Java用字母和数字解析Sting的整数

Question

I'm working with data that is a String followed by spaces and then a numeric value.

ncols         10812
nrows         10812
xllcorner     -107.0005555556
yllcorner     36.99944444444
cellsize      9.2592592593e-05

I'm trying to just read in just the numeric value. I know that from going to String to Integer or Double I can use the standard type conversions.

Integer.valueOf(stringOfInteger);
Double.valueOf(stringOfDouble);

In order to get just the numeric value I tried this as a test:

BufferedReader br = new BufferedReader(new FileReader(path));
String line = br.readLine();
line.replace("[a-z]","");
line.replace(" ","");
System.out.println(line);

and it output ncols 10812

I'm also worried about reading the cellsize value as it has an exponential.

Answer 1

You can do this for each line:

...
String[] fields = line.split("\\s+");
String name = fields[0];
float value = Float.parseFloat(fields[1]);
...

This code will split each line in fields using the spaces as a separator. The first field is a String so you can use it directly (or ignore it). The second one is a Float value so you have to convert it before using it. You can use Double if you prefer.

Answer 2

Try this one

    BufferedReader br = new BufferedReader(new FileReader(path));
    String line = null;
    while ((line = br.readLine()) != null) {
        // split each line based on spaces
        String[] words = line.split("\\s+");
        //first word is name
        String name = words[0];
        // next word is actual number
        Double value = Double.valueOf(words[1]);
        System.out.println(name + ":" + value);
    }
    // don't forget to close the stream
    br.close();

Output:

    ncols:10812.0
    nrows:10812.0
    xllcorner:-107.0005555556
    yllcorner:36.99944444444
    cellsize:9.2592592593E-5

Answer 3

If all you want all the numeric values do a split on the space and the second item will contain your numeric value. Then you can do any conversions as needed and not have to worry about removing any exponents.

String[] data = new line.split(" ");
//remove all the spaces from the second array for your data
data[1] = data[1].replaceAll("\\s", "");
//parse to whatever you need data[1] to be

Answer 4

You could use the split function in Java as follows:

String [] dataArr = data.split("[ \t]+"); //assumes @data is you data string variable name

The dataArr , then, will look like this:

dataArr[0] =  "ncols"
dataArr[1] =  "10812"
dataArr[2] =  "nrows"
dataArr[3] =  "10812"
.
.
.

dataArr[n - 1] = "9.2592592593e-05"   // @n is the size of the array

You could, then, use the Integer.parseInt(String str) to parse your numerical data into integers.