w7/ScoreCalculator.java

@@ -0,0 +1,38 @@
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+public class ScoreCalculator {
+    public static void main(String[] args) {
+        String filePath = "scores.txt";
+        int sum = 0;
+        int count = 0;
+
+        // try-with-resources 自动关闭流，无需手动 close()
+        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                try {
+                    // 处理数字格式错误
+                    int score = Integer.parseInt(line.trim());
+                    sum += score;
+                    count++;
+                } catch (NumberFormatException e) {
+                    System.err.println("警告：无法解析分数 '" + line + "'，跳过该数据。");
+                }
+            }
+
+            if (count > 0) {
+                double average = (double) sum / count;
+                System.out.printf("平均分：%.2f%n", average);
+            } else {
+                System.out.println("文件中没有有效分数数据。");
+            }
+
+        } catch (java.io.FileNotFoundException e) {
+            System.err.println("错误：文件不存在，请检查路径 '" + filePath + "'。");
+        } catch (IOException e) {
+            System.err.println("错误：读取文件失败 - " + e.getMessage());
+        }
+    }
+}

w8/Pair.java

@@ -0,0 +1,21 @@
+package w8;
+
+public class Pair<K,V> {
+    private K key;
+    private V value;
+    public Pair(K key,V value){
+        this.key=key;
+        this.value=value;
+    }
+    public K getKey(){
+        return key;
+    }
+    public V getValue(){
+        return value;
+    }
+    public static <K, V> Pair<V, K> swap(Pair<K, V> pair) {
+        return new Pair<>(pair.getValue(), pair.getKey());
+    }
+    
+}
+

w8/Test.java

@@ -0,0 +1,13 @@
+package w7;
+
+public class Test {
+    public static void main(String[] args) {
+        // 原始 Pair
+        Pair<String, Integer> original = new Pair<>("年龄", 18);
+        System.out.println("交换前：" + original);
+
+        // 调用静态 swap 方法交换键值
+        Pair<Integer, String> swapped = Pair.swap(original);
+        System.out.println("交换后：" + swapped);
+    }
+}