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>
