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计算机自考java 实践课
2，求50以内的质数问题。
public class Demo2
{
public static void main(String[]args)
{
int i,j;
for(i=2;i=50;i++)
{
for(j=2;j=i/2;j++)
if(j%i==0)break;
if(ji/2)
System.out.println(i+"是质数");
}
}
}
3，排*问题[注意别把for后面加了;号]。
import javax.swing.*;
public class Demo15
{
public static void main(String[]args)
{
int n,j,k,space;
String result=(String)JOptionPane.showInputDialog(null,"请输入一个整数","输入对话框",JOptionPane.PLAIN_MESSAGE,null,null,null);
n=Integer.parseInt(result);
space=40;
for(j=0;j=n;j++,space-=2)
{
for(int i=0;ispace;i++)
System.out.print(" ");
for(k=1;k=2*j+1;k++)
System.out.print(" *");
System.out.print("n");
}
space+=4;
for(j=n-1;j=0;j--,space+=2)
{
for(int i=0;ispace;i++)
System.out.print(" ");
for(k=1;k=2*j+1;k++)
System.out.print(" *");
System.out.print("n");
}
}
}
5，红绿按钮题：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Demo
{
public static void main(String[]args)
{
ButtonDemo myButtonGUI=new ButtonDemo();
myButtonGUI.setVisible(true);
}
}
class ButtonDemo extends JFrame implements ActionListener
{
public static final int Width=200;
public static final int Height=250;
ButtonDemo()
{
setSize(Width,Height);
setTitle("按钮事件样例");
Container conPane=getContentPane();
conPane.setBackground(Color.YELLOW);
conPane.setLayout(new FlowLayout());
JButton redBut=new JButton("Red");
redBut.addActionListener(this);
conPane.add(redBut);
JButton greenBut=new JButton("Green");
greenBut.addActionListener(this);
conPane.add(greenBut);
}
public void acionPerformed(ActionEvent e)
{
Container conPane=getContentPane();
if(e.getActionCommand().equals("Red"))
conPane.setBackground(Color.RED);
else if(e.getActionCommand().equals("Green"))
conPane.setBackground(Color.GREEN);
else {}
}
}
7，按钮激活文本，显示文本[注意方法是小写，类是大写，所有字母都不能错]
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Demo7 extends Applet implements KeyListener
{
//setSize(400,500);
int count=0;
Button button=new Button();
TextArea text=new TextArea(5,20);
public void init()
{
button.addKeyListener(this);
add(button);
add(text);
}
public void keyPressed(KeyEvent e)
{
int t=e.getKeyCode();
if(t=KeyEvent.VK_At=KeyEvent.VK_Z)
{
text.append((char)t+" "); count++;
if(count%10==0) text.append("n");
}
}
public void keyTyped(KeyEvent e){}
public void keyReleased(KeyEvent e){}
}
8，单击按钮显示单击的次数，
import javax.swing.*;
import java.awt.event.*;
import java.applet.*;
public class Demo8 extends Applet implements ActionListener
{
int n=0;
JButton button=new JButton("单击按钮可以显示点击的次数");
public void init()
{
setSize(800,600);
button.addActionListener(this);
button.setSize(34,3);
add(button);
}
public void actionPerformed(ActionEvent e)
{
n++;
button.setText(n+" ");
}
}
9，画五角星。
import java.awt.*;
import javax.swing.*;
class MyPanel extends JPanel
{
public void paintComponent(Graphics g)
{
int r=100;
int x1=100;
int x2=(int)(r*(1-Math.cos((18*Math.PI)/180)));
int x3=(int)(r*(1+Math.cos((18*Math.PI)/180)));
int x4=(int)(r*(1-Math.cos((54*Math.PI)/180)));
int x5=(int)(r*(1+Math.cos((54*Math.PI)/180)));
int y1=0;
int y2=(int)(r*(1-Math.sin((18*Math.PI)/180)));
int y3=(int)(r*(1-Math.sin((18*Math.PI)/180)));
int y4=(int)(r*(1+Math.sin((54*Math.PI)/180)));
int y5=(int)(r*(1+Math.sin((54*Math.PI)/180)));
g.setColor(Color.RED);
g.drawOval(0,0,200,200);
g.drawLine(x1,y1,x4,y4);
g.drawLine(x1,y1,x5,y5);
g.drawLine(x2,y2,x3,y3);
g.drawLine(x2,y2,x5,y5);
g.drawLine(x3,y3,x4,y4);
}
}
public class Demo9 extends JFrame
{
Demo9()
{
super("Demo9");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().add(new MyPanel());
setSize(800,600);
setVisible(true);
}
public static void main(String[]args)
{
new Demo9();
}
}
java实验类设计学生类,每个学生有两门课程,统计10个学生的各自总分和平均分
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class StudentTest{
private static ListStudent list = new ArrayListStudent();
private static int num = 0;
public static void main(String[] args){
init(); //初始化学生信息
print(); //显示学生信息
}
private static void print(){
System.out.println("================================================================");
System.out.println(" 姓名 科目1 科目2 总分 平均分 ");
System.out.println("================================================================");
for(Student stu : list){
System.out.println(" "+ stu.getName()+" "+stu.getClass1()+" "+stu.getClass2()+" "+(stu.getClass1()+stu.getClass2())+" "+(int)(stu.getClass1()+stu.getClass2())/2+" ");
System.out.println("----------------------------------------------------------------");
}
}
private static void init(){
try{
Scanner scanner = new Scanner(System.in);
System.out.println("请输入学生信息：");
System.out.print("学生数：");
num = scanner.nextInt();
for(int i=0;inum;i++){
System.out.println("总的"+num+"人，第"+(i+1)+"个人的信息");
System.out.print("姓名：");
String name = scanner.nextLine();
name = scanner.nextLine();
System.out.print("第一门课成绩：");
int class1 = scanner.nextInt();
System.out.print("第二门课成绩：");
int class2 = scanner.nextInt();
Student stu = new Student(name,class1,class2);
list.add(stu);
}
}catch(Exception e){
e.printStackTrace();
}
}
}
class Student{
private String name;
private int class1;
private int class2;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getClass1() {
return class1;
}
public void setClass1(int class1) {
this.class1 = class1;
}
public int getClass2() {
return class2;
}
public void setClass2(int class2) {
this.class2 = class2;
}
public Student(String name, int class1, int class2) {
this.name = name;
this.class1 = class1;
this.class2 = class2;
}
}
java课程设计（证件照应用，包括人脸识别，裁剪，压缩等的）求实验总结
public BufferedImage replaceWithWhiteColor(BufferedImage bi) {
int[] rgb = new int[3];
int width = bi.getWidth();
int height = bi.getHeight();
int minx = bi.getMinX();
int miny = bi.getMinY();
/**
* 遍历图片的像素，为处理图片上的杂色，所以要把指定像素上的颜色换成目标白色 用二层循环遍历长和宽上的每个像素
*/
int hitCount = 0;
for (int i = minx; i width-1; i++) {
for (int j = miny; j height; j++) {
/**
* 得到指定像素（i,j)上的RGB值，
*/
int pixel = bi.getRGB(i, j);
int pixelNext = bi.getRGB(i+1, j);
/**
* 分别进行位操作得到 r g b上的值
*/
rgb[0] = (pixel 0xff0000) 16;
rgb[1] = (pixel 0xff00) 8;
rgb[2] = (pixel 0xff);
/**
* 进行换色操作，我这里是要换成白底，那么就判断图片中rgb值是否在范围内的像素
*/
//经过不断尝试，RGB数值相互间相差15以内的都基本上是灰色，
//对以身份证来说特别是介于73到78之间，还有大于100的部分RGB值都是干扰色，将它们一次性转变成白色
if ((Math.abs(rgb[0] - rgb[1]) 15)
(Math.abs(rgb[0] - rgb[2]) 15)
(Math.abs(rgb[1] - rgb[2]) 15)
(((rgb[0] 73) (rgb[0] 78))||(rgb[0] 100))) {
//进行换色操作,0xffffff是白色
bi.setRGB(i, j, 0xffffff);
}
}
}