CSV数据到2d数组java
我可能走错了方向,但我的问题是,我该如何填充fxRates的数组CSV数据到2d数组java,java,file,Java,File,我可能走错了方向,但我的问题是,我该如何填充fxRates的数组 CAD,EUR,GBP,USD 1.0,0.624514066,0.588714763,0.810307 1.601244959,1.0,0.942676548,1.2975 1.698615463,1.060809248,1.0,1.3764 1.234100162,0.772200772,.726532984,1.0 这是CSV文件中的信息,我正在考虑使用scanner类来读取它。差不多 private double[][]
CAD,EUR,GBP,USD
1.0,0.624514066,0.588714763,0.810307
1.601244959,1.0,0.942676548,1.2975
1.698615463,1.060809248,1.0,1.3764
1.234100162,0.772200772,.726532984,1.0
这是CSV文件中的信息,我正在考虑使用scanner类来读取它。差不多
private double[][] fxRates;
String delimiter = ","
Scanner sc = new Scanner(file);
while (sc.hasNextLine()) {
String line = sc.nextLine();
fxRates = line.split(delimiter)
你解决这个问题的方法似乎还可以。但是
line.split(“,”)
将返回一个1D字符串数组。您不能将其分配给fxRates
。而且您还应该知道行数,以便在开始时初始化fxRates
。否则,您应该使用动态列表结构,如ArrayList
假设您的文件中有50行,您可以使用以下内容:
private String[][] fxRates = String[50][];
String delimiter = ",";
Scanner sc = new Scanner(file);
int index=0;
while (sc.hasNextLine())
{
String line = sc.nextLine();
fxRates[index++] = line.split(delimiter)
}
请注意,我已将
fxRates
声明为2D字符串数组,如果需要双值,则应就地或稍后进行一些转换。拆分操作的结果是字符串
数组,而不是双值
数组。因此缺少一个步骤:将字符串转换为双精度:
private double[][] fxRates = new double[maxLines][4];
String delimiter = ","
int line = 0;
Scanner sc = new Scanner(file);
while (sc.hasNextLine()) {
String line = sc.nextLine();
String[] fxRatesAsString = line.split(delimiter);
for (int i = 0; i < fxRatesAsString.length; i++) {
fxRates[line][i] = Double.parseDouble(fxRatesAsString[i]);
}
private double[]fxRates=new double[maxLines][4];
字符串分隔符=“,”
内线=0;
扫描仪sc=新扫描仪(文件);
while(sc.hasNextLine()){
字符串行=sc.nextLine();
String[]fxRatesAsString=line.split(分隔符);
对于(int i=0;i
另一个例子
Double[][] fxRates = new Double[4][];
String delimiter = ",";
//file code goes here
Scanner sc = new Scanner(file);
// Read File Line By Line
int auxI = 0;
// Read File Line By Line
for (int auxI =0; sc.hasNextLine(); auxI++) {
String line = sc.nextLine();
System.out.println(line);
String[] fxRatesAsString = line.split(delimiter);
Double[] fxRatesAsDouble = new Double[fxRatesAsString.length];
for (int i = 0; i < fxRatesAsString.length; i++) {
fxRatesAsDouble[i] = Double.parseDouble(fxRatesAsString[i]);
}
fxRates[auxI] = fxRatesAsDouble;
}
//to double check it
for (int y =0; y<fxRates.length; y++){
for (int x =0; x<fxRates.length; x++){
System.out.print(fxRates[y][x] +" ");
}
System.out.println("");
}
Double[]fxRates=new Double[4][];
字符串分隔符=“,”;
//文件代码在这里
扫描仪sc=新扫描仪(文件);
//逐行读取文件
int auxI=0;
//逐行读取文件
for(int auxI=0;sc.hasNextLine();auxI++){
字符串行=sc.nextLine();
系统输出打印项次(行);
String[]fxRatesAsString=line.split(分隔符);
Double[]fxratesasdoull=新的双精度[fxratesastring.length];
对于(int i=0;i 对于(It y=0;y我不建议您以这样的方式解析CSV,因为<代码>扫描器太低级别和原始的解决方案。相比之下,DOM/SAX解析器更好地解析XML而不是正则表达式解析或不考虑文档结构的任何东西。有CSV解析器,具有良好的API和SUGG。读卡器初始化期间的est配置选项。只需看一下易于使用。以下是使用它的代码示例:
q12967756包;
导入java.io.IOException;
导入java.io.StringReader;
导入java.util.ArrayList;
导入java.util.Collection;
导入静态java.lang.Double.parseDouble;
导入静态java.lang.System.out;
进口com.csvreader.csvreader;
公开期末班{
专用干管(){
}
私有静态最终字符串模拟=
CAD、欧元、英镑、美元\n+
“1.0,0.624514066,0.588714763,0.810307\n”+
“1.601244959,1.0,0.942676548,1.2975\n”+
“1.698615463,1.060809248,1.0,1.3764\n”+
“1.23410162,0.772200772,726532984,1.0\n”;
私有静态最终字符分隔符=',';
公共静态void main(字符串[]args)引发IOException{
//final FileReader contentReader=newfilereader(“yourfile.csv”);
最终StringReader contentReader=新StringReader(模拟);
最终CsvReader csv=新CsvReader(内容阅读器、分隔符);
csv.readHeaders();//跳过'CAD、EUR、GBP、USD`
最终收集温度=新的ArrayList();
而(csv.readRecord()){
临时添加(parseRawValues(csv.getValues());
}
最终双精度[]阵列2d=临时阵列(新双精度[temp.size()][]);
out.println(array2d[3][1]);
}
私有静态双[]parseRawValues(字符串[]rawValues){
最终整数长度=rawValues.length;
最终双精度[]值=新双精度[长度];
for(int i=0;i
如果手动解析CSV,那就是自找麻烦。
import java.nio.charset.Charset;
import java.nio.file.Paths;
import java.nio.file.Files;
import java.io.IOException;
public class CSVReader{
private String readFile(String path, Charset encoding) throws IOException
{
//Read in all bytes from a file at the specified path into a byte array
//This method will fail if there is no file to read at the specified path
byte[] encoded = Files.readAllBytes(Paths.get(path));
//Convert the array of bytes into a string.
return new String(encoded, encoding);
}
public String readFile(String path)
{
try {
//Read the contents of the file at the specified path into one long String
String content = readFile(path, Charset.defaultCharset());
//Display the string. Feel free to comment this line out.
System.out.println("File contents:\n"+content+"\n\n");
//Return the string to caller
return content;
}catch (IOException e){
//This code will only execute if we could not open a file
//Display the error message
System.out.println("Cannot read file "+path);
System.out.println("Make sure the file exists and the path is correct");
//Exit the program
System.exit(1);
}`enter code here`
return null;
}
}