java中抽象类的输出有问题
我试图打印抽象类中方法的值。有一个switch语句调用抽象方法，还有一个语句打印数组中的项。我尝试了案例1（添加新圆圈）和案例6（显示形状） 案例6中的说明符或call语句可能有问题java中抽象类的输出有问题,java,abstract-class,Java,Abstract Class,我试图打印抽象类中方法的值。有一个switch语句调用抽象方法，还有一个语句打印数组中的项。我尝试了案例1（添加新圆圈）和案例6（显示形状） 案例6中的说明符或call语句可能有问题 package lab8; import java.util.Scanner; public class test { public static void main(String args[]) { // DATA Shape[] shapes = new Shape[10]; int
package lab8;
import java.util.Scanner;
public class test {
public static void main(String args[])
{
// DATA
Shape[] shapes = new Shape[10];
int nextIDNumber = 1;
boolean exit = false;
int selection;
Scanner input = new Scanner(System.in);
int id;
double x, y;
double base = 0, height = 0, width = 0, radius = 0, scaleFactor;
boolean found = false;
// ALGORITHM
// loop until user exits
do
{
// display menu
System.out.println("1 Add a new circle");
System.out.println("2 Add a new rectangle");
System.out.println("3 Add a new right triangle");
System.out.println("4 Delete a shape");
System.out.println("5 Delete all shape");
System.out.println("6 Display all shapes");
System.out.println("7 Move a shape");
System.out.println("8 Enter a scale factor");
System.out.println("9 Scale all shapes");
System.out.println("10 Exit program");
// get user choice
selection = input.nextInt();
while (selection < 1 || selection > 10)
{
System.out.println("Please enter valid choice");
selection = input.nextInt();
}
// switch on selection
switch(selection)
{
case 1:
// ADD NEW CIRCLE
System.out.println("Enter radius for your circle: ");
radius = input.nextDouble();
// get size from user (one variable)
// get location from user (two variables)
System.out.println("Enter x location for your circle: ");
x = input.nextDouble();
System.out.println("Enter y location for your circle: ");
y = input.nextDouble();
// set found to false
found = false;
for(int i = 0; i < shapes.length; i++) {
if (shapes[i] == null) {
shapes[i] = new Circle (nextIDNumber++, x, y, radius);
found = true;
break;
}
}
if(!found) {
System.out.println("Array is full. ERROR");
}
break;
// loop through array
// if this is not a valid object
// create new Circle object and assign to current array element
// set found to true
// break out of loop
// if not found, give error message
// break out of switch statement
case 2:
// ADD NEW RECTANGLE
// get size from user (two variables)
System.out.println("Enter height of rectagle: ");
height = input.nextDouble();
System.out.println("Enter width of rectagle: ");
width = input.nextDouble();
// get location from user (two variables)
System.out.println("Enter x location for your rectangle: ");
x = input.nextDouble();
System.out.println("Enter y location for your rectangle: ");
y = input.nextDouble();
// set found to false
found = false;
for (int i = 0; i< shapes.length;i++) {
if(shapes[i] != null) {
shapes[i] = new Rectangle(nextIDNumber++, x,y, height, width);
found = true;
break;
}
}
if(!found) {
System.out.println("ERROR");
}
break;
case 3:
// ADD NEW RIGHT TRIANGLE
// get size from user (two variables)
System.out.println("Enter the base: ");
base = input.nextDouble();
while (base <= 0)
{
System.out.println("Invalid number, please enter positive number");
base = input.nextDouble();
}
System.out.println("Enter the height");
height = input.nextDouble();
while (height <= 0)
{
System.out.println("Invalid number, please enter positive number");
height = input.nextDouble();
}
// get location from user (two variables)
System.out.println("Enter X location");
x = input.nextDouble();
while (x < 0)
{
System.out.println("Invalid number, please enter positive number or zero");
x = input.nextDouble();
}
System.out.println("Enter Y location");
y = input.nextInt();
while (y < 0)
{
System.out.println("Invalid number, please enter positive number or zero");
y = input.nextDouble();
}
// set found to false
found = false;
// loop through array
for (int i = 0; i < shapes.length; i++)
{
// if this is not a valid object
if (shapes[i] == null)
{
// create new RightTriangle object and assign to current array element
shapes[i] = new RightTriangle(nextIDNumber++, x, y, base, height);
// set found to true
found = true;
// break out of loop
break;
}
}
// if not found, give error message
if (!found)
{
System.out.println("No more room");
}
// break out of switch statement
break;
case 4:
// DELETE ONE SHAPE
// get id number to delete
System.out.println("Enter ID of shape to be deleted: ");
id = input.nextInt();
found = false;
for (int i = 0; i< shapes.length; i++) {
if (id == shapes[i].getID() && shapes[i] != null) {
shapes[i] = null;
found = true;
break;
}
}
if (!found) {
System.out.println("Shape not found.");
}
break;
case 5:
// DELETE ALL SHAPES
System.out.println("Are you sure you want to delete all shapes? 1] YES 2] NO : ");
int choice = input.nextInt();
if(choice == 1) {
for (int i= 0; i<shapes.length; i++) {
if(shapes[i]!=null) {
shapes[i] = null;
}
}
}
break;
case 6:
// DISPLAY ALL SHAPES
// print header
System.out.println("Here are our shapes");
System.out.printf("%10s %10s %10s %10s %10s\n", "ID", "X", "Y", "AREA", "PERIMETER");
for (int i = 0; i<shapes.length;i++) {
if (shapes[i] != null) {
System.out.printf("%10d %10.2f %10.2f %10.2f %10f\n", shapes[i].getID(),shapes[i].getxLoc(),shapes[i].getyLoc(),shapes[i].getArea(),
shapes[i].getPerimiter() );
}
}
break;
case 7:
// MOVE A SHAPE
System.out.println("Enter the ID of shape:");
id = input.nextInt();
System.out.println("Enter X location of shape:");
x = input.nextDouble();
System.out.println("Enter Y location of shape:");
y = input.nextDouble();
found = false;
for(int i =0; i<shapes.length;i++) {
if(id == shapes[i].getID() && shapes[i] != null) {
shapes[i].setxLoc(x);
shapes[i].setxLoc(y);
found = true;
break;
}
}
if (!found) {
System.out.println("Not found.");
}
break;
case 8:
// ENTER A SCALE FACTOR
System.out.println("Enter scale factor: ");
scaleFactor = input.nextDouble();
Shape.setScaleFactor(scaleFactor);
break;
// get scale factor
// call SetScaleFactor to set the new scale factor
// break out of switch statement
case 9:
// SCALE ALL SHAPES
for(int i =0;i<shapes.length;i++) {
if (shapes[i] != null) {
shapes[i].scaleShape();
}
}
// loop through array
// if this is a valid object
// call ScaleShape
// break out of switch statement
break;
case 10:
System.out.println("Do you want to exit? \n1] YES\n2] NO");
int user = input.nextInt();
if(user == 1) {
System.out.println("Thank you!");
exit = true;
}
break;
// EXIT PROGRAM
// confirm user wants to exit
// set variable to break out of loop
// break out of switch statement
}
} while (!exit);
}
构造函数中的赋值错误，因此与形状关联的值均为零。您需要将其切换。此构造函数：
// one constructor
public Shape(int i, double x, double y) {
i = id;
x = xLoc;
y = yLoc;
}
public Shape(int i, double x, double y) {
id = i;
xLoc = x;
yLoc = y;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
radius = r;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
r = radius;
}
public Shape(int i, double x, double y) {
id = i;
xLoc = x;
yLoc = y;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
radius = r;
}
构造函数中的赋值错误，因此与形状关联的值均为零。您需要将其切换。此构造函数：
// one constructor
public Shape(int i, double x, double y) {
i = id;
x = xLoc;
y = yLoc;
}
public Shape(int i, double x, double y) {
id = i;
xLoc = x;
yLoc = y;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
radius = r;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
r = radius;
}
public Shape(int i, double x, double y) {
id = i;
xLoc = x;
yLoc = y;
}
public Circle (int i, double x, double y, double r){
super(i, x, y);
radius = r;
}
你需要学会逻辑地思考当出现问题时你的代码在做什么。在这种情况下，哪里出了问题？哪里应该有有趣的数字，那里只有零。所以你应该像自己一样“这些值从哪里来？”。然后使用可视化调试器查看访问这些值的位置，并查看它们是否为零。如果它们为零，则可以按照这些数字的来源逻辑（代码的输入端）从那里返回。这就是我所做的，而且非常基本。使用调试器！您需要学习逻辑地思考代码出错时所做的事情。在这种情况下有什么问题？应该有有趣的数字，但只有零。因此，您应该像自己一样“这些值来自哪里？”。然后使用可视化调试器查看访问这些值的位置，并查看它们是否为零。如果它们为零，则可以按照这些数字的来源、代码的输入端的逻辑从那里返回。这就是我所做的，而且非常基本。使用调试器！