Java 使用BufferedWriter写入字符串
我试图使用Java 使用BufferedWriter写入字符串,java,bufferedwriter,stringwriter,Java,Bufferedwriter,Stringwriter,我试图使用BufferedWriter在写入文件和写入字符串之间切换,但我从未使用BufferedWriter写入文件以外的任何内容 以可编译代码为例: public static void main(String[] args) { try (BufferedWriter fileWriter = new BufferedWriter(new FileWriter(new File("file.txt"))); StringWriter sw = new Str
BufferedWriter
在写入文件和写入字符串之间切换,但我从未使用BufferedWriter
写入文件以外的任何内容
以可编译代码为例:
public static void main(String[] args) {
try (BufferedWriter fileWriter = new BufferedWriter(new FileWriter(new File("file.txt")));
StringWriter sw = new StringWriter();
BufferedWriter stringWriter = new BufferedWriter(sw)) {
LinkedList<Record> records = new LinkedList<>();
records.add(new Record("name1", "text1", 20.4));
records.add(new Record("name2", "text2", -78));
records.add(new Record("name3", "text3", 11.56));
records.add(new Record("name4", "text4", 56));
records.add(new Record("name3", "text3", -44));
for(Record record : records) {
BufferedWriter writer;
if(record.amount < 0) {
writer = stringWriter; // write to string if amount is less than zero
} else {
writer = fileWriter; // write to file if not
}
writer.append(record.name);
writer.append(",");
writer.append(record.text);
writer.append(",");
writer.append(String.valueOf(record.amount));
writer.newLine();
}
String less_than_zero_amounts = sw.toString();
System.out.println("Less than zero:" + less_than_zero_amounts);
} catch (IOException e) {
e.printStackTrace();
}
}
static class Record {
String name;
String text;
double amount;
public Record(String name, String text, double amount) {
this.name = name;
this.text = text;
this.amount = amount;
}
public String getText() {
return text;
}
public String getName() {
return name;
}
public double getAmount() {
return amount;
}
}
但是程序的输出不会打印StringWriter
诚然,使用StringWriter
并将其交给BufferedWriter
是一种直觉。我可以将BufferedWriter
切换为字符串的任何方式都可以解决这个问题。您需要调用“flush()”将缓冲区的内容刷新到输出:
虽然我应该添加它,而不是在BufferedWriter对象之间进行选择,但您可能只想在对象之间进行选择。。。StringWriter有自己的缓冲区,因此无需在其上添加一层额外的BufferedWriter。对于FileWriter
,try with resources调用BufferedWriter
上的close()
,它会传播到FileWriter
,并刷新您编写的所有内容
StringWriter
也会发生同样的情况,但是在您尝试使用其内容之后,它就会发生,此时的内容是空的。在调用StringWriter
上的toString()
之前,需要flush()
相应的BufferedWriter
,我尝试使用Writer
,但它没有newline()
方法。
name1,text1,20.4
name3,text3,11.56
name4,text4,56.0