//异常示例1public class ExceptionDemo1 {public static void main(String args[]) {int a = 0;if(a==0) {System.out.println("除数为零");}else {System.out.println(5 / a);}}}

//异常示例2
import java.io.*;public class ExceptionDemo1 {public static void main(String args[]) throws IOException {FileInputStream fis=new FileInputStream("text.txt");//JVM自动生成异常对象int b;while((b=fis.read())!=-1){System.out.print(b);}fis.close();}
}

package stackTrace;import java.util.*;/*** A program that displays a trace feature of a recursive method call.* @version 1.01 2004-05-10* @author Cay Horstmann*/
public class StackTraceTest
{/*** Computes the factorial of a number* @param n a non-negative integer* @return n! = 1 * 2 * . . . * n*/public static int factorial(int n){System.out.println("factorial(" + n + "):");Throwable t = new Throwable();StackTraceElement[] frames = t.getStackTrace();for (StackTraceElement f : frames)System.out.println(f);int r;if (n <= 1) r = 1;else r = n * factorial(n - 1);System.out.println("return " + r);return r;}public static void main(String[] args){Scanner in = new Scanner(System.in);System.out.print("Enter n: ");int n = in.nextInt();factorial(n);}
}

//积极处理
import java.io.*;
class ExceptionDemo1 {public static void main (String args[]){File fis=new File("身份证号.txt");try{FileReader fr = new FileReader(fis);BufferedReader br = new BufferedReader(fr);try {String s, s2 = new String();while ((s = br.readLine()) != null) {s2 += s + "\n ";}br.close();System.out.println(s2);} catch (IOException e) {// TODO Auto-generated catch block
             e.printStackTrace();}} catch (FileNotFoundException e) {// TODO Auto-generated catch block
         e.printStackTrace();}}
}

//消极处理方式import java.io.*;
class ExceptionDemo1 {public static void main (String args[]) throws  IOException{File fis=new File("身份证号.txt");FileReader fr = new FileReader(fis);BufferedReader br = new BufferedReader(fr);String s, s2 = new String();while ((s = br.readLine()) != null) {s2 += s + "\n ";}br.close();System.out.println(s2);}
}

package ID;public class Person implements Comparable<Person> {
private String name;
private String ID;
private int age;
private String sex;
private String birthplace;public String getname() {
return name;
}
public void setname(String name) {
this.name = name;
}
public String getID() {
return ID;
}
public void setID(String ID) {
this.ID= ID;
}
public int getage() {return age;
}
public void setage(int age) {this.age= age;
}
public String getsex() {
return sex;
}
public void setsex(String sex) {
this.sex= sex;
}
public String getbirthplace() {
return birthplace;
}
public void setbirthplace(String birthplace) {
this.birthplace= birthplace;
}public int compareTo(Person o) {return this.name.compareTo(o.getname());
}
public String toString() {return  name+"\t"+sex+"\t"+age+"\t"+ID+"\t"+birthplace+"\n";
}}
package ID;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;public class Main{private static ArrayList<Person> Personlist;public static void main(String[] args) {Personlist = new ArrayList<>();Scanner scanner = new Scanner(System.in);File file = new File("C:\\mydirectory\\身份证号.txt");try {FileInputStream fis = new FileInputStream(file);BufferedReader in = new BufferedReader(new InputStreamReader(fis));String temp = null;while ((temp = in.readLine()) != null) {Scanner linescanner = new Scanner(temp);linescanner.useDelimiter(" ");    String name = linescanner.next();String ID = linescanner.next();String sex = linescanner.next();String age = linescanner.next();String place =linescanner.nextLine();Person Person = new Person();Person.setname(name);Person.setID(ID);Person.setsex(sex);int a = Integer.parseInt(age);Person.setage(a);Person.setbirthplace(place);Personlist.add(Person);}} catch (FileNotFoundException e) {System.out.println("查找不到信息");e.printStackTrace();} catch (IOException e) {System.out.println("信息读取有误");e.printStackTrace();}boolean isTrue = true;while (isTrue) {System.out.println("1:按姓名字典序输出人员信息");System.out.println("2:查询最大年龄与最小年龄人员信息");System.out.println("3：按省份找同乡");System.out.println("4:输入你的年龄,查询年龄与你最近人的信息");System.out.println("5：退出");int nextInt = scanner.nextInt();   switch (nextInt) {case 1:Collections.sort(Personlist);System.out.println(Personlist.toString());break;case 2:                 int max=0,min=100;int j,k1 = 0,k2=0;for(int i=1;i<Personlist.size();i++){j=Personlist.get(i).getage();if(j>max){max=j; k1=i;}if(j<min){min=j; k2=i;}}  System.out.println("年龄最大："+Personlist.get(k1));System.out.println("年龄最小："+Personlist.get(k2));break;case 3:System.out.println("省份?");String find = scanner.next();        String place=find.substring(0,3);String place2=find.substring(0,3);for (int i = 0; i <Personlist.size(); i++) {if(Personlist.get(i).getbirthplace().substring(1,4).equals(place)) System.out.println("同乡 "+Personlist.get(i));} break;case 4:System.out.println("年龄：");int yourage = scanner.nextInt();int near=agenear(yourage);int d_value=yourage-Personlist.get(near).getage();System.out.println(""+Personlist.get(near));break;case 5:isTrue = false;System.out.println("欢迎使用!");break;default:System.out.println("输入有误");}}}public static int agenear(int age) {int j=0,min=53,d_value=0,k=0;for (int i = 0; i < Personlist.size(); i++){d_value=Personlist.get(i).getage()-age;if(d_value<0) d_value=-d_value; if (d_value<min) {min=d_value;k=i;}}    return k;}}

public class math {private int a;private int b;public static int  add(int a,int b){return a+b;}public static int   reduce(int a,int b){return a-b;}public static int   multiplication(int a,int b){return a*b;}public static int   division(int a,int b){if(b!=0)return a/b;else return 0;}
}

import java.io.*;
import java.io.PrintWriter;
import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner in = new Scanner(System.in);PrintWriter out = null;try {out = new PrintWriter("text.txt");} catch (FileNotFoundException e) {// TODO Auto-generated catch block
            e.printStackTrace();}int sum = 0;for (int i = 1; i <=10; i++) {int a = (int)  Math.round(Math.random() * 100);int b = (int) Math.round(Math.random() * 100);int m = (int) Math.round(Math.random()*4);switch(m){case 1:System.out.println(i+": "+a+"/"+b+"=");while(b==0){  b = (int) Math.round(Math.random() * 100); }int c1 = in.nextInt();if (c1 == a / b) {System.out.println("恭喜答案正确");sum += 10;}else {System.out.println("抱歉，答案错误");}break;case 2:System.out.println(i+": "+a+"*"+b+"=");int c2 = in.nextInt();if (c2 == a * b) {System.out.println("恭喜答案正确");sum += 10;                   }else {System.out.println("抱歉，答案错误");}break;case 3:System.out.println(i+": "+a+"+"+b+"=");int c3 = in.nextInt();out.println(a+"+"+b+"="+c3);if (c3 == a + b) {System.out.println("恭喜答案正确");sum += 10;}else {System.out.println("抱歉，答案错误");}break ;case 4:System.out.println(i+": "+a+"-"+b+"=");int c4 = in.nextInt();if (c4 == a - b) {System.out.println("恭喜答案正确");sum += 10;}else {System.out.println("抱歉，答案错误");}break ;} }System.out.println("成绩"+sum);}
}

//断言程序示例public class AssertDemo {public static void main(String[] args) {       test1(-5);test2(-3);}private static void test1(int a){assert a > 0;System.out.println(a);}private static void test2(int a){assert a > 0 : "something goes wrong here, a cannot be less than 0";System.out.println(a);}}

package logging;import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.logging.*;
import javax.swing.*;/*** A modification of the image viewer program that logs various events.* @version 1.03 2015-08-20* @author Cay Horstmann*/public class LoggingImageViewer
{public static void main(String[] args){if (System.getProperty("java.util.logging.config.class") == null&& System.getProperty("java.util.logging.config.file") == null){try{Logger.getLogger("com.horstmann.corejava").setLevel(Level.ALL);final int LOG_ROTATION_COUNT = 10;Handler handler = new FileHandler("%h/LoggingImageViewer.log", 0, LOG_ROTATION_COUNT);Logger.getLogger("com.horstmann.corejava").addHandler(handler);}catch (IOException e){Logger.getLogger("com.horstmann.corejava").log(Level.SEVERE,"Can't create log file handler", e);}}EventQueue.invokeLater(() ->{Handler windowHandler = new WindowHandler();windowHandler.setLevel(Level.ALL);Logger.getLogger("com.horstmann.corejava").addHandler(windowHandler);JFrame frame = new ImageViewerFrame();frame.setTitle("LoggingImageViewer");frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);Logger.getLogger("com.horstmann.corejava").fine("Showing frame");frame.setVisible(true);});}
}/*** The frame that shows the image.*/
class ImageViewerFrame extends JFrame
{private static final int DEFAULT_WIDTH = 300;private static final int DEFAULT_HEIGHT = 400;   private JLabel label;private static Logger logger = Logger.getLogger("com.horstmann.corejava");public ImageViewerFrame(){logger.entering("ImageViewerFrame", "<init>");      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);// set up menu barJMenuBar menuBar = new JMenuBar();setJMenuBar(menuBar);JMenu menu = new JMenu("File");menuBar.add(menu);JMenuItem openItem = new JMenuItem("Open");menu.add(openItem);openItem.addActionListener(new FileOpenListener());JMenuItem exitItem = new JMenuItem("Exit");menu.add(exitItem);exitItem.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent event){logger.fine("Exiting.");System.exit(0);}});// use a label to display the imageslabel = new JLabel();add(label);logger.exiting("ImageViewerFrame", "<init>");}private class FileOpenListener implements ActionListener{public void actionPerformed(ActionEvent event){logger.entering("ImageViewerFrame.FileOpenListener", "actionPerformed", event);// set up file chooserJFileChooser chooser = new JFileChooser();chooser.setCurrentDirectory(new File("."));// accept all files ending with .gifchooser.setFileFilter(new javax.swing.filechooser.FileFilter(){public boolean accept(File f){return f.getName().toLowerCase().endsWith(".gif") || f.isDirectory();}public String getDescription(){return "GIF Images";}});// show file chooser dialogint r = chooser.showOpenDialog(ImageViewerFrame.this);// if image file accepted, set it as icon of the labelif (r == JFileChooser.APPROVE_OPTION){String name = chooser.getSelectedFile().getPath();logger.log(Level.FINE, "Reading file {0}", name);label.setIcon(new ImageIcon(name));}else logger.fine("File open dialog canceled.");logger.exiting("ImageViewerFrame.FileOpenListener", "actionPerformed");}}
}/*** A handler for displaying log records in a window.*/
class WindowHandler extends StreamHandler
{private JFrame frame;public WindowHandler(){frame = new JFrame();final JTextArea output = new JTextArea();output.setEditable(false);frame.setSize(200, 200);frame.add(new JScrollPane(output));frame.setFocusableWindowState(false);frame.setVisible(true);setOutputStream(new OutputStream(){public void write(int b){} // not calledpublic void write(byte[] b, int off, int len){output.append(new String(b, off, len));}});}public void publish(LogRecord record){if (!frame.isVisible()) return;super.publish(record);flush();}
}