x yy
x,yy
x yy 123
x,yy,123
第1题:
下列程序将类C15的对象写入文件filetxt,选择正确的语句填入下列程序的横线处。 package ch2; import java.util.*; import java.io.*; class C15______ { public iht a; public void setInt(int newa) { a = newa; } } public class Testl5 { pulibc static void main(String[] args) { C15 bj = new C15(); try { FileOutputStream fos =newFileOutputStream("ch2\\filel5.txt"); ObjectOutputStream os = ObjectOutputStream(fos); Obj.setInt(10); oos.writeObject(obj); oos.close (); fos.close(); } catch(IOException ioe) { ioe.printStackTrace(); } } }
A.implements Runnable
B.implements Sedalizable
C.extends Serializable
D.implements InputStream
第2题:
下列程序在运行时会产生______。 import java.awt.*; public class ex33 { public static void maiN(String[] args) { Image im[] = new Image[4]; System.out.println (im[0] .toString ()); } }
A.NumberFormatExeeption
B.ArittnneticException
C.ArrayIndexOutOfBoundsExcepfion
D.NullPointerException
第3题:
设有如下程序: import java.util.*; public class Sun { public static void main(String args[ ]) { int score; String a; Random r=new Random(); score=r.nextInt(4)+5; switch(score) { case 0: a="E"; break; case 1: a="D"; break; case 2: a="C"; break; case 3: a="B"; break; default: a="A"; } System.out.println(A) ; } } 程序运行的结果是( )。
A.a="A"
B.aa"E" a="A"
C.a="E"
D.a="C"
第4题:
下列程序实现对ZIP文件file.zip的检索,在横线处填入正确的语句 package test; import java.io.*: import java.util.*; import java.util.zip.*; public class Exam { public static void main(String[])args){ try{ FileInputStream fis=new FileInputStream("test/file.zip"); ZipInputStreamzis=new ZipInputStream(fis); ZipEntry en; while ((_____)!=null){ en.getName(); zis.closeEntry(); } zis.close(); } catch(Exception e) { e.printStackTrace(); } } }
A.en = zis.getNextEntry()
B.en = zis.getNextEntry()
C.en = zis.getEntry()
D.zis.getNextEntry()
第5题:
请完善程序(程序文件名:Java_3.java)并进行调试。请在下画线处填入正确内容,然后删除下画线。请勿删除注释行和其他已有的语句内容。
[题目要求]
生成下面左边图形界面,单击图中的New按钮,弹出如右图所示的对话框。
源程序:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_3 {
public static void main(String[] args) {
MulticastFrame. frame=new MulticastFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}
class MulticastFrame. extends JFrame. {
public MulticastFrame() {
setTitle("MulticastTest");
setSize(WIDTH,HEIGHT);
MulticastPanel panel=new MulticastPanel();
Container contentPane=getContentPane();
contentPane.add( (1) );
}
public static final int WIDTH=300;
public static final int HEIGHT=200;
}
class MulticastPanel extends JPanel }
public MulticastPanel() {
JButton newButton=new JButton("New");
add(newButton);
ActionListener newListener=new ActionListener() {
public void actionPerformed(ActionEvent event) {
makeNewFrame();
}
};
newButton.addActionListener(newListener);
closeAllButton=new JButton("Close all");
add(closeAllButton);
}
private void makeNewFrame() {
final BlankFrame. frame=new BlankFrame();
frame.show();
ActionListener closeAllListener=new ActionListener() {
public void actionPerformed(ActionEvent event) {
frame. (2) (); //使窗口隐藏或消除
}
};
closeAllButton.addActionListener( (3) );
}
private JButton closeAllButton;
}
Class BlankFrame. extends JFrame. {
public BlankFrame() {
(4) ++;
setTitle("Frame"+counter);
setSize(WIDTH,HEIGHT);
setLocation(SPACING*counter,SPACING*counter);
}
public static final int WIDTH=200;
public static final int HEIGHT=150;
public static final int SPACING=30;
private static int counter=0;
}
第6题:
下列代码的输出结果是( )。
class parent
{
void printme()
{
System.out.println("parent");
}
}
class child extends parent
{
void printme()
{
System. out.println("child");
}
void printall()
{
super, printme();
this.printme();
printme();
}
}
public class test
{
public static void main(String args[])
{
child myc=new child();
myc.printall();
}
}
A.import java.awt.*;
B.import java.applet.applet;
C.import java.io.*;
D.import java, awt.graphics;
第7题:
请在下列程序的横线处填入正确的语句。 import java.awt.*; import java.awt,event.*; public class ex16 { Frame. f; TextArea ta; Button btn; public static void main(String[] args) { ex16 e = new ex16(); e.m(); } public void m() { f = new Frame("ex16"); ta = new TextArea(); btn = new Button("ok"); btn.addActionListener(new MyAction()); f.add(ta, "Center"); f.add(btn, "South"); f.setSize(100, 100); f.setVisible (true); } class MyAction implements ActionListener { ______ { System. out.println (ta. getText ()); } } }
A.static void actionPcrformcd(AcfionEvent e)
B.public void action(ActionEwent e)
C.public actionPerformed(ActionEvent e)
D.public void actionPerformed(ActionEvent e)
第8题:
如下两个源程序文件,分别编译后,运行Example.class文件,运行结果为______。
AB.java文件代码如下;
package test;
public class AB
{
int a=60;
public void show()
{
System.out.println(”a=”+a);
}
Example.java文件代码如下:
import test.AB;
class Example
{
public static void main(String args[])
{
AB bj=new AB();
obj.show();
}
}
第9题:
本题的功能是获取鼠标在窗口中的位置。当鼠标移进窗口中,就会实时显示鼠标在窗口中的相对位置,比如显示为"鼠标的当前位置:X:Y"(其中,X为横坐标,Y为纵坐标)。
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class java2
{
public static void main(String[]args)
{
MouseFrame. frame=new MouseFrame();
frame.setDefaultCloseoperation(JFrame.EXIT_
0N CLOSE);
frame.show();
}
}
class MouseFrame. extends JFrame
{
public MouseFrame()
{
setTitle("java2");
setSize(WIDTH,HEIGHT);
MousePanel panel=new MousePanel();
Container contentPane=getContentPane();
contentPane.add(panel);
}
public static final int WIDTH = 300;
public static final int HEIGHT=200;
}
class MousePanel extends JPanel
{
public MousePanel()
{
addMouseListener(new MouseHandler());
addMouseMotionListener(new MouseMotionHan-
dler());
}
public void paintComponent(Graphics g)
(
super.paintComponent(g);
String text="鼠标指针位置:"+mousex+":"
+mousey;
g.drawString(text,10,10);
}
private int mousex,mousey;
private class MouseMotionHandler {
public void mouseMoved(MouseEvent event)
{
mousex=event.getX();
mousey=event.getY();
repaint();
}
public void mouseDragged(MouseEvent event)
{
mousex=event.getX();
mousey=event.getY();
repaint();
}
}
private class MouseHandler
{
public void mousePressed(MouseEvent eveat)
{mousex=event.getX();
mousey=event.getY();
}
}
}
第10题:
以下程序调试结果为:
public class Test {
int m=5;
public void some(int x) {
m=x;
}
public static void main(String args []) {
new Demo().some(7);
}
}
class Demo extends Test {
int m=8;
public void some(int x) {
super.some(x);
System.out.println(m);
}
}
A.5
B.8
C.7
D.无任何输出
E.编译错误