Java Read Each Line Into Separate Array
Question
I have 1,000 lines of data in a text file and I would like each line to be its own float [].
1,1,1,1,1,1
2,2,2,2,2,2
3,3,3,3,3,3
Would result in:
float[0] = {1,1,1,1,1,1}
float[1] = {2,2,2,2,2,2}
float[2] = {3,3,3,3,3,3}
Is this possible? I could only find examples of loading an entire file into an array. I tried hardcoding all the arrays, but exceeded the byte character limit of ~65,000
4 answers
solution1
3 2012-09-21 02:55:44
Try the following:
// this list will store all the created arrays
List<float[]> arrays = new ArrayList<float[]>();
// use a BufferedReader to get the handy readLine() function
BufferedReader reader = new BufferedReader(new FileReader("myfile.txt"));
// this reads in all the lines. If you only want the first thousand, just
// replace these loop conditions with a regular counter variable
for (String line = reader.readLine(); line != null; line = reader.readLine()) {
String[] floatStrings = line.split(",");
float[] floats = new float[floatStrings.length];
for (int i = 0; i < floats.length; ++i) {
floats[i] = Float.parseFloat(floatStrings[i]);
}
arrays.add(floats);
}
Note that I haven't added any exception handling (readLine(), for example, throws IOException).
solution2
0 2012-09-21 02:43:19
use a LineIterator to read each line without loading the whole file
for each line, use a regular expression to extract figures like (\\d\\.)+ and iterator over the matches found with methods like find() and group()
solution3
0 2021-11-22 08:23:44
<body> <pre> package FirstPrac; import java.io.FileReader; public class Check { public static void main(String[] args) { readingfile(); } public static void readingfile() { try { FileReader read = new FileReader("D:\\\\JavaWkspace\\\\numbers.txt"); int index; String nums1 = ""; while ((index = read.read()) != -1) { if (((char) index) != '\\n') { nums1 += String.valueOf((char) index); } } System.out.println("Problem statement: Print out the greatest number on each line:\\n" + nums1); String f = nums1.substring(0, 14); String s = nums1.substring(15, 29); String t = nums1.substring(30); String[] fs = f.split(","); int size = fs.length; int[] arr = new int[size]; for (int i = 0; i < size; i++) { arr[i] = Integer.parseInt(fs[i]); } int max = arr[0]; for (int i = 0; i < arr.length; i++) { if (max < arr[i]) { max = arr[i]; } } System.out.println("\\nGreatest number in the first line is:" + (max)); String[] sstr = s.split(","); int size2 = sstr.length; int[] arr2 = new int[size2]; for (int i = 0; i < size2; i++) { arr2[i] = Integer.parseInt(sstr[i]); } int max2 = arr2[0]; for (int i = 0; i < arr2.length; i++) { if (max2 < arr2[i]) { max2 = arr2[i]; } } System.out.println("\\nGreatest number in the second line is:" + (max2)); String[] str3 = t.split(","); int size3 = str3.length; int[] arr3 = new int[size3]; for (int i = 0; i < size3; i++) { arr3[i] = Integer.parseInt(str3[i]); } int max3 = arr3[0]; for (int i = 0; i < arr3.length; i++) { if (max3 < arr3[i]) { max3 = arr3[i]; } } System.out.println("\\nGreatest number in the third line is:" + (max3)); read.close(); } catch (Exception e) { System.out.println(e); } } } </pre> </body>
solution4
-1 2012-09-21 02:36:18
Loop over the line-delimited contents of the file with .split("\\n") and then cast each result as float array. Here's how to convert the string into a float for you => http://www.devdaily.com/java/edu/qanda/pjqa00013.shtml
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