Typical I/O stream configurations
// : c12:IOStreamDemo.java
// Typical I/O stream configurations.
// {RunByHand}
// {Clean: IODemo.out,Data.txt,rtest.dat}
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.io.StringReader;
public class IOStreamDemo {
// Throw exceptions to console:
public static void main(String[] args) throws IOException {
// 1. Reading input by lines:
BufferedReader in = new BufferedReader(new FileReader(
"IOStreamDemo.java"));
String s, s2 = new String();
while ((s = in.readLine()) != null)
s2 += s + "\n";
in.close();
// 1b. Reading standard input:
BufferedReader stdin = new BufferedReader(new InputStreamReader(
System.in));
System.out.print("Enter a line:");
System.out.println(stdin.readLine());
// 2. Input from memory
StringReader in2 = new StringReader(s2);
int c;
while ((c = in2.read()) != -1)
System.out.print((char) c);
// 3. Formatted memory input
try {
DataInputStream in3 = new DataInputStream(new ByteArrayInputStream(
s2.getBytes()));
while (true)
System.out.print((char) in3.readByte());
} catch (EOFException e) {
System.err.println("End of stream");
}
// 4. File output
try {
BufferedReader in4 = new BufferedReader(new StringReader(s2));
PrintWriter out1 = new PrintWriter(new BufferedWriter(
new FileWriter("IODemo.out")));
int lineCount = 1;
while ((s = in4.readLine()) != null)
out1.println(lineCount++ + ": " + s);
out1.close();
} catch (EOFException e) {
System.err.println("End of stream");
}
// 5. Storing & recovering data
try {
DataOutputStream out2 = new DataOutputStream(
new BufferedOutputStream(new FileOutputStream("Data.txt")));
out2.writeDouble(3.14159);
out2.writeUTF("That was pi");
out2.writeDouble(1.41413);
out2.writeUTF("Square root of 2");
out2.close();
DataInputStream in5 = new DataInputStream(new BufferedInputStream(
new FileInputStream("Data.txt")));
// Must use DataInputStream for data:
System.out.println(in5.readDouble());
// Only readUTF() will recover the
// Java-UTF String properly:
System.out.println(in5.readUTF());
// Read the following double and String:
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
} catch (EOFException e) {
throw new RuntimeException(e);
}
// 6. Reading/writing random access files
RandomAccessFile rf = new RandomAccessFile("rtest.dat", "rw");
for (int i = 0; i < 10; i++)
rf.writeDouble(i * 1.414);
rf.close();
rf = new RandomAccessFile("rtest.dat", "rw");
rf.seek(5 * 8);
rf.writeDouble(47.0001);
rf.close();
rf = new RandomAccessFile("rtest.dat", "r");
for (int i = 0; i < 10; i++)
System.out.println("Value " + i + ": " + rf.readDouble());
rf.close();
}
} ///:~
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