问答题

下列程序中,给出两个整数2和3,分别求2除以3和2乘以3的结果,要求调用类ex1_1的方法method()来输出相应的结果,请将程序补充完整。程序运行结果如下:
0.6666666666666666
6
public class ex1_1{
public static void main(String[]args) {
int n1=2,n2=3;
ex1_1 obj1_1=new ex1_1();
obj1_1. ______;
}
public void method(int x,int y){
System.out.println(______);
System.out.println(______);
}
}

【参考答案】

method(n1,n2)
(double)x/y
x*y[解析]
本题主要考查Java语言......

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本题程序的功能是计算圆和三角形的面积。通过菜单“选择”可以分别进行圆和三角形面积的计算。单击菜单项“圆面积计算”,窗口中就会显示两个文本框和一个“确定”按钮,在第一个文本框中输入圆的半径,单击“确定”按钮后就可以在第二个文本框中显示圆的面积。单击菜单项“三角形面积计算”,窗口中就会显示4个文本框和一个“确定”按钮,在前三个文本框中分别输入三角形三个边的长度,单击“确定”按钮后,如果三个边的长度不能组成三角形,结果文本框中会给出提示信息,否则显示三角形的面积;如果输入的值不是数值,则会给出提示信息。请将下述程序补充完整(注意:不得改动程序的结构,不得增行或删行)。import java.awt.*;import java.awt.event.*;class circle extends Panel implements AetionListener{double r,area;TextField radius = null,result = null;Button b = null;______;{radius = new TextField(10);result = new TextField(10);b = new Button( 确定 );add (new Label ( 输入半径 ));add (radius);add(new Label( 面积是 ));add(result);add(b);b.addActionListener (this);result,setEnabled (false);}public void actionPerformed(ActionEvent e){try{r = Double.parseDouble (radius.getText ());area =Math.PI*r*r;result,setText ( +area);}catch (Exception ee){radius.setText ( 请输入数字字符 );}}}class triangle extends Panel implements ActionListener{double a = 0,b = 0,c = 0,area;TextField border a = new TextField(6) ;TextField border b = new TextField(6) ;TextField border c = new TextField(6) ;Result = new TextField(24);Button button = new Button( 确定 );triangle (){add(new Label( 输入三边的长度 ));add (border_a);add (border_b);add (border_c);add(new Label( 面积是: ));add (result);add (button);button,addActionListener (this);result.setEnabled(false);}public void actionPerformed(ActionEvent e){try{a = Double.parseDouble{border_a.getText());b = Double.parseDouble(border_b.getText());c = Double.parseDouble(border_c.getText());if(a+b>c&&a+c>b&&c+b>a){double p = (a+b+c) 2;area = Math.sqrt(p*(p-a)*(p-b)*(p-c));result.setText( + area);}else{result.setText ( 您输入的数字不能形成三角形 );}}catch(Exception ee){result.setText ( 请输入数字字符 );}}}class Win ______ implements ActionListener{MenuBar bar = null;Menu menu = null;MenuItem item1,item2;circle circle;triangle trangle;Win(){bar = new MenuBar(); menu = new Menu( 选择 );setSize(300,200);item1 = new MenuItem( 圆面积计算 );item2 = new MenuItem( 三角形面积计算 );menu.add(item1);menu.add(item2);bar.add(menu);setMenuBar(bar);circle = new circle();trangle = new triangle();item1.addActionListener(this);item2.addActionListener(this);setVisible(true);}public void actionPerformed(ActionEvent e){if (e.getSource() == item1){removeAll();add(circle, Center );validate();}elseif(e.getSource() == item2){removeAll ();add (trangle, Center );validate ();}}public class advance{public static void main (String args[]){Win win = new Win();win.setTitle ( advance );win.setBounds (100,100,700,300);win.setVisible (true);win.addWindowListener (______){public void windowClosing(WindowEvent e){System.exit (0);}});}}
问答题
请完成以下程序,首先由一个类Example2_3实现Serializable接口,并有三个成员变量,分别为int型、double型和String型,可以用toString的方法显示这三个成员变量。在main方法中创建这个Example2_3的持久对象,根据用户在命令行输入的三个参数来设定其中成员变量的值。然后,将这个对象写入名为TheSerial.data的文件,并显示成员变量。最后从文件TheSerial.data中读出三个成员变量并显示出来。注意:请勿改动main()主方法和其他已有语句内容,仅在横线处填入适当语句。import java.io.*;class TheSerial implements Serializable{private int intValue;private double doubleValue;private String string;TheSerial(){intValue = 123;doubleValue = 12.34;string = Serialize Test ;}public void setDouble(double d){doubleValue = d;}public void setInt(int i){intValue = i;}public void setString(String s){string = s;}public String toString(){return( int= +intValue+ double= +doubleValue+ string= +string);}}public class Example2_3{public static void main(String argv[]){TheSerial e1 = new TheSerial();TheSerial e2;try{e1.setInt(Integer.parseInt(argv[0]));e1.setDouble(Double.parseDouble(argv[1]));e1.setString[argv[2]);}catch(Exception e){e1.setString(e.getMessage{));}System.out.println(e1);try{FileOutputStream oS = new FileOutputStream( TheSerial.data );ObjectOutputStream oIS = new ObjectOutputStream(oS);______;}catch(IOException ioException){System.out.println(ioException.getMessage());}try{FileInputStream iS = new FileInputStream( TheSerial. data );ObjectInputStream oIS = new ObjectInputStream(iS);______System.out.println(e2);}catch(IOException ioException){System.out.println(ioException.getMessage());}catch(ClassNotFoundException cnfException){System.out.println(cnfException.getMessage());}}}