Admin: 1 версия

2010-06-01T06:04:29Z

1 версия

в 18:01, 31 мая 2010

2010-05-31T18:01:43Z

Новая страница

== Check the class version ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
DataInputStream in = new DataInputStream(new FileInputStream("Main.class"));
int start = in.readInt();
if (start != 0xcafebabe) {
System.out.println("not valid");
}
in.close();
System.out.println(in.readUnsignedShort()+"/"+in.readUnsignedShort());

}
}

</source>



== Create DataInputStream from FileInputStream and read different types of data ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
class DataInputStreamDemo {
public static void main(String args[]) throws Exception {
FileInputStream fis = new FileInputStream(args[0]);
DataInputStream dis = new DataInputStream(fis);
System.out.println(dis.readBoolean());
System.out.println(dis.readByte());
System.out.println(dis.readChar());
System.out.println(dis.readDouble());
System.out.println(dis.readFloat());
System.out.println(dis.readInt());
System.out.println(dis.readLong());
System.out.println(dis.readShort());
fis.close();
}
}

</source>



== DataOutputStream and DataInputStream: read and write by data types ==



<source lang="java">

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] atgs) throws Exception {
DataOutputStream out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("java.txt")));
out.writeUTF("");
out.writeBytes("a");
out.writeChars("aaa");
out.close();
DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream("java.txt")));
System.out.println(in.readUTF());
byte[] buf = new byte[1024];
int len = in.read(buf);
System.out.println(new String(buf, 0, len));
in.close();
}
}

</source>



== new DataInputStream(new BufferedInputStream(new FileInputStream())) ==



<source lang="java">

/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataStreams {
static final String dataFile = "invoicedata";
static final double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
static final int[] units = { 12, 8, 13, 29, 50 };
static final String[] descs = { "Java T-shirt", "Java Mug",
"Duke Juggling Dolls", "Java Pin", "Java Key Chain" };
public static void main(String[] args) throws IOException {
DataOutputStream out = null;
try {
out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
dataFile)));
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeInt(units[i]);
out.writeUTF(descs[i]);
}
} finally {
out.close();
}
DataInputStream in = null;
double total = 0.0;
try {
in = new DataInputStream(new BufferedInputStream(new FileInputStream(
dataFile)));
double price;
int unit;
String desc;
try {
while (true) {
price = in.readDouble();
unit = in.readInt();
desc = in.readUTF();
System.out.format("You ordered %d units of %s at $%.2f%n", unit,
desc, price);
total += unit * price;
}
} catch (EOFException e) {
}
System.out.format("For a TOTAL of: $%.2f%n", total);
} finally {
in.close();
}
}
}

</source>



== Read boolean from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/n.txt");
DataInputStream din = new DataInputStream(fin);
boolean b = din.readBoolean();
System.out.println("boolean : " + b);
din.close();
}
}

</source>



== Read byte array from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Array.txt");
DataInputStream din = new DataInputStream(fin);
byte b[] = new byte[10];
din.read(b);
din.close();
}
}

</source>



== Read byte from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Byte.txt");
DataInputStream din = new DataInputStream(fin);
byte b = din.readByte();
System.out.println("byte : " + b);
din.close();
}
}

</source>



== Read char from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception{
FileInputStream fin = new FileInputStream("C:/Char.txt");
DataInputStream din = new DataInputStream(fin);
char ch = din.readChar();
System.out.println("Char : " + ch);
din.close();
}
}

</source>



== Read different data types from DataInputStream ==



<source lang="java">

/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataStreams {
static final String dataFile = "invoicedata";
static final double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
static final int[] units = { 12, 8, 13, 29, 50 };
static final String[] descs = { "Java T-shirt", "Java Mug",
"Duke Juggling Dolls", "Java Pin", "Java Key Chain" };
public static void main(String[] args) throws IOException {
DataOutputStream out = null;
try {
out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
dataFile)));
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeInt(units[i]);
out.writeUTF(descs[i]);
}
} finally {
out.close();
}
DataInputStream in = null;
double total = 0.0;
try {
in = new DataInputStream(new BufferedInputStream(new FileInputStream(
dataFile)));
double price;
int unit;
String desc;
try {
while (true) {
price = in.readDouble();
unit = in.readInt();
desc = in.readUTF();
System.out.format("You ordered %d units of %s at $%.2f%n", unit,
desc, price);
total += unit * price;
}
} catch (EOFException e) {
}
System.out.format("For a TOTAL of: $%.2f%n", total);
} finally {
in.close();
}
}
}

</source>



== Read double from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/read.txt");
DataInputStream din = new DataInputStream(fin);
double d = din.readDouble();
System.out.println("Double : " + d);
din.close();
}
}

</source>



== Read float from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Float.txt");
DataInputStream din = new DataInputStream(fin);
float f = din.readFloat();
System.out.println("float : " + f);
din.close();
}
}

</source>



== Read int from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Int.txt");
DataInputStream din = new DataInputStream(fin);
int i = din.readInt();
System.out.println("int : " + i);
din.close();
}
}

</source>



== Read long from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Long.txt");
DataInputStream din = new DataInputStream(fin);
long l = din.readLong();
System.out.println("long : " + l);
din.close();
}
}

</source>



== Read short from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Short.txt");
DataInputStream din = new DataInputStream(fin);
short s = din.readShort();
System.out.println("short : " + s);
din.close();
}
}

</source>



== Read short type of data with DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
class Main {
public static void main(String args[]) throws Exception {
FileInputStream fis = new FileInputStream(args[0]);
DataInputStream dis = new DataInputStream(fis);
// Read and display data
System.out.print(dis.readShort() + " ");
fis.close();
}
}

</source>



== Read unsigned byte from file using DataInputStream ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/UnsignedByte.txt");
DataInputStream din = new DataInputStream(fin);
int i = din.readUnsignedByte();
System.out.println("Unsinged byte value : " + i);
din.close();
}
}

</source>



== Use DataInputStream to create double ==



<source lang="java">

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] argv) throws Exception {
FileInputStream fileIn = new FileInputStream("data.txt");
DataInputStream dataIn = new DataInputStream(fileIn);
System.out.println(dataIn.readUTF());
int counter = dataIn.readInt();
double sum = 0.0;
for (int i = 0; i < counter; i++) {
double current = dataIn.readDouble();
System.out.println("Just read " + current);
sum += current;
}
System.out.println("\nAverage = " + sum / counter);
dataIn.close();
fileIn.close();
}
}

</source>

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Java/File Input Output/DataInputStream - История изменений

Admin: 1 версия

в 18:01, 31 мая 2010