java split用法 案例

需求：java读取一个csv文件并将文件内容每行按照","隔开

场景一：

读取1.csv文件：文件内容如下：

1,zhangsan,note
2,lisi,

注意：第二行逗号后面没有数据

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public static void main(String[] args) {         String csvFile = "C:\\Users\\yc\\Desktop\\1.csv";         String line;         try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {             // 读取CSV文件的每一行             while ((line = br.readLine()) != null) {                 // 根据分隔符拆分行数据                 String[] data = line.split(",");                 // 打印行数据                 System.out.println("-----------长度："+data.length);                 for(int i=0;i<data.length;i++){                     System.out.println(data[i]);                 }             }         } catch (IOException e) {             e.printStackTrace();         }     }

输出结果：两行分割后数据长度不一样

 如何让分割后的长度一样，避免下标溢出报错？修改代码，重点如下红色部分line.split(",",-1);加个-1

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public static void main(String[] args) {         String csvFile = "C:\\Users\\yc\\Desktop\\1.csv";         String line;         try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {             // 读取CSV文件的每一行             while ((line = br.readLine()) != null) {                 // 根据分隔符拆分行数据                 String[] data = line.split(",",-1);                 // 打印行数据                 System.out.println("-----------长度："+data.length);                 for(int i=0;i<data.length;i++){                     System.out.println(data[i]);                 }             }         } catch (IOException e) {             e.printStackTrace();         }     }

 输出结果：长度一样了，第二行输出了一个空，如下图所示。

 

场景二：

读取2.csv文件：文件内容如下：

aaa,"[123213,123123]",bbbb

想分割成aaa,"[123213,123123]"和bbbb

上代码如下：

 

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public static void main(String[] args) {        String csvFile = "C:\\Users\\yc\\Desktop\\2.csv";        String line;        try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {            // 读取CSV文件的每一行            while ((line = br.readLine()) != null) {                // 根据分隔符拆分行数据                String[] data = line.split(",",-1);                // 打印行数据                System.out.println("-----------长度："+data.length);                for(int i=0;i<data.length;i++){                    System.out.println(data[i]);                }            }        } catch (IOException e) {            e.printStackTrace();        }    }

 

 输出结果：事与愿违并没有出处想要的结果

 修改代码：

 

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public static void main(String[] args) {         String csvFile = "C:\\Users\\yc\\Desktop\\2.csv";         String line;         try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {             // 读取CSV文件的每一行             while ((line = br.readLine()) != null) {                 // 根据分隔符拆分行数据                 List<String> data = splitString(line);                 // 打印行数据                 System.out.println("-----------长度："+data.size());                 for(int i=0;i<data.size();i++){                     System.out.println(data.get(i));                 }             }         } catch (IOException e) {             e.printStackTrace();         }     }       public static List<String> splitString(String text) {         List<String> result = new ArrayList<>();         boolean inQuotes = false;         StringBuilder sb = new StringBuilder();           for (char c : text.toCharArray()) {             if (c == '\"') {                 inQuotes = !inQuotes;                 sb.append(c);             } else if (c == ',' && !inQuotes) {                 result.add(sb.toString());                 sb.setLength(0);             } else {                 sb.append(c);             }         }         result.add(sb.toString());           return result;     }

输出结果：得到了想要的结果