本文目錄一覽：
java io代碼學習
package IO;
import java.io.*;
public class FileDirectoryDemo {
public static void main(String[] args) {
// 如果沒有指定參數，則缺省為當前目錄。
if (args.length == 0) {
args = new String[] { “.” };
}
try {
// 新建指定目錄的File對象。
File currentPath = new File(args[0]);
// 在指定目錄新建temp目錄的File對象。
File tempPath = new File(currentPath, “temp”);
// 用“tempPath”對象在指定目錄下創建temp目錄。
tempPath.mkdir();
// 在temp目錄下創建兩個文件。
File temp1 = new File(tempPath, “temp1.txt”);
temp1.createNewFile();
File temp2 = new File(tempPath, “temp2.txt”);
temp2.createNewFile();
// 遞歸顯示指定目錄的內容。
System.out.println(“顯示指定目錄的內容”);
listSubDir(currentPath);
// 更改文件名“temp1.txt”為“temp.txt”。
File temp1new = new File(tempPath, “temp.txt”);
temp1.renameTo(temp1new);
// 遞歸顯示temp子目錄的內容。
System.out.println(“更改文件名後，顯示temp子目錄的內容”);
listSubDir(tempPath);
// 刪除文件“temp2.txt”。
temp2.delete();
// 遞歸顯示temp子目錄的內容。
System.out.println(“刪除文件後，顯示temp子目錄的內容”);
listSubDir(tempPath);
} catch (IOException e) {
System.err.println(“IOException”);
}
}
// 遞歸顯示指定目錄的內容。
static void listSubDir(File currentPath) {
// 取得指定目錄的內容列表。
String[] fileNames = currentPath.list();
try {
for (int i = 0; i fileNames.length; i++) {
File f = new File(currentPath.getPath(), fileNames[i]);
// 如果是目錄，則顯示目錄名後，遞歸調用，顯示子目錄的內容。
if (f.isDirectory()) {
// 以規範的路徑格式顯示目錄。
System.out.println(f.getCanonicalPath());
// 遞歸調用，顯示子目錄。
listSubDir(f);
}
// 如果是文件，則顯示文件名，不包含路徑信息。
else {
System.out.println(f.getName());
}
}
} catch (IOException e) {
System.err.println(“IOException”);
}
}
}
package IO;
import java.io.*;
public class FileExample {
public FileExample() {
super();// 調用父類的構造函數
}
public static void main(String[] args) {
try {
String outfile = “demoout.xml”;
// 定義了一個變量, 用於標識輸出文件
String infile = “demoin.xml”;
// 定義了一個變量, 用於標識輸入文件
DataOutputStream dt = new DataOutputStream(
new BufferedOutputStream(new FileOutputStream(outfile)));
/**
* 用FileOutputStream定義一個輸入流文件，
* 然後用BuferedOutputStream調用FileOutputStream對象生成一個緩衝輸出流
* 然後用DataOutputStream調用BuferedOutputStream對象生成數據格式化輸出流
*/
BufferedWriter NewFile = new BufferedWriter(new OutputStreamWriter(
dt, “gbk”));// 對中文的處理
DataInputStream rafFile1 = new DataInputStream(
new BufferedInputStream(new FileInputStream(infile)));
/**
*用FileInputStream定義一個輸入流文件，
* 然後用BuferedInputStream調用FileInputStream對象生成一個緩衝輸出流
* ，其後用DataInputStream中調用BuferedInputStream對象生成數據格式化輸出流
*/
BufferedReader rafFile = new BufferedReader(new InputStreamReader(
rafFile1, “gbk”));// 對中文的處理
String xmlcontent = “”;
char tag = 0;// 文件用字符零結束
while (tag != (char) (-1)) {
xmlcontent = xmlcontent + tag + rafFile.readLine() + ‘\n’;
}
NewFile.write(xmlcontent);
NewFile.flush();// 清空緩衝區
NewFile.close();
rafFile.close();
System.gc();// 強制立即回收垃圾，即釋放內存。
} catch (NullPointerException exc) {
exc.printStackTrace();
} catch (java.lang.IndexOutOfBoundsException outb) {
System.out.println(outb.getMessage());
outb.printStackTrace();
} catch (FileNotFoundException fex) {
System.out.println(“fex” + fex.getMessage());
} catch (IOException iex) {
System.out.println(“iex” + iex.getMessage());
}
}
}
package IO;
import java.io.*;
public class FileRandomRW {
// 需要輸入的person數目。
public static int NUMBER = 3;
public static void main(String[] args) {
Persons[] people = new Persons[NUMBER];
people[0] = new Persons(“張峰”, 26, 2000, “N”);
people[1] = new Persons(“艷娜”, 25, 50000, “Y”);
people[2] = new Persons(“李朋”, 50, 7000, “F”);
try {
DataOutputStream out = new DataOutputStream(new FileOutputStream(
“peoplerandom.dat”));
// 將人員數據保存至“peoplerandom.dat”二進制文件中。
writeData(people, out);
// 關閉流。
out.close();
// 從二進制文件“peoplerandom.dat”中逆序讀取數據。
RandomAccessFile inOut = new RandomAccessFile(“peoplerandom.dat”,
“rw”);
Persons[] inPeople = readDataReverse(inOut);
// 輸出讀入的數據。
System.out.println(“原始數據：”);
for (int i = 0; i inPeople.length; i++) {
System.out.println(inPeople[i]);
}
// 修改文件的第三條記錄。
inPeople[2].setSalary(4500);
// 將修改結果寫入文件。
inPeople[2].writeData(inOut, 3);
// 關閉流。
inOut.close();
// 從文件中讀入的第三條記錄，並輸出，以驗證修改結果。
RandomAccessFile in = new RandomAccessFile(“peoplerandom.dat”, “r”);
Persons in3People = new Persons();
// 隨機讀第三條記錄。
in3People.readData(in, 3);
// 關閉流。
in.close();
System.out.println(“修改後的記錄”);
System.out.println(in3People);
} catch (IOException exception) {
System.err.println(“IOException”);
}
}
// 將數據寫入輸出流。
static void writeData(Persons[] p, DataOutputStream out) throws IOException {
for (int i = 0; i p.length; i++) {
p[i].writeData(out);
}
}
// 將數據從輸入流中逆序讀出。
static Persons[] readDataReverse(RandomAccessFile in) throws IOException {
// 獲得記錄數目。
int record_num = (int) (in.length() / Persons.RECORD_LENGTH);
Persons[] p = new Persons[record_num];
// 逆序讀取。
for (int i = record_num – 1; i = 0; i–) {
p[i] = new Persons();
// 文件定位。
in.seek(i * Persons.RECORD_LENGTH);
p[i].readData(in, i + 1);
}
return p;
}
}
class Persons {
private String name;
private int age; // 4個字節
private double salary; // 8個字節
private String married;
public static final int NAME_LENGTH = 20; // 姓名長度
public static final int MARRIED_LENGTH = 2; // 婚否長度
public static final int RECORD_LENGTH = NAME_LENGTH * 2 + 4 + 8
+ MARRIED_LENGTH * 2;
public Persons() {
}
public Persons(String n, int a, double s) {
name = n;
age = a;
salary = s;
married = “F”;
}
public Persons(String n, int a, double s, String m) {
name = n;
age = a;
salary = s;
married = m;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public double getSalary() {
return salary;
}
public String getMarried() {
return married;
}
public String setName(String n) {
name = n;
return name;
}
public int setAge(int a) {
age = a;
return age;
}
public double setSalary(double s) {
salary = s;
return salary;
}
public String setMarried(String m) {
married = m;
return married;
}
// 設置輸出格式。
public String toString() {
return getClass().getName() + “[name=” + name + “,age=” + age
+ “,salary=” + salary + “,married=” + married + “]”;
}
// 寫入一條固定長度的記錄，即一個人的數據到輸出流。
public void writeData(DataOutput out) throws IOException {
FixStringIO.writeFixString(name, NAME_LENGTH, out);
out.writeInt(age);
out.writeDouble(salary);
FixStringIO.writeFixString(married, MARRIED_LENGTH, out);
}
// 寫入一條固定長度的記錄到隨機讀取文件中。
private void writeData(RandomAccessFile out) throws IOException {
FixStringIO.writeFixString(name, NAME_LENGTH, out);
out.writeInt(age);
out.writeDouble(salary);
FixStringIO.writeFixString(married, MARRIED_LENGTH, out);
}
// 隨機寫入一條固定長度的記錄到輸出流的指定位置。
public void writeData(RandomAccessFile out, int n) throws IOException {
out.seek((n – 1) * RECORD_LENGTH);
writeData(out);
}
// 從輸入流隨機讀入一條記錄，即一個人的數據。
private void readData(RandomAccessFile in) throws IOException {
name = FixStringIO.readFixString(NAME_LENGTH, in);
age = in.readInt();
salary = in.readDouble();
married = FixStringIO.readFixString(MARRIED_LENGTH, in);
}
// 從輸入流隨機讀入指定位置的記錄。
public void readData(RandomAccessFile in, int n) throws IOException {
in.seek((n – 1) * RECORD_LENGTH);
readData(in);
}
}
// 對固定長度字符串從文件讀出、寫入文件
class FixStringIO {
// 讀取固定長度的Unicode字符串。
public static String readFixString(int size, DataInput in)
throws IOException {
StringBuffer b = new StringBuffer(size);
int i = 0;
boolean more = true;
while (more i size) {
char ch = in.readChar();
i++;
if (ch == 0) {
more = false;
} else {
b.append(ch);
}
}
// 跳過剩餘的字節。
in.skipBytes(2 * (size – i));
return b.toString();
}
// 寫入固定長度的Unicode字符串。
public static void writeFixString(String s, int size, DataOutput out)
throws IOException {
int i;
for (i = 0; i size; i++) {
char ch = 0;
if (i s.length()) {
ch = s.charAt(i);
}
out.writeChar(ch);
}
}
}
package IO;
import java.io.*;
import java.util.*;
public class FileRW {
// 需要輸入的person數目。
public static int NUMBER = 3;
public static void main(String[] args) {
Person[] people = new Person[NUMBER];
// 暫時容納輸入數據的臨時字符串數組。
String[] field = new String[4];
// 初始化field數組。
for (int i = 0; i 4; i++) {
field[i] = “”;
}
// IO操作必須捕獲IO異常。
try {
// 用於對field數組進行增加控制。
int fieldcount = 0;
// 先使用System.in構造InputStreamReader，再構造BufferedReader。
BufferedReader stdin = new BufferedReader(new InputStreamReader(
System.in));
for (int i = 0; i NUMBER; i++) {
fieldcount = 0;
System.out.println(“The number ” + (i + 1) + ” person”);
System.out
.println(“Enter name,age,salary,married(optional),please separate fields by ‘:'”);
// 讀取一行。
String personstr = stdin.readLine();
// 設置分隔符。
StringTokenizer st = new StringTokenizer(personstr, “:”);
// 判斷是否還有分隔符可用。
while (st.hasMoreTokens()) {
field[fieldcount] = st.nextToken();
fieldcount++;
}
// 如果輸入married，則field[3]不為空，調用具有四個參數的Person構造函數。
if (field[3] != “”) {
people[i] = new Person(field[0],
Integer.parseInt(field[1]), Double
.parseDouble(field[2]), field[3]);
// 置field[3]為空，以備下次輸入使用。
field[3] = “”;
}
// 如果未輸入married，則field[3]為空，調用具有三個參數的Person構造函數。
else {
people[i] = new Person(field[0],
Integer.parseInt(field[1]), Double
.parseDouble(field[2]));
}
}
// 將輸入的數據保存至“people.dat”文本文件中。
PrintWriter out = new PrintWriter(new BufferedWriter(
new FileWriter(“people.dat”)));
writeData(people, out);
// 關閉流。
out.close();
// 從文件“people.dat”讀取數據。
BufferedReader in = new BufferedReader(new FileReader(“people.dat”));
Person[] inPeople = readData(in);
// 關閉流。
in.close();
// 輸出從文件中讀入的數據。
for (int i = 0; i inPeople.length; i++) {
System.out.println(inPeople[i]);
}
} catch (IOException exception) {
System.err.println(“IOException”);
}
}
// 將所有數據寫入輸出流。
static void writeData(Person[] p, PrintWriter out) throws IOException {
// 寫入記錄條數，即人數。
out.println(p.length);
for (int i = 0; i p.length; i++) {
p[i].writeData(out);
}
}
// 將所有數據從輸入流中讀出。
static Person[] readData(BufferedReader in) throws IOException {
// 獲取記錄條數，即人數。
int n = Integer.parseInt(in.readLine());
Person[] p = new Person[n];
for (int i = 0; i n; i++) {
p[i] = new Person();
p[i].readData(in);
}
return p;
}
}
class Person {
private String name;
private int age;
private double salary;
private String married;
public Person() {
}
public Person(String n, int a, double s) {
name = n;
age = a;
salary = s;
married = “F”;
}
public Person(String n, int a, double s, String m) {
name = n;
age = a;
salary = s;
married = m;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public double getSalary() {
return salary;
}
public String getMarried() {
return married;
}
// 設置輸出格式。
public String toString() {
return getClass().getName() + “[name=” + name + “,age=” + age
+ “,salary=” + salary + “,married=” + married + “]”;
}
// 寫入一條記錄，即一個人的數據到輸出流。
public void writeData(PrintWriter out) throws IOException {
// 格式化輸出。
out.println(name + “:” + age + “:” + salary + “:” + married);
}
// 從輸入流讀入一條記錄，即一個人的數據。
public void readData(BufferedReader in) throws IOException {
String s = in.readLine();
StringTokenizer t = new StringTokenizer(s, “:”);
name = t.nextToken();
age = Integer.parseInt(t.nextToken());
salary = Double.parseDouble(t.nextToken());
married = t.nextToken();
}
}
package IO;
import java.io.IOException;
public class FileStdRead {
public static void main(String[] args) throws IOException {
int b = 0;
char c = ‘ ‘;
System.out.println(“請輸入：”);
while (c != ‘q’) {
int a = System.in.read();
c = (char) a;
b++;
System.out.println((char) a);
}
System.err.print(“counted\t” + b + “\ttotalbytes.”);
}
}
//讀取輸入的數據,直到數據中有Q這個字母然
package IO;
import java.io.*;
public class IOStreamExample {
public static void main(String[] args) throws IOException {
// 1. 讀入一行數據:
BufferedReader in = new BufferedReader(new FileReader(
“FileStdRead.java”));
String s, s2 = new String();
while ((s = in.readLine()) != null) {
s2 += s + “\n”;
}
in.close();
BufferedReader stdin = new BufferedReader(new InputStreamReader(
System.in));
System.out.print(“Enter a line:”);
System.out.println(stdin.readLine());
// 2. 從內存中讀入
StringReader in2 = new StringReader(s2);
int c;
while ((c = in2.read()) != -1) {
System.out.print((char) c);
}
// 3. 格式化內存輸入
try {
DataInputStream in3 = new DataInputStream(new ByteArrayInputStream(
s2.getBytes()));
while (true) {
System.out.print((char) in3.readByte());
}
} catch (EOFException e) {
System.err.println(“End of stream”);
}
// 4. 文件輸入
try {
BufferedReader in4 = new BufferedReader(new StringReader(s2));
PrintWriter out1 = new PrintWriter(new BufferedWriter(
new FileWriter(“IODemo.out”)));
int lineCount = 1;
while ((s = in4.readLine()) != null) {
out1.println(lineCount++ + “: ” + s);
}
out1.close();
} catch (EOFException e) {
System.err.println(“End of stream”);
}
// 5. 接收和保存數據
try {
DataOutputStream out2 = new DataOutputStream(
new BufferedOutputStream(new FileOutputStream(“Data.txt”)));
out2.writeDouble(3.14159);
out2.writeUTF(“That was pi”);
out2.writeDouble(1.41413);
out2.writeUTF(“Square root of 2”);
out2.close();
DataInputStream in5 = new DataInputStream(new BufferedInputStream(
new FileInputStream(“Data.txt”)));
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
} catch (EOFException e) {
throw new RuntimeException(e);
}
// 6. 隨機讀取文件內容
RandomAccessFile rf = new RandomAccessFile(“rtest.dat”, “rw”);
for (int i = 0; i 10; i++) {
rf.writeDouble(i * 1.414);
}
rf.close();
rf = new RandomAccessFile(“rtest.dat”, “rw”);
rf.seek(5 * 8);
rf.writeDouble(47.0001);
rf.close();
rf = new RandomAccessFile(“rtest.dat”, “r”);
for (int i = 0; i 10; i++) {
System.out.println(“Value ” + i + “: ” + rf.readDouble());
}
rf.close();
}
}
package IO;
import java.io.*;
/**
* p
* Title: JAVA進階訣竅
* /p
*
* @author 張峰
* @version 1.0
*/
public class MakeDirectoriesExample {
private static void fileattrib(File f) {
System.out.println(“絕對路徑: ” + f.getAbsolutePath() + “\n 可讀屬性: “
+ f.canRead() + “\n 可定屬性: ” + f.canWrite() + “\n 文件名: “
+ f.getName() + “\n 父目錄: ” + f.getParent() + “\n 當前路徑: “
+ f.getPath() + “\n 文件長度: ” + f.length() + “\n 最後更新日期: “
+ f.lastModified());
if (f.isFile()) {
System.out.println(“輸入的是一個文件”);
} else if (f.isDirectory()) {
System.out.println(“輸入的是一個目錄”);
}
}
public static void main(String[] args) {
if (args.length 1) {
args = new String[3];
}
args[0] = “d”;
args[1] = “test1.txt”;
args[2] = “test2.txt”;
File old = new File(args[1]), rname = new File(args[2]);
old.renameTo(rname);
fileattrib(old);
fileattrib(rname);
int count = 0;
boolean del = false;
if (args[0].equals(“d”)) {
count++;
del = true;
}
count–;
while (++count args.length) {
File f = new File(args[count]);
if (f.exists()) {
System.out.println(f + ” 文件己經存在”);
if (del) {
System.out.println(“刪除文件” + f);
f.delete();
}
} else { // 如果文件不存在
if (!del) {
f.mkdirs();
System.out.println(“創建文件： ” + f);
}
}
fileattrib(f);
}
}
}
求一段java代碼
public class Student {
String name;
String sex;
int age;
public Student(){}
public Student(String name,String sex,int age){
this.name=name;
this.sex=sex;
this.age=age;
}
/**
* PrintINFO
*/
public void printStudentInfo(){
System.err.println(“Name: “+name);
System.err.println(“Sex: “+sex);
System.err.println(“Age: “+age);
}
public static void main(String[] args) {
try {
Class? st = (Class?) Class.forName(“Student”);
Student student=(Student) st.newInstance();
student.name=”java”;
student.sex=”男”;
student.age=20;
Method[] methods=st.getMethods();
for (int i = 0; i methods.length; i++) {
if(methods[i].getName().equals(“printStudentInfo”)){
methods[i].invoke(student);
}
System.out.println(“類方法結構:”+methods[i].getName());
}
Field[] s= st.getDeclaredFields();
for (int i = 0; i s.length; i++) {
System.out.println(“類的結構字段:”+s[i].getName());
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
求用Java編寫的學生成績管理系統的完整代碼
package jdbcproj;
import java.sql.*;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.awt.event.ActionEvent;
public class MainFrame extends JFrame {
private JPanel contentPane;
private JTextField txtname;
private JTextField txtpassword;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainFrame frame = new MainFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public MainFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 661, 399);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lblNewLabel = new JLabel(“\u7528\u6237\u540D”);
lblNewLabel.setBounds(114, 51, 72, 18);
contentPane.add(lblNewLabel);
JLabel lblNewLabel_1 = new JLabel(“\u5BC6\u7801”);
lblNewLabel_1.setBounds(114, 106, 72, 18);
contentPane.add(lblNewLabel_1);
txtname = new JTextField();
txtname.setBounds(261, 48, 86, 24);
contentPane.add(txtname);
txtname.setColumns(10);
txtpassword = new JTextField();
txtpassword.setBounds(261, 103, 86, 24);
contentPane.add(txtpassword);
txtpassword.setColumns(10);
JButton btnadd = new JButton(“\u589E\u52A0”);
btnadd.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(txtname.getText().equals(“”)||txtpassword.getText().equals(“”))
{
JOptionPane.showMessageDialog(getContentPane(), “用戶名和密碼不能為空”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
else{
Users u=new Users();
u.setPwd(txtpassword.getText());
u.setUsername(txtname.getText());
UserDAO usdo=new UserDAO();
usdo.addUser(u);
}
}
});
btnadd.setBounds(45, 205, 113, 27);
contentPane.add(btnadd);
JButton btndelete = new JButton(“\u5220\u9664”);
btndelete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
if(txtname.getText().equals(“”))
{
JOptionPane.showMessageDialog(getContentPane(), “用戶名不能為空”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
else{
UserDAO usdo=new UserDAO();
usdo.delUser(txtname.getText());;
}
}
});
btndelete.setBounds(172, 205, 113, 27);
contentPane.add(btndelete);
JButton btnupdate = new JButton(“\u4FEE\u6539”);
btnupdate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(txtname.getText().equals(“”)||txtpassword.getText().equals(“”))
{
JOptionPane.showMessageDialog(getContentPane(), “用戶名和密碼不能為空”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
else{
Users u=new Users();
u.setPwd(txtpassword.getText());
u.setUsername(txtname.getText());
UserDAO usdo=new UserDAO();
usdo.updateUser(u);;
}
}
});
btnupdate.setBounds(300, 205, 113, 27);
contentPane.add(btnupdate);
JButton btnfind = new JButton(“\u67E5\u8BE2”);
btnfind.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(txtname.getText().equals(“”))
{
JOptionPane.showMessageDialog(getContentPane(), “用戶名不能為空”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
else{
Users u=new Users();
UserDAO usdo=new UserDAO();
u=usdo.findUser(txtname.getText(), txtpassword.getText());
if(u!=null){
JOptionPane.showMessageDialog(getContentPane(), “該用戶存在！”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
else{
JOptionPane.showMessageDialog(getContentPane(), “該用戶不存在！”,”提示信息框”,JOptionPane.WARNING_MESSAGE);
}
}
}
});
btnfind.setBounds(427, 205, 113, 27);
contentPane.add(btnfind);
//記得要寫這個
setVisible(true);
}
}
Java編程，填寫下面的代碼
class NoLowerLetterException extends Exception {
public NoLowerLetterException(String msg) {
super(msg);
}
}
class NoDigitException extends Exception {
public NoDigitException(String msg) {
super(msg);
}
}
class People {
void printLetter(char c) {
if (c = ‘a’ c = ‘z’) {
System.out.println(c);
} else {
try {
throw new NoLowerLetterException(String.valueOf(c));
} catch (NoLowerLetterException e) {
e.printStackTrace();
}
}
}
void printDigit(char c) {
if (c = ‘0’ c = ‘9’) {
System.out.println(c);
} else {
try {
throw new NoDigitException(String.valueOf(c));
} catch (NoDigitException e) {
e.printStackTrace();
}
}
}
}
public class ExceptionExample {
public static void main(String args[]) {
People people = new People();
for (int i = 0; i 128; i++) {
// 【代碼5】
// //將i轉換為char類型，執行people.printLetter()方法，如果出現異常則捕獲，並輸出異常的錯誤信息！
people.printLetter((char) i);
}
for (int i = 0; i 128; i++) {
// 【代碼6】 //將i轉換為char類型，執行people. printDigit
// ()方法，如果出現異常則捕獲，並輸出異常的錯誤信息！
people.printDigit((char) i);
}
}
}
原創文章，作者：ECFW，如若轉載，請註明出處：https://www.506064.com/zh-hant/n/133518.html
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