這是代碼：import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;import java.io.FileReader;import java.io.BufferedReader;import java.util.stream.Collectors;import java.io.FileWriter;import java.io.BufferedWriter;import java.util.List;public class CSVIO{ //read a file and return a list of records in the file public static List<String[]> read(File f) throws IOException { BufferedReader br = new BufferedReader(new FileReader(f)); List<String[]> out = br.lines() .map( e -> e.split(",")) .collect(Collectors.toList()); return out; } //write from a list of recrords into CSV format public static void write(List<String[]> items, File dest) throws IOException { //return true if it successfully writes. final BufferedWriter bw = new BufferedWriter(new FileWriter(dest)); items.stream() .map( row -> String.join(",", row)) .forEach( row -> bw.write(row + "\n")); }}我在運行時收到此錯誤消息：$ javac CSVIO.javaCSVIO.java:29: error: unreported exception IOException; must be caught or declared to be thrown .forEach( row -> bw.write(row + "\n")); ^1 error我已正確聲明 write 方法會引發異常。有什么我想念的嗎？
1 回答
Smart貓小萌
TA貢獻1911條經驗 獲得超7個贊
問題是，你br.write()拋出了異常。您必須在 lambda 表達式 ( .forEach()) 中捕捉到這一點：
items.stream()
.map(row -> String.join(",", row))
.forEach( row -> {
try {
bw.write(row + "\n");
} catch (IOException e) {
e.printStackTrace();
}
});
但是您可以使用以下方法縮短它Files.write()：
public static void write(List<String[]> items, Path path) throws IOException {
List<String> lines = items.stream()
.map(row -> String.join(",", row))
.collect(Collectors.toList());
Files.write(path, lines);
}
您還可以使用以下方法簡化您的read方法Files.lines()：
public static List<String[]> read(Path path) throws IOException {
try (Stream<String> lines = Files.lines(path)) {
return lines
.map(e -> e.split(","))
.collect(Collectors.toList());
}
}
添加回答
舉報
0/150
提交
取消