInt();
System.out.println();
System.out.println("First son's name? ");
keyboard.nextLine();
son1 = keyboard.nextLine();
System.out.println("His age? ");
son1Age = keyboard.nextInt();
System.out.println();
System.out.println("Second son's name? ");
keyboard.nextLine();
son2 = keyboard.nextLine();
System.out.println("His age? ");
son2Age = keyboard.nextInt();
System.out.println();
keyboard.nextLine();
System.out.println("My wife's name is " + wife + ". She is " +
wifeAge + " years old.\nOur first son is " +
son1 + ". He is " + son1Age + ".\nOur " +
"second son is " + son2 + ". He is " +
son2Age + ".");
}
}

nextLine() isn't the method you want.
You want to use next() instead, as shown in the following corrected and simplified code. You don't really want to have to manage the newlines, just let the scanner treat all the input as a string of tokens separated by whitespace, and read them in sequence. Use the next() method for inputting strings and nextInt() for inputting integers...
import java.util.Scanner;
public class Check2
{
public static void main(String[] args)
{
String wife;
String son1;
String son2;
int wifeAge;
int son1Age;
int son2Age;
Scanner keyboard = new Scanner(System.in);
System.out.println("Wife's name? ");
wife = keyboard.next();
System.out.println("Her age? ");
wifeAge = keyboard.nextInt();
System.out.println();
System.out.println("First son's name? ");
son1 = keyboard.next();
System.out.println("His age? ");
son1Age = keyboard.nextInt();
System.out.println();
System.out.println("Second son's name? ");
son2 = keyboard.next();
System.out.println("His age? ");
son2Age = keyboard.nextInt();
System.out.println();
System.out.println("My wife's name is " + wife + ". She is " +
wifeAge + " years old.\nOur first son is " +
son1 + ". He is " + son1Age + ".\nOur " +
"second son is " + son2 + ". He is " +
son2Age + ".");
}
}

Array index out of bounds exception 4 [duplicate]

This question already has answers here:
What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?
(26 answers)
Closed 6 years ago.
I keep getting an error when trying to delete or display the users that I've created. Pointing to the line of code where it actually does the deletion or displaying of a certain user. I can't seem to figure out where the error is coming from.
import java.util.*;
public class contactInfo {
public static void main(String[] args) {
String tracker[][] = {
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",},
{" ", " ", " ", " ",}
};
Scanner input = new Scanner(System.in);
int picker = 0;
while (true) {
System.out.print("Please choose an option: \n 1. Add a user \n 2. Delete a user \n 3. Display a user \n 4. Quit ");
picker = input.nextInt();
if (picker == 1) {
addUser(tracker);
} else if (picker == 2) {
deleteUser(tracker);
} else if (picker == 3) {
displayUser(tracker);
} else {
break;
}
}
}
public static String[][] addUser(String[][] add) {
Scanner input = new Scanner(System.in);
System.out.print("Which user is this information for (1 - 10): ");
int user = input.nextInt();
System.out.println(" ");
System.out.print("Enter the users first name: ");
add[user][0] = input.next();
System.out.println(" ");
System.out.print("Enter the users last name: ");
add[user][1] = input.next();
System.out.println(" ");
System.out.print("Enter the users phone number (without dashes): ");
add[user][2] = input.next();
System.out.println(" ");
System.out.print("Enter the users age: ");
add[user][3] = input.next();
System.out.println(" ");
return add;
}
public static String[][] deleteUser(String[][] del) {
Scanner input = new Scanner(System.in);
System.out.print("Which user would you like to delete?: ");
int user = input.nextInt();
for (int i = 0; i < del.length - 1; i++) {
del[user][i] = " ";
}
return del;
}
public static String[][] displayUser(String[][] displ) {
Scanner input = new Scanner(System.in);
System.out.print("Which user would you like to display?: ");
int user = input.nextInt();
for (int i = 0; i < displ.length; i++) {
System.out.print(displ[user][i] + " ");
}
return displ;
}
}

Your tracker is a 2-dimensional array. 10 rows of 4 strings each. The problem is this code:
for (int i = 0; i < del.length - 1; i++)
{
del[user][i] = " ";
}
You iterate over the array of 4 strings, but the variable i will go from 0 to 8. What you want is something like:
for (int i = 0; i < del[user].length; i++)
{
del[user][i] = " ";
}

Instead of using displ.length or del.length for you limits, use displ[user].length or del[user].length.

Cannot get a java variable to print

I cannot get the variable adjustedCharge to print out (the text is printed but not the value) I have tried to trace but still cannot get it to print properly. No errors are present either.
import java.util.Scanner;
public class Assignment {
public static void main(String[] args) {
//Declare scanner
Scanner input = new Scanner(System.in);
//Prompt for information
System.out.print("Customer's name:");
String name = input.nextLine();
System.out.print("Customer's address:");
String address = input.nextLine();
System.out.print("Customer's phone number:");
String phone = input.nextLine();
System.out.print("Customer's licence number:");
String licence = input.nextLine();
System.out.print("Customer's credit card number:");
String ccard = input.nextLine();
System.out.print("Credit card expiry date (MM/YYYY):");
String expiry = input.nextLine();
System.out.print("Hire length (in days):");
int hire = Integer.parseInt(input.nextLine());
System.out.print("Make/Model:");
String model = input.nextLine();
System.out.print("Registration of car:");
String rego = input.nextLine();
System.out.print("Hire rate (per day) Either S, M, L:");
char inputRate = input.nextLine().charAt(0);
System.out.print("Total days hired out:");
int totalDays = Integer.parseInt(input.nextLine());
//
double dtotalDays = totalDays;
double surcharge = dtotalDays - hire;
//Daily hire rate / Stage 2
double rate = 0;
if (inputRate == 'S' || inputRate == 's'){
rate = (char) 80.0;
}
if (inputRate == 'M' || inputRate == 'm'){
rate= 110.0;
}
if (inputRate == 'L' || inputRate == 'l'){
rate= 140.0;
}
//Calculate late fees
double penalty = rate * (surcharge * 2);
//Start Stage 3
double dCost=0;
double tCost=0;
StringBuilder dDetail = new StringBuilder("The damage Details are:" + "\n");
StringBuilder tDetail = new StringBuilder("The traffic fines are:" + "\n");
//Setup an exit statement
boolean quit = false;
while (!quit){
System.out.println("<<<Enter one of the following commands:>>>");
System.out.println("A - Damage Repair");
System.out.println("B - Traffic Infringement");
System.out.println("X - Exit Menu");
String schoiceEntry = input.next();
char choiceEntry = schoiceEntry.charAt(0);
//Integer.parseInt(input.nextLine());
double damageCost = 0;
switch (choiceEntry){
case 'A':
case 'a':
input.nextLine();
System.out.println("Enter a description of the damage:");
String damageDetail = input.nextLine();
System.out.println("Enter the damage cost:");
damageCost = input.nextInt();
System.out.print("The damage is: " + damageDetail + "\n");
System.out.print("The damage cost is: " + "$" + damageCost + "\n");
dDetail.append("-" + damageDetail + "\n");
dCost = dCost + damageCost;
System.out.println("----------------------------------");
break;
case 'B':
case 'b':
input.nextLine();
System.out.print("Enter a description of the traffic infringement:");
String trafficDetail = input.nextLine();
System.out.println("Enter the traffic infringement cost:");
double trafficCost = Integer.parseInt(input.nextLine());
tDetail.append("-" + trafficDetail + "\n");
tCost = tCost + trafficCost;
System.out.println("----------------------------------");
break;
case 'X':
case 'x':
quit = true;
System.out.print("***Menu entry has been terminated***" + "\n");
//System.out.printf("Total traffic cost is: %75s\n", "$" + tCost + "\n");
//System.out.printf("Total Damage cost is: %77s\n", "$" + dCost + "\n");
//System.out.printf(tDetail + "\n");
//System.out.print(dDetail + "\n");
break;
default:
System.out.print("Please enter either a valid menu selection (A, B, or X):" + "\n");
break;
}
}
double dhire = hire;
double charge = dhire*rate;
double adjustedCharge = charge + penalty;
//Print summary
System.out.println("---------------------------------------------"+
"------------------------------------------------------\n" +
"***CUSTOMER DETAILS:***\n");
System.out.printf("Name: %93s\n", name);
System.out.printf("Address: %90s\n", address);
System.out.printf("Phone Number: %85s\n", phone);
System.out.printf("Licence Number: %83s\n", licence);
System.out.printf("Credit Card Number: %79s\n", ccard);
System.out.printf("Credit Card Expiry: %79s\n", expiry);
System.out.println( "\n***CAR HIRE DETAILS:***\n");
System.out.printf("Make/Model: %87s\n", model);
System.out.printf("Registration Number: %78s\n", rego);
System.out.printf("Hire Length (days): %79s\n", model);
System.out.printf("Daily Hire Rate: %82s\n", rate);
System.out.printf("Basic Hire Charge: %80s\n\n", charge);
System.out.printf("Days hired: %87s\n", totalDays);
if (totalDays == hire){
System.out.printf("Late Return Surcharge: %76s\n", "$0.00");
}
if (totalDays > hire){
System.out.printf("Late Return Surcharge: %76s\n", + penalty);
}
System.out.printf("Adjusted Hire Charge: %77s\n", "\n", "$" + adjustedCharge + "\n");
System.out.print(dDetail + "\n");
System.out.printf("Total damage cost is: %78" + "s\n", "$" + dCost + "\n");
System.out.printf(tDetail + "\n");
System.out.printf("Total traffic fines incurred: %70s\n", "$" + tCost + "\n");
System.out.printf("Final hire charge: %79s\n", "$" + (adjustedCharge + dCost + tCost));
}
}

I just changed the way you printed out the adjustedCharge so you can still use printf
System.out.printf("Adjusted Hire Charge: %77s","$");
System.out.printf("%.1f",adjustedCharge);
System.out.printf("\n");
With printf you need to format the value you're printing and in this case, because you're trying to print a double, you'll need to format it with %f
I also noticed that my previous answer messed up the spacing you had for the rest of your output. So here's the fixed solution! Just change up the spacing to however you'd like

Or you can
use
Pass two arguments to printf
System.out.printf("Adjusted Hire Charge: %77s\n", "$" + adjustedCharge + "\n")
instead of
System.out.printf("Adjusted Hire Charge: %77s\n", "\n", "$" + adjustedCharge + "\n");

How to fix the column alignment in my code?

This is just for the sake of formality/neatness. Backlash t (\t), which is all I know, doesn't seem to work very well. Here's my code:
import java.util.Scanner;
public class RegisterStudent {
public static void register() {
System.out.println("----------------------------------------");
System.out.println("Student Class Card Evaluation System");
System.out.println("----------------------------------------");
System.out.println("Personal Data");
Scanner input = new Scanner(System.in);
System.out.print("\tEnter student no.: ");
long studNo = input.nextLong();
System.out.print("\tEnter first name: ");
String fName = input.next();
System.out.print("\tEnter last name: ");
String lName = input.next();
System.out.print("\tEnter course: ");
String course = input.next();
System.out.println();
System.out.println("----------------------------------------");
System.out.println("Subject: Computer Programming 2");
System.out.println("----------------------------------------");
System.out.println();
System.out.print("\tPrelim Grade: ");
double pg = input.nextDouble();
System.out.print("\tMidterm Grade: ");
double mg = input.nextDouble();
System.out.print("\tPrefinal Grade: ");
double pfg = input.nextDouble();
System.out.print("\tFinal Grade: ");
double fg = input.nextDouble();
System.out.println();
System.out.println("----------------------------------------");
double gwa = (pg + mg + pfg + fg)/4;
System.out.println();
System.out.println("Student Evaluated successfully...");
System.out.println("Viewing Report...");
System.out.println();
System.out.println("--------------------------------------------------------------------------------------------");
System.out.println("ID No.\t\t" + "LASTNAME\t\t" + "FIRSTNAME\t\t" + "COURSE\t\t"
+ "PG\t\t" + "MG\t\t" + "PFG\t\t" + "FG\t\t" + "GWA");
System.out.println("--------------------------------------------------------------------------------------------");
System.out.println(studNo + "\t\t" + lName + "\t\t" + fName + "\t\t" + course + "\t\t"
+ pg + "\t\t" + mg + "\t\t" + pfg + "\t\t" + fg + "\t\t" + gwa);
The output should look something like this:
Everything that the user will input should be properly aligned. Please help me fix my program, thanks guys!
My current output is this:
You see it's not properly aligned

Since this is homework, here are a couple of hints:
The printf method on a PrintWriter or PrintStream classes can do alignment. So can String.format and the Formatter class.
Don't use TAB characters (i.e. '\t') for alignment in simple text output if you want the alignment to be portable. Different OSes have different ideas on the "width" of a TAB.

The number of tabs you need on each line of input will be determined by the length of the prompt text which appears first on the line i.e. the shorter the prompt, the more tabs required. Simple trial and error should sort out your output to give you the required result.