无法从另一个类打印变量？
[英]can't print variable from another class?
问题描述
I am trying to write contents of a variable from another class. 
我正在尝试从另一个类编写变量的内容。
code where the variable is set, note that there is a print statement that lets me know how many calories the variable is holding at the moment, this works just the way it should it's not 0 at least 设置变量的代码，请注意，有一条打印语句使我知道该变量当前持有多少卡路里，它的工作方式至少应不为0
edit
import java.util.*; //importing utilities use the Scanner
public class food extends products{
//variable declaration
private String[] foodName;
private String[] drinkName;
private String[] NoNo;
public int calories;
public int protz;
public int carbz;
public int fatz;
Scanner input = new Scanner(System.in);//importing scanner and creating an object for it
Interface inte = new Interface(); //creating an object interface
caloriesmain m = new caloriesmain(); // creating a main class object to enable the exit to main menu
public void setFood(){
this.name = "Food"; //overriding name variable inherited from class products to "Food"
this.description = "NB!The amount of nutrition is based on the raw weight of product with skin where applicable";//overriding description variable inherited from class products to a descriptive message
System.out.println(name); // printing the header of the Menu
//Storing items in to the array
String[] foodNA = {"1. Chicken", "2.Eggs", "3. Turkey", "4. Pork", "5. Beef", "6. Fish", "7, Rice"}; //storing food names
Integer[] nutriCalories = {230, 84, 194, 149, 150, 82, 111};//storing calories for each food name
Integer[] nutriProtein = {43, 6, 29, 28, 25, 18, 3};//Storing protein amount
Integer[] nutriCarb = {0, 1, 0, 0, 0, 0, 23};//storing carbohydrate amount
Integer[] nutriFat = {5, 6, 8, 3, 4, 1, 1};//storing fat amount
this.foodName = foodNA;
//converting arrays to arraylists( reason for conversion: could not find a way to index a regular array)
List<Integer> intList = Arrays.asList(nutriCalories);
List<Integer> intList2 = Arrays.asList(nutriProtein);
List<Integer> intList3 = Arrays.asList(nutriCarb);
List<Integer> intList4 = Arrays.asList(nutriFat);
System.out.println(description); //displaying an informative message
System.out.println(Arrays.toString(getFood()));//displaying all of the stored food names
System.out.println("8. Display Current intake");
System.out.println("9. Next");
int option = input.nextInt();//calling scanner to store an integer entered by the user in option variable
if (option == 1){ //if user chooses option number 1
int cals = intList.get(0); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(0); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(0); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(0); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 2){ //if user chooses option number 1
int cals = intList.get(1); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(1); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(1); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(1); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 3){ //if user chooses option number 1
int cals = intList.get(2); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(2); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(2); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(2); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 4){ //if user chooses option number 1
int cals = intList.get(3); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(3); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(3); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(3); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 5){ //if user chooses option number 1
int cals = intList.get(4); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(4); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(4); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(4); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 6){ //if user chooses option number 1
int cals = intList.get(5); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(5); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(5); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(5); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if (option == 7){ //if user chooses option number 1
int cals = intList.get(6); //stores the amount of calories that is on index 0 in the arraylist
int prots = intList2.get(6); //stores the amount of protein that is on index 0 in the arraylist
int carbs = intList3.get(6); //stores the amount of carbohydrates that is on index 0 in the arraylist
int fats = intList4.get(6); //stores the amount of fat that is on index 0 in the arraylist
System.out.println("+" + cals);//print out how many calories did this product add to the total amount
calories +=cals;//adds calories to the current amount
protz +=prots;//adds protein to the current amount
carbz +=carbs;//adds carbohydrates to the current amount
fatz +=fats; //adds fat to the current amount
System.out.println("total: " + calories);//displays the running total of the calories after each choice
setFood(); //displays the list again if user needs to add more than one product
}
else if(option == 8){
System.out.println("Current intake \n Calories:" + calories + "\nProtein: " + protz + "\nCarbohydrates: " + carbz + "\nFats :" +fatz);
setFood();
}
else if(option==9){// if user chooses 9 then the next method is called
setDrink();
}
}
public String[] getFood(){
return foodName;
}
public void setDrink(){
this.name = "Drinks";
System.out.println(name);
String[] drinkNA = {"1. Coffee", "2.Tea", "3. Ionised Drinks", "4. Soda", "5. Cola", "6. Diet Coke", "7. Milk"};
Integer[] nutriCalories = {3, 3, 80, 11, 12, 0, 42};
Integer[] nutriProtein = {0, 0, 0, 0, 0, 0, 4};
Integer[] nutriCarb = {0, 1, 1, 3, 3, 0, 5};
Integer[] nutriFat = {0, 0, 0, 0, 0, 0, 1};
this.drinkName = drinkNA;
List<Integer> intList = Arrays.asList(nutriCalories);
List<Integer> intList2 = Arrays.asList(nutriProtein);
List<Integer> intList3 = Arrays.asList(nutriCarb);
List<Integer> intList4 = Arrays.asList(nutriFat);
System.out.println(Arrays.toString(getDrink()));
System.out.println("8. Display current Intake");
System.out.println("9. Next");
int option = input.nextInt();
if (option == 1){
int cals = intList.get(0);
int prots = intList2.get(0);
int carbs = intList3.get(0);
int fats = intList4.get(0);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 2){
int cals = intList.get(1);
int prots = intList2.get(1);
int carbs = intList3.get(1);
int fats = intList4.get(1);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 3){
int cals = intList.get(2);
int prots = intList2.get(2);
int carbs = intList3.get(2);
int fats = intList4.get(2);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 4){
int cals = intList.get(3);
int prots = intList2.get(3);
int carbs = intList3.get(3);
int fats = intList4.get(3);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 5){
int cals = intList.get(4);
int prots = intList2.get(4);
int carbs = intList3.get(4);
int fats = intList4.get(4);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 6){
int cals = intList.get(5);
int prots = intList2.get(5);
int carbs = intList3.get(5);
int fats = intList4.get(5);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 7){
int cals = intList.get(6);
int prots = intList2.get(6);
int carbs = intList3.get(6);
int fats = intList4.get(6);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if(option == 8){
System.out.println("Current intake \n Calories:" + calories);
setDrink();
}
else if(option==9){
setNono();
}
}
public String[] getDrink(){
return drinkName;
}
public void setNono(){
this.name = "Restricted products";
this.description = "Alcoholic drinks are measured 'per shot'(30ml),. rest of the food is measured in average serving sizes";
System.out.println(name);
String[] Nono = {"1. Drugs", "2.Whiskey", "3. Vodka", "4. Fries", "5. Hamburger", "6. Pizza"};
Integer[] nutriCalories = {0, 70, 85, 192, 300, 530};
Integer[] nutriProtein = {0, 0, 0, 3, 15, 21};
Integer[] nutriCarb = {0, 0, 0, 25, 35, 55};
Integer[] nutriFat = {0, 0, 0, 10, 11, 25};
this.NoNo = Nono;
List<Integer> intList = Arrays.asList(nutriCalories);
List<Integer> intList2 = Arrays.asList(nutriProtein);
List<Integer> intList3 = Arrays.asList(nutriCarb);
List<Integer> intList4 = Arrays.asList(nutriFat);
System.out.println(description);
System.out.println(Arrays.toString(getNono()));
System.out.println("7. Display current Intake");
System.out.println("8. Exit");
int option = input.nextInt();
if (option == 1){
int cals = intList.get(0);
int prots = intList2.get(0);
int carbs = intList3.get(0);
int fats = intList4.get(0);
System.out.println("Consuming Drugs can harm you and others around you);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setDrink();
}
else if (option == 2){
int cals = intList.get(1);
int prots = intList2.get(1);
int carbs = intList3.get(1);
int fats = intList4.get(1);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setNono();
}
else if (option == 3){
int cals = intList.get(2);
int prots = intList2.get(2);
int carbs = intList3.get(2);
int fats = intList4.get(2);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setNono();
}
else if (option == 4){
int cals = intList.get(3);
int prots = intList2.get(3);
int carbs = intList3.get(3);
int fats = intList4.get(3);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setNono();
}
else if (option == 5){
int cals = intList.get(4);
int prots = intList2.get(4);
int carbs = intList3.get(4);
int fats = intList4.get(4);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setNono();
}
else if (option == 6){
int cals = intList.get(5);
int prots = intList2.get(5);
int carbs = intList3.get(5);
int fats = intList4.get(5);
System.out.println("+" + cals);
calories +=cals;
protz +=prots;
carbz +=carbs;
fatz +=fats;
System.out.println("total: " + calories);
setNono();
}
else if(option == 7){
;
printIntake();
setNono();
}
else if(option==8){
m.main(Nono); //exit to main menu
}
}
public void printIntake(){
System.out.println( calories);
}
public String[] getNono(){
return NoNo;
}
}
the variable that i am trying to write is "calories" it is set from an array, and here is the class where i am trying to write the variable to a text file: 我要写入的变量是“卡路里”，它是从数组中设置的，这是我要在其中将变量写入文本文件的类：
import java.io.*;
import java.util.*;
public class saveLoad extends caloriesmain{
public food FO = new food();
private Scanner x;
public void save(){
System.out.println();
try {
File file = new File("example.txt");
BufferedWriter output = new BufferedWriter(new FileWriter(file));
output.write("calories" + FO.calories);
output.close();
} catch ( IOException e ) {
e.printStackTrace();
}
}
This might be a very wrong way of doing this, i am very new to java, but in my head it should just print it, but it prints 0. 这可能是一种非常错误的方式，我对Java还是很陌生，但是在我看来，它应该只打印它，但是它打印0。
1 个解决方案
解决方案1
0 2013-05-23 00:00:49
How does the saveLoad class know what the food is? saveLoad类如何知道食物是什么？
What you're trying to do will require a constructor 您尝试做的事情将需要一个构造函数
An example of this is: 例如：
import java.io.*;
import java.util.*;
public class SaveLoad extends caloriesmain{
public food FO;
private Scanner x;
public SaveLoad(int calories){
FO= new food(calories);
}
public void save(){
System.out.println();
try {
File file = new File("example.txt");
BufferedWriter output = new BufferedWriter(new FileWriter(file));
output.write("calories" + FO.calories);
output.close();
} catch ( IOException e ) {
e.printStackTrace();
}
}
In the constructor i'm solely guessing the parameters of the food class. 在构造函数中，我只是在猜测food类的参数。
To access this class all you need to do in your main code is create a new instance of it: 要访问此类，您需要在主代码中创建一个新的实例：
SaveLoad save= new SaveLoad(calories);
Then you can call the save function simply by calling this in your main program: 然后，您只需在主程序中调用以下函数即可调用save函数：
save.save();
Alternatively, skip the instantiation of the FO variable: 或者，跳过FO变量的实例化：
import java.io.*;
import java.util.*;
public class SaveLoad extends caloriesmain{
private int calories;
private Scanner x;
public SaveLoad(int calories){
this.calories=calories;
}
//because we've called the calories integer a private variable we need a set method
//it can only be seen from within this class
public void setCalories(int calories){
this.calories=calories
}
public void save(){
System.out.println();
try {
File file = new File("example.txt");
BufferedWriter output = new BufferedWriter(new FileWriter(file));
output.write("calories" + FO.calories);
output.close();
} catch ( IOException e ) {
e.printStackTrace();
}
}
To set different calories instantiate the saveLoad class, and set the calories: 要设置不同的卡路里，请实例化saveLoad类，并设置卡路里：
SaveLoad save= new SaveLoad(calories);
save.setCalories(10);
save.save();
However, whilst this will solve your issue, you need to think about the hierarchy of your class. 但是，尽管这可以解决您的问题，但您需要考虑类的层次结构。
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