找不到符号 - 符号 class 日期 - 位置包 java.util

Question

我找不到我的错误。程序说无法找到 class 日期。请帮我找出错误。它是一种继承和多态class。我有 classes：GeometricObject、Circle 和 Rectangle classes。在 GeometricObject class 中，我在私有 java.util.Date dateCreated 中出错。在所有通知错误的程序中，日期都被标记为红色。不知道怎么解决。

package geometricobject;
import java.util.Date;
/**
 *
 * @author kharm
 */
public class GeometricObject {
    private String color = "white";
    private boolean filled;
    private java.util.Date dateCreated;
    
    
    /** Construct a default geometric object */
    public GeometricObject(){
        dateCreated = new Java.util.Date();
    }

    /** COnstruct a geometric object with the specific color and filled value */
    public GeometricObject(String color, boolean filled){
        dateCreated= new java.util.Date();
        this.color = color;
        this.filled = filled;
    }
    
    /** Return color */
    public String getColor(){
        return color;
    }
    
    /** Set a new color */
    public void setColor(String color){
        this.color = color;
    }
    
    /** Return filled. Since filled is boolean
     its getter method is named isFilled */
    public boolean isFilled(){
        return filled;
    }
    
    /** Set a new filled */
    public void setFilled(boolean filled){
        this.filled = filled;
    }
    
    /** Get dateCreated */
    public java.util.Date getDateCreated(){
        return dateCreated;
    }
    
    /** Return a string representation of this object */
    public String toString(){
        return "created on" + dateCreated + "\ncolor: " + color + " and filled: " + filled;
    }

package geometricobject;

/**
 *
 * @author kharm
 */
public class Circle extends GeometricObject {
    private double radius;
    
    public Circle(){
    }
    
    public Circle(double radius){
        this.radius = radius;
    }
    public Circle(double radius, String color, boolean filled){
        this.radius = radius;
        setColor(color);
        setFilled(filled);
    }
    
    /** Return radius
     * @param <error>
     * @return  */
    public double getRadius(){
        return radius;
    }
    
    /** Set a new radius*/
    public void setRadius(double radius){
        this.radius = radius;
    }
    
    /** return area*/
    public double getArea(){
        return radius * radius * Math.PI;
    }
    /** Return diameter*/
    public double getDiameter(){
        return 2 * radius;
    }
    
    /** Return perimeter*/
    public double getPerimeter(){
        return 2 *  radius * Math.PI;
    }
    
    /** Print the Circle info */
    public void printCircle(){
        System.out.println("The circle is created " + getDateCreated() + " and the radius is " + radius);
    }
}

package geometricobject;

/**
 *
 * @author kharm
 */
public class Rectangle extends GeometricObject{
    private double width;
    private double height;
    
    public Rectangle(){
    }
    
    public Rectangle(double width, double height){
        this.width = width;
        this.height = height;
    }
    
    public Rectangle(double width, double height, String color, boolean filled){
        this.width = width;
        this.height = height;
        setColor(color);
        setFilled(filled);
    }
    
    /** Return width */
    public double getWidth(){
        return width;
    }
    
    /** Set a new width*/
    public void setWidth(double width){
        this.width = width;
    }
    
    /** Return height*/
    public double gerHeight(){
        return height;
    }
    
    /** Set a new height*/
    public void setHeight(double height){
        this.height = height;
    }
    
    /** Return area*/
    public double getArea(){
        return width * height;
    }
    
    /** Return perimeter*/
    public double getPerimeter(){
        return 2 * (width + height);
    }
}


package geometricobject;
public class TestCircleRectangle{
    public static void main(String[] args) {
        Circle circle = new Circle(1);
        System.out.println("A Circle " + circle.toString());
        System.out.println("The color is " + circle.getColor());
        System.out.println("The radius is " + circle.getRadius());
        System.out.println("The area is " + circle.getArea());
        System.out.println("The diameter is " + circle.getDiameter());
        
        Rectangle rectangle = new Rectangle(2, 4);
        System.out.println("/nA rectangle " + rectangle.toString());
        System.out.println("The area is " + rectangle.getArea());
        System.out.println("The perimeter is " + rectangle.getPerimeter());        
    }
}

Answer 1

导入日期后无需使用完整路径。

java.util.Date dateCreated; --> Date dateCreated;

将所有java.util.Date更改为日期

我也注意到你用大写写了一些 'J' :/

Answer 2

// The problem was that I wrote java.util.Date with UpperCaseLetter "Java". Thus, 
// please check the spelling.

包几何对象；导入 java.util.Date;

public class GeometricObject {
    private String color = "white";
    private boolean filled;
    private java.util.Date dateCreated;
    
    
    /** Construct a default geometric object */
    public GeometricObject(){
        dateCreated = new java.util.Date();
    }

    /** Construct a geometric object with the specific color and filled value */
    public GeometricObject(String color, boolean filled){
        dateCreated= new java.util.Date();
        this.color = color;
        this.filled = filled;
    }
    
    /** Return color */
    public String getColor(){
        return color;
    }
    
    /** Set a new color */
    public void setColor(String color){
        this.color = color;
    }
    
    /** Return filled. Since filled is boolean
     its getter method is named isFilled */
    public boolean isFilled(){
        return filled;
    }
    
    /** Set a new filled */
    public void setFilled(boolean filled){
        this.filled = filled;
    }
    
    /** Get dateCreated */
    public java.util.Date getDateCreated(){
        return dateCreated;
    }
    
    /** Return a string representation of this object */
    public String toString(){
        return "created on" + dateCreated + "\ncolor: " + color + " and filled: " + filled;
    }

package geometricobject;

public class Circle extends GeometricObject {
    private double radius;
    
    public Circle(){
    }
    
    public Circle(double radius){
        this.radius = radius;
    }
    public Circle(double radius, String color, boolean filled){
        this.radius = radius;
        setColor(color);
        setFilled(filled);
    }
    
    /** Return radius
     * @param <error>
     * @return  */
    public double getRadius(){
        return radius;
    }
    
    /** Set a new radius*/
    public void setRadius(double radius){
        this.radius = radius;
    }
    
    /** return area*/
    public double getArea(){
        return radius * radius * Math.PI;
    }
    /** Return diameter*/
    public double getDiameter(){
        return 2 * radius;
    }
    
    /** Return perimeter*/
    public double getPerimeter(){
        return 2 *  radius * Math.PI;
    }
    
    /** Print the Circle info */
    public void printCircle(){
        System.out.println("The circle is created " + getDateCreated() + " and the radius is " + radius);
    }
}

package geometricobject;

/**
 *
 * @author kharm
 */
public class Rectangle extends GeometricObject{
    private double width;
    private double height;
    
    public Rectangle(){
    }
    
    public Rectangle(double width, double height){
        this.width = width;
        this.height = height;
    }
    
    public Rectangle(double width, double height, String color, boolean filled){
        this.width = width;
        this.height = height;
        setColor(color);
        setFilled(filled);
    }
    
    /** Return width */
    public double getWidth(){
        return width;
    }
    
    /** Set a new width*/
    public void setWidth(double width){
        this.width = width;
    }
    
    /** Return height*/
    public double gerHeight(){
        return height;
    }
    
    /** Set a new height*/
    public void setHeight(double height){
        this.height = height;
    }
    
    /** Return area*/
    public double getArea(){
        return width * height;
    }
    
    /** Return perimeter*/
    public double getPerimeter(){
        return 2 * (width + height);
    }
}


package geometricobject;
public class TestCircleRectangle{
    public static void main(String[] args) {
        Circle circle = new Circle(1);
        System.out.println("A Circle " + circle.toString());
        System.out.println("The color is " + circle.getColor());
        System.out.println("The radius is " + circle.getRadius());
        System.out.println("The area is " + circle.getArea());
        System.out.println("The diameter is " + circle.getDiameter());
        
        Rectangle rectangle = new Rectangle(2, 4);
        System.out.println("/nA rectangle " + rectangle.toString());
        System.out.println("The area is " + rectangle.getArea());
        System.out.println("The perimeter is " + rectangle.getPerimeter());        
    }
}

//输出正确：运行: A Circle 创建于 2 月 20 日星期六 13:35:28 CST 2021 颜色：白色，填充：false 颜色是白色半径为 1.0 面积为 3.141592653589793 直径为2.0

2 月 20 日星期六创建的矩形 13:35:28 CST 2021 颜色：白色，填充：false 面积8.0 周长是12.0

找不到符号 - 符号 class 日期 - 位置包 java.util

cannot find symbol - symbol class date - Location package java.util

java

compiler-errors

java.util.date

cannot-find-symbol