读写文件文件

src/chapter7/Example08.java

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+package chapter7;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+public class Example08 {
+    public static void main(String[] args) {
+        // 使用try-with-resources自动关闭资源
+        try (FileWriter writer = new FileWriter("note.txt")) {
+            // 写入一些文本
+            writer.write("这是第一行\n");  // \n表示换行
+            writer.write("这是第二行\n");
+            System.out.println("文件写入成功！");
+
+        } catch (IOException e) {
+            System.out.println("写入文件出错：" + e.getMessage());
+        }
+    }
+}

src/chapter7/Example09.java

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+package chapter7;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+public class Example09 {
+    public static void main(String[] args) {
+        FileWriter writer = null;  // 在try外声明，以便finally中可以访问
+        try {
+            writer = new FileWriter("note.txt");
+            writer.write("这是第一行\n");
+            writer.write("这是第二行\n");
+            System.out.println("文件写入成功！");
+        } catch (IOException e) {
+            System.out.println("写入文件出错：" + e.getMessage());
+        } finally {
+            // 在finally中确保关闭资源
+            if (writer != null) {  // 防止writer未初始化就抛出异常
+                try {
+                    writer.close();  // close()方法也可能抛出IOException
+                } catch (IOException e) {
+                    System.out.println("关闭文件出错：" + e.getMessage());
+                }
+            }
+        }
+
+    }
+}

src/chapter7/Example10.java

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+package chapter7;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+public class Example10 {
+    public static void main(String[] args) {
+        // 使用try-with-resources自动关闭资源
+        try (BufferedReader reader = new BufferedReader(
+                new FileReader("note.txt"))) {
+
+            String line;
+            // 逐行读取文件内容
+            while ((line = reader.readLine()) != null) {
+                System.out.println(line);
+            }
+
+        } catch (IOException e) {
+            System.out.println("读取文件出错：" + e.getMessage());
+        }
+    }
+}

src/chapter7/FileOperationHomework.java

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+package chapter7;
+
+import java.io.*;
+import java.util.Scanner;
+
+public class FileOperationHomework {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        // 1. 获取文件名
+        System.out.print("请输入文件名：");
+        String fileName = scanner.nextLine();
+
+        // 2. 获取要写入的行数
+        System.out.print("请输入要写入的行数：");
+        int lines = scanner.nextInt();
+        scanner.nextLine(); // 消除换行符
+
+        // 3. 写入文件
+        try (FileWriter writer = new FileWriter(fileName)) {
+            // 循环获取用户输入并写入
+            for (int i = 1; i <= lines; i++) {
+                System.out.print("请输入第" + i + "行内容：");
+                String content = scanner.nextLine();
+                writer.write(content + "\n");
+            }
+            System.out.println("文件写入成功！");
+
+        } catch (IOException e) {
+            System.out.println("写入文件出错：" + e.getMessage());
+            return;  // 如果写入出错，直接返回
+        }
+
+        // 4. 读取并显示文件内容
+        System.out.println("\n文件内容如下：");
+        System.out.println("--------------------");
+
+        try (BufferedReader reader = new BufferedReader(
+                new FileReader(fileName))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                System.out.println(line);
+            }
+            System.out.println("--------------------");
+
+        } catch (IOException e) {
+            System.out.println("读取文件出错：" + e.getMessage());
+        }
+    }
+}