Java/File Input Output/BufferedWriter
Содержание
- 1 Appending to a File
- 2 Create BufferedWriter from FileWriter and write strings to the file
- 3 Nested creation of FileWriter, BufferedWriter and PrintWriter
- 4 new BufferedWriter(new OutputStreamWriter(System.out))
- 5 Read Input From User and Write to File
- 6 Use a BufferedReader and a BufferedWriter to copy a text file, inverting the case of letters in the process
- 7 Write text file
- 8 Write to file using a BufferedWriter
- 9 Writing to a File: If the file does not exist, it is automatically created.
Appending to a File
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; public class Main {
public static void main(String[] argv) throws Exception { BufferedWriter out = new BufferedWriter(new FileWriter("filename", true)); out.write("aString"); out.close(); }
}
</source>
Create BufferedWriter from FileWriter and write strings to the file
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; class BufferedWriterDemo {
public static void main(String args[]) throws Exception { FileWriter fw = new FileWriter(args[0]); BufferedWriter bw = new BufferedWriter(fw); // Write strings to the file for (int i = 0; i < 12; i++) { bw.write("Line " + i + "\n"); } // Close buffered writer bw.close(); }
}
</source>
Nested creation of FileWriter, BufferedWriter and PrintWriter
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; import java.io.PrintWriter; public class Main {
public static void main(String[] argv) throws Exception { FileWriter file = new FileWriter("a.html"); BufferedWriter buffer = new BufferedWriter(file); PrintWriter out = new PrintWriter(buffer); out.println("<html>\n\t<body>"); out.println("\t</body>\n</html>"); out.close(); buffer.close(); file.close(); }
}
</source>
new BufferedWriter(new OutputStreamWriter(System.out))
<source lang="java">
import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.InputStreamReader; import java.io.OutputStreamWriter; public class Main {
public static void main(String[] args) throws Exception { BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String strLine = in.readLine(); BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out)); out.write(strLine, 0, strLine.length()); out.flush(); in.close(); out.close(); }
}
</source>
Read Input From User and Write to File
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; import java.io.InputStream; public class Main {
public static void main(String[] args) throws Exception { InputStream in = System.in; BufferedWriter bw = new BufferedWriter(new FileWriter("output.txt")); int letter; while ((letter = in.read()) != -1) { bw.write((char) letter); bw.flush(); } }
}
</source>
Use a BufferedReader and a BufferedWriter to copy a text file, inverting the case of letters in the process
<source lang="java">
import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; public class Main {
public static void main(String[] argv) throws Exception { BufferedReader br = new BufferedReader(new FileReader("in.txt")); BufferedWriter bw = new BufferedWriter(new FileWriter("out.txt")); int i; do { i = br.read(); if (i != -1) { if (Character.isLowerCase((char) i)) bw.write(Character.toUpperCase((char) i)); else if (Character.isUpperCase((char) i)) bw.write(Character.toLowerCase((char) i)); else bw.write((char) i); } } while (i != -1); br.close(); bw.close(); }
}
</source>
Write text file
<source lang="java">
import java.io.BufferedWriter; import java.io.File; import java.io.FileWriter; import java.io.Writer; public class Main {
public static void main(String[] args) throws Exception { Writer writer = null; String text = "This is a text file"; File file = new File("write.txt"); writer = new BufferedWriter(new FileWriter(file)); writer.write(text); writer.close(); }
}
</source>
Write to file using a BufferedWriter
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; public class Main {
public static void main(String[] args) throws Exception { BufferedWriter bufferedWriter = null; bufferedWriter = new BufferedWriter(new FileWriter("yourFile.txt")); bufferedWriter.write("string"); bufferedWriter.newLine(); bufferedWriter.write("string"); }
}
</source>
Writing to a File: If the file does not exist, it is automatically created.
<source lang="java">
import java.io.BufferedWriter; import java.io.FileWriter; public class Main {
public static void main(String[] argv) throws Exception { BufferedWriter out = new BufferedWriter(new FileWriter("outfilename")); out.write("asdf"); out.close(); }
}
</source>