superexam.java

Java程序设计实用教程源代码 本书源代码按章分别放置在不同的文件夹中,所有程序均在JDK1.6环境下编译运行正常,除了第13章需要建立ODBC数据源之外,其他程序只要有Java运行环境即可直接运行

package useSuper;
class Pen {
  String color;
  int length;
  public Pen() { //默认构造函数，没有任何参数
  }
  Pen(String color) { //只有一个字符型参数color的构造函数
    this.color = color;
  }
  Pen(int length) { //只有一个数值型参数length的构造函数
    this.length = length;
  }
  Pen(String color, int length) { //有两个参数color和length的构造函数
    this.color = color;
    this.length = length;
  }
  void display() {  
    System.out.println("Color is " + color);
    System.out.println("length is " + length);
  }
}
class myPen extends Pen {
  int weight;
  public myPen() {
  }
  myPen(String color, int weight) {
    super(color); //调用父类的构造函数Pen(String color)
    this.weight = weight;
  }
  myPen(int length, int weight) {
    super(length); //调用父类的构造函数Pen(int length)
    this.weight = weight;
  }
  myPen(String color, int length, int weight) {
    super(color, length); //调用父类的构造函数Pen(String color,int length)
    this.weight = weight;
  }
  void display() {  
    super.display();
    System.out.println("weight is " + weight);
  }
}
public class superExam {
  public static void main(String args[]) {
    myPen p = new myPen("Blue",13,56);
    p.display();
  }
}