A.高性能
B.跨平台
C.面向对象
D.有类库
第1题
applet的运行过程要经历4个步骤,其中哪个不是运行步骤?
A.浏览器加载指定URL中的HTML文件
B.浏览器显示HTML文件
C.浏览器加载HTML文件中指定的applet类
D.浏览器中的Java运行环境运行该applet
第2题
为实现多线程之间的通信,需要使用下列哪种流才合适?
A.Filterstream
B.Filestream
C.Randomaccessstream
D.Pipedstream
第3题
执行完以下代码int[]x=newint[25];后,以下哪项说明是正确的
A.x[24]为0
B.x[24]未定义
C.x[25]为0
D.x[0]为空
第4题
【题目描述】
欲构造ArrayList类的一个实例,此类继承了List接口,下列( )是正确的。A.ArrayListmyList=new Object();
B.List myList=new ArrayList();
C.ArrayList myList=new List();
D.List myList=new List();
【我提交的答案】: B |
【参考答案与解析】: 正确答案:A |
【我的疑问】
为什么不是B
第5题
【题目描述】
若有定义int a=2;则执行完语句a+=a-=a*a;后,a的值是( )。A.0
B.4
C.8
D.-4
【我提交的答案】: B |
【参考答案与解析】: 正确答案:D |
【我的疑问】
这题是怎么运算
第6题
盘和时针、分针,通过文本框分别设定“时”和“分”,表盘中的时针和分针就会指到对应的位置上。
import java.awt.*;
import java.awt.event*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.event.*;
public class java3
{
public static void main(String[]args)
{
TextTestFrame. frame=new TextTestFrame():
frame.setDefauhCloseOperation(JFrame.EXIT_
0N_CLOSE);
frame.show();
}
}
class TextTestFrame. extends JFrame
{
public TextTestFrame()
{
setTitle("java3"):
setSize(DEFAULT_WIDTH,DEFAULT_
HElGHT);
Container contentPane=getContentPane();
DocumentListener listener=new DoeumentListen-
er();
JPanel panel=new JPanel();
hourField=new JTextField("12",3);
panel.add(hourField);
hourField.getDocument().addDocumentListener
(this);
minuteField=new JTextField("00",3):
panel.add(minuteField);
minuteField.getDocument().addDocumentListener
(listener);
contentPane.add(panel,BorderLayout.S()UTH);
clock=new ClockPanel();
contentPane.add(clock,BorderLayout.CEN-
TER);
}
public void setClock()
{
try
{
int hours
=Integer.parseInt(hourField.getText().trim
()):
int minutes
=Integer.parseInt(minuteField.getText().trim
());
clock.setTime(hours,minutes);
}
catch(NumberFormatExcepfion e){}
}
public static final int DEFAULT_WIDTH=300;
public static final int DEFAULT_HEIGHT
=300;
private J TextField hourField;
private JTextField minuteField;
private ClockPanel clock;
private class clockFieldListener extends Docu-
mentListener
{
public void insertUpdate(DocumentEvent e){ set-
Clock();}
public void removeUpdate(DocumentEvent e){
setClock();}
public void changedUpdate(DocumentEvent e){}
}
}
class ClockPanel extends JPanel
{
pubhc void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphies2D g2=(Graphics2D)g;
Ellipse2D circle
=new Ellipse2D.Double(0,0,2* RADIUS,2
*RADIUS);
g2.draw(circle);
double hourAngle
=Math.toRadians(90-360*minutes/(12
*60));
drawHand(92,hourAngle,HOUR_HAND_
LENGTH);
double minuteAngle
=Math.toRadians(90-360*minutes/60);
drawHand(g2,minuteAngle,MINUTE_HAND_
LENGTH):
}
punic void drawHand(Graphics2D g2,
double angle,double handLength)
{
Point2D end=new Point2D.Double(
RADIUS+handLength*Math.cos(angle),
RADIUS-handLength*Math.sin(angle));
Point2D center=new Point2D.Double(RADIUS,
RADIUS):
g2.draw(new Line2D.Double(center,end));
}
public void setTime(int h,int m)
{
minutes=h*60+m;
repaint();
}
private double minutes=0;
private double RADIUS=100;
private double MINUTE_HAND_LENGTH=
0.8*RADIUS;
private double HOUR_HAND_LENGTH=0.6
*RADIUS:
}
第7题
下面程序中,在主窗口单击鼠标后,就会生成一个新
窗口。
import java.awt.*;
import java.awt.event.*;
public class java3 extends Frame{
java3(){
super("java3");
addNotify();
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
Insets insets=getInsets();
setSize(insets.left+insets.right+150,
insets.top+insets.bottom+150);
this.addMouseListener(MouseEventHandler());
}
class MouseEventHandler implements MouseAda-
pter{
public void mousePresse(MouseEvent evt){
Rectangle bounds=getBounds();
int x=evt.getX()+bounds.x;
int y=evt.getY()十bounds.y;
java3 m=newjava3();
m.setLocation(x,y);
m.show();
}
}
static public void main(String[]args){
(new java3()).show();
}
}
第8题
ext color control”,窗口的底部还有一个复选按钮“Disable changes”。在“Sample text”面板中有一个带有字符串的文本框,而在“Text color control”面板中有三个按钮:“Black”、“Red”和“Green”,并且每个按钮上都有一个对应颜色的圆。单击任意按钮,文本框中的文本变成对应的颜色,如果选中“Disable changes”复选项,则三个颜色按钮变为不可用,如果取消选中复选项,则三个按钮变为可用。
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class java3 extends JFrame{
private JPanel upper,middle,lower;
private JTextField text;
private JButton black,red,green;
private JCheckBox disable;
public java3(String titleText){
super(titleText);
addWindowListener(new WindowAdapter(){
public void
windowClosing(WindowEvent e){
System.exit(0);
}
}
);
upper=new JPanel();
upper.setBorder(BorderFactory.ereateTitledBor-
der("Sample text"));
upper.setlayout(new BorderLayout());
text=new JTextField("Change the color of this
text"):
upper.add(text,BorderLayout.CENTER);
middle=new JPanel();
middle.setBorder(BorderFactory.createTitledBor-
der("Text color control"));
middle.setLayout(new FlowLayout(FlowLayout.
CENTER)):
black=new JButton("Black",new ColorIcon
(Color.black));
black.addActionListener( new ButtonListener
(Color.black));
middle.add(black);
red=new JButton("Red",new ColorIcon(Col-
or.red));
red.addActionListener(new ButtonListener(Col-
or.red));
middle.add(red);
green=new JButton("Green",new ColorIcon
(Color.green));
green.addActionListener(new ButtonListener
(Color.green));
middle.add(green);
lower=new JPanel();
lower.setLayout(new FlowLayout(FlowLayout.
RIGHT));
disable=new JCheckBox("Disable changes"):
disable.addItemListener(new ItemListener()(
public void itemStateChanged(ItemEvent e){
boolean enabled
=(e.getStateChange()
= =ItemEvent.DESELECTED):
black.setEnabled(enabled);
red.setEnabled(enabled);
green.setEnabled(enabled);
}
}
);
lower.add(disable);
Container cp=getContentPane();
cp.add(upper,BorderLayout.NORTH);
cp.add(middle,BorderLayout.CENTER);
cp.add(10wer,BorderLayout.SoUTH);
pack();
setVisible(true);
}
class ButtonListener extends ActionListener{
private Color c;
public ButtonListener(Color c){
this.c=c;
}
public void actionPerformed(ActionEvent e){
text.setForeground(c);
}
}
class ColorIcon implements Icon{
private Color c;
private static final int DIAMETER=10;
public ColorIcon(Color c){
c=c;
}
public void paintlcon(Component cp,Graphics g,
int x,int y){
g.setColor(c);
g.fillOval(X,y,DIAMETER,DIAMETER);
g.setColor(Color.black);
g.drawOval(x,y,DIAMETER,DIAMETER);
}
public int getlconHeight(){
return DIAMETER;
}
public int getlconWidth(){
return DIAMETER;
}
}
public static void main(String[]args){
new java3("advance");
}
}
第9题
、一运算符和小数点,程序顶部的文本框用来显示操作数以及结果。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class java2{
public static void main(String[]args){
try{
UIManager.setLookAndFeel(UIManager.getSys-
temLookAndFeelClassName());
}
catch(Exception e){}
JFrame. frame=new CalculatorFrame();
frame.show();
}
}
class CalculatorPanel extends JPanel implements Ac-
tionListener{
private JTextField display;
private JButton btn;
private double arg=0;
private String p="=";
private boolean start=true;
public CalculatorPanel(){
setLayout(new BorderLayout());
display=new JTextField("0");
display.setEditable(false);
add(display,"North");
JPanel P=new JPanel();
P.setLayout(new GridLayout(4,4));
String buttons="789/456*123-0.=+":
for(int i=0;i<;buttons.length();i++){
btn=new JButton(buttons.substring(i,i+
1));
P.add(btn);
;
}
add(P,"Center");
}
public void actionPerformed(ActionEvent evt){
String s=evt.getActionCommand();
if(‘0 ‘<;=s.charAt(0)&&s.charAt(O)<;=‘
9‘‖ s.equals("-")){
if(start)display.setText(s):
else display.setText(display.getText()+s);
start=false;
}
else{
if(start){
if(s.equals("-")){
display.setText(s):
start=false;
}
else p=S;
}
else(
double x=
calculate(x);
op=S:
start=true;
}
}
}
public void calculate(double n){
if(op.equals("+"))arg+=n:
else if(op.equals("-"))arg-=n;
else if(op.equals("*"))arg*=n;
else if(op.equals("/"))arg/=n;
else if(op.equals("="))arg=n;
display.setText(""+arg);
}
}
class CalculatorFrame. extends JFrame{
public CalculatorFrame(){
setTitle("java2");
setSize(220,180);
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
Container contentPane=getContentPane();
contentPane.add(new CalculatorPanel());
}
}
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