Java – how to use the Detect the first and last lines in readline()?
•
Java
I read each line of the file in the following way
BufferedReader in = new BufferedReader(new FileReader(inFile));
while (null != (line = in.readLine())) {
}
I want to do some validation separately on the first and last lines Did you check whether it is the first and last line in the while loop
while (null != (line = in.readLine())) {
if(firstlineoffile) {
}
else if (lastlineoffile) {
}
else
{
}
}
Solution
Cool question I played a circle, this is an sscce, just copy 'n' paste 'n' run it
package com.stackoverflow.q2292917;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
public class Test {
public static void main(String... args) throws IOException {
// Create test file.
File file = new File("/test.txt");
PrintWriter writer = new PrintWriter(file);
writer.println("line 1");
writer.println("line 2");
writer.println("line 3");
writer.println("line 4");
writer.println("line 5");
writer.close();
// Read test file.
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(file));
String next,line = reader.readLine();
for (boolean first = true,last = (line == null); !last; first = false,line = next) {
last = ((next = reader.readLine()) == null);
if (first) {
System.out.println("first line: " + line);
} else if (last) {
System.out.println("last line: " + line);
} else {
System.out.println("normal line: " + line);
}
}
} finally {
if (reader != null) try { reader.close(); } catch (IOException logorIgnore) {}
}
// Delete test file.
file.delete();
}
}
Output:
first line: line 1 normal line: line 2 normal line: line 3 normal line: line 4 last line: line 5
However, I question the readability and interpretability of beginners...;)
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