Java Program - Action Event. Need Help ...
- Thread starter NhoMt
- Ngày gửi
ZeroCrazy
T.E.T.Я.I.S
- 8/4/06
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Câu 1: chọn "lớp con có thể khai báo biến chưa có trên lớp cha".
Câu 2: viết thử 1 chương trình có biến mang thuộc tính private static rồi thử xem cái nào lỗi.
Mã:
package untitled1;
class Assembly {
/* Instance Variables */
private String name;
private Date today;
private int discount;
//define instance variables named parta, partb, partc
private Part part1;
private Part part2;
private Part part3;
public Assembly(String assemblyName,
int m, int d, int y,
int percentage,
Part partA , Part partB , Part partC ) {
name = assemblyName;
today = new Date(m, d, y);
discount = percentage;
part1 = partA;
part2 = partB;
part3 = partC;
}
public int price() {
/*Return my total un-discounted price in dollars.*/
return part1.price() + part2.price() + part3.price();
}
public int discountedPrice() {
/*Return my discounted price in dollars.*/
double price;
price = price() * (1 - discount);
return (int)(price);
}
public void display() {
System.out.println(name); //display name
System.out.print("\tAssembled on");
System.out.println(today); //display date
System.out.println("\tConsists of");
System.out.print("\t");
this.part1.display();
System.out.print("\t");
this.part2.display();
System.out.print("\t");
this.part3.display();
System.out.print("\tTotal $");
System.out.println(price()); //display price
System.out.print("Discount ");
System.out.print(discount); //display discount
System.out.println("%");
System.out.print("Discounted price $");
System.out.println(discountedPrice()); //display discounted price
}
}
class Part {
private String name;
private int price;
public Part(String partName, int value) {
name = partName;
price = value;
}
public void display() {
/*Display part name*/
System.out.print(name);
System.out.print(" $");
/*Display part price*/
System.out.println(price);
}
public int price() {
return price;
}
}
class Date {
private int month; // 1-12
private int day; // 1-31 based on month
private int year; // any year
//Constructor
public Date(int mn, int dy, int yr) {
month = mn;
day = dy;
year = yr;
}
// Create a String of the form month/day/year
public String toString() {
return month + "/" + day + "/" + year;
}
}
class Test {
//Test the Assembly and Parts classes by creating an assembly and displaying it.
public static void main(String args[]) {
/*Create the 3 part objects part1, part2, part3, create the an assembly object that contains them and
display the assembly. */
//Create object part1 with the values "Engine", 6000
Part partA = new Part("Engine", 6000);
//(Create object part2 with the values"Frame", 7000;
Part partB = new Part("Frame", 7000);
//Create object part3 with the values"Interior", 4000;
Part partC = new Part("Interior", 4000);
//Create object assembly with the values"Automobile", 12,1,2006, 10, part1, part2, part3;
Assembly assembly = new Assembly("Automobile", 12, 1, 2006, 10, partA, partB, partC);
assembly.display();
}
}Lớp lưu trữ các thông tin của sự kiện action.
http://java.sun.com/docs/books/tutorial/java/javaOO/thiskey.html
You can declare a variable in any scope to be final. The value of a final variable cannot change after it has been initialized. Such variables are similar to constants in other programming languages.
To declare a final variable, use the final keyword in the variable declaration before the type.
final int aFinalVar = 0;
The previous statement declares a final variable and initializes it all at once. Subsequent attempts to assign a value to aFinalVar result in a compiler error. You may, if necessary, defer initialization of a final local variable. Simply declare the local variable and initialize it later, as follows.
final int blankfinal;
. . .
blankfinal = 0;
A final local variable that has been declared but not yet initialized is called a blank final. Again, once a final local variable has been initialized, it cannot be set, and any later attempts to assign a value to blankfinal result in a compile-time error.