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java编程常见类型题

• 使用GUI绘制奥运五环

import javax.swing.*;import java.awt.*;public class Exams3 extends JFrame {       public Exams3(){           // 配置Jfram基本属性         this.setTitle("奥运五环");        this.setSize(500,400);        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        this.setVisible(true);    }    public void paint(Graphics g){           // 创建中间容器绘制图形        JPanel j = new JPanel();        // 调用paint方法绘制        j.paint(g);        j.setOpaque(false);        // 设置颜色        g.setColor(Color.blue);        // 设置位置x、y，图形大小宽、高        g.drawOval(70,70,80,80);        g.setColor(Color.black);        g.drawOval(140,70,80,80);        g.setColor(Color.red);        g.drawOval(210,70,80,80);        g.setColor(Color.yellow);        g.drawOval(105,130,80,80);        g.setColor(Color.green);        g.drawOval(175,130,80,80);        g.drawString("奥运五环",150,250);        g.setColor(Color.blue);    }    public static void main(String[] args) {           SwingUtilities.invokeLater(new Runnable() {               @Override            public void run() {                   new Exams3();            }        });    }}

• 列举邮资可能情况

public class Exam1 {       public static void main(String[] args) {           int sum = 0;        int count = 0;        for (int i=1;i<=9;i++){               System.out.print(i+"张邮票邮资分别是：");            for (int j=0;j<=5;j++){                   for (int k=0;k<=4;k++){                      sum = j*3+k*5;                   count = j+k;                   if (count==i){                          System.out.print(sum+",");                   }                }            }            System.out.println();        }    }}

• 使用Filefilter类实现文件查找

import javax.swing.filechooser.FileFilter;import java.io.File;class JavaFilter extends FileFilter{       @Override    public boolean accept(File f) {         if (f.getName().endsWith(".java")){             return true;      }else {             return false;      }    }    @Override    public String getDescription() {           return null;    }}public class Exam2 {       public static void main(String[] args) {           JavaFilter  javaFilter = new JavaFilter();        File file = new File("G:\\Projects\\IdeaProjects\\JavaExam\\src\\E2018\\");        File[] listFile = file.listFiles();        // 循环遍历数组        for (File files : listFile) {               boolean flag = javaFilter.accept(files);            if(files.isDirectory()) {                   continue;            }else{                   if (flag){                       System.out.println(files.getName());                }            }        }    }}