Java Tutorial/File/LineNumberReader
Версия от 20:44, 31 мая 2010; (обсуждение)
Compare text file line by line
<source lang="java">
/*
- Copyright 2004 The Apache Software Foundation
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
- http://www.apache.org/licenses/LICENSE-2.0
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- /
//based on Apache technology http://www.apache.org import java.io.IOException; import java.io.LineNumberReader; import java.io.Reader; import java.util.List;
public class Diff {
public static void readersAsText(Reader r1, String name1, Reader r2, String name2, List diffs) throws IOException { LineNumberReader reader1 = new LineNumberReader(r1); LineNumberReader reader2 = new LineNumberReader(r2); String line1 = reader1.readLine(); String line2 = reader2.readLine(); while (line1 != null && line2 != null) { if (!line1.equals(line2)) { diffs.add("File \"" + name1 + "\" and file \"" + name2 + "\" differ at line " + reader1.getLineNumber() + ":" + "\n" + line1 + "\n" + line2); break; } line1 = reader1.readLine(); line2 = reader2.readLine(); } if (line1 == null && line2 != null) diffs.add("File \"" + name2 + "\" has extra lines at line " + reader2.getLineNumber() + ":\n" + line2); if (line1 != null && line2 == null) diffs.add("File \"" + name1 + "\" has extra lines at line " + reader1.getLineNumber() + ":\n" + line1); }
}</source>
Use LineNumberReader class to read file
<source lang="java">
import java.io.File; import java.io.FileReader; import java.io.LineNumberReader; public class Main {
public static void main(String[] args) throws Exception { File file = new File("data.csv"); FileReader fr = new FileReader(file); LineNumberReader lnr = new LineNumberReader(fr); // lnr.setLineNumber(400); String line = ""; while ((line = lnr.readLine()) != null) { System.out.println("Line Number " + lnr.getLineNumber() + ": " + line); } fr.close(); lnr.close(); }
}</source>
Using the LineNumberReader to read a text file line by line
<source lang="java">
import java.io.FileReader; import java.io.LineNumberReader; public class Main {
public static void main(String[] args) throws Exception { LineNumberReader r = new LineNumberReader(new FileReader("yourFile.txt")); String line = null; while ((line = r.readLine()) != null) { System.out.println(r.getLineNumber() + ": " + line); } r.close(); }
}</source>