Added examples related to FileReader, FileWriter, BufferReader,

BufferWriter, and PrintWriter

Author: bhuwang

file1.txt

@@ -0,0 +1,3 @@
+one 
+two
+three

file2.txt

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+four
+five
+six

file3.txt

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+one 
+four
+two
+five
+three
+six

file_writer_demo.txt

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+B100
+true
+10.2
+Bhuwan

src/com/bhuwan/java/io/file/BufferedReaderDemo.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class BufferedReaderDemo {
+
+    /**
+     * @param args
+     * @throws IOException
+     */
+    public static void main(String[] args) throws IOException {
+        try (BufferedReader br = new BufferedReader(new FileReader("file_writer_demo.txt"));) {
+            String line = br.readLine();
+            while (line != null) {
+                System.out.println(line);
+                line = br.readLine();
+            }
+        } catch (Exception e) {
+
+        }
+    }
+
+}

src/com/bhuwan/java/io/file/BufferedWriterDemo.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.BufferedWriter;
+import java.io.FileWriter;
+import java.io.IOException;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class BufferedWriterDemo {
+
+    /**
+     * @param args
+     * @throws IOException
+     */
+    public static void main(String[] args) throws IOException {
+        try (BufferedWriter bw = new BufferedWriter(new FileWriter("file_writer_demo.txt", true));
+                BufferedWriter bw1 = new BufferedWriter(new FileWriter("file_writer_demo.txt"));
+                // initializing double buffered writer object.
+                BufferedWriter bw2 = new BufferedWriter(new BufferedWriter(new FileWriter("file_writer_demo.txt")));) {
+            bw.write(66);
+            bw.write("huwan");
+            bw.newLine();
+            bw.write("Hello BufferWriter!!");
+            bw.newLine();
+            bw.write(new char[] { 'A', 'B', 'C' });
+            bw.newLine();
+            bw.write('X');
+            bw.newLine();
+            bw.flush();
+        } catch (Exception e) {
+            System.out.println("Inside Exception block.");
+        }
+    }
+
+}

src/com/bhuwan/java/io/file/FileReaderDemo.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class FileReaderDemo {
+
+    /**
+     * @param args
+     * @throws IOException
+     */
+    public static void main(String[] args) throws IOException {
+        System.out.println("----------------------------------------------");
+        System.out.println("Reading file using read() method.");
+        System.out.println("----------------------------------------------");
+        FileReader fr = new FileReader("file_writer_demo.txt");
+        int read = fr.read();
+        while (read != -1) {
+            System.out.print((char) read);
+            read = fr.read();
+        }
+
+        // reading file using read(ch) method
+        System.out.println();
+        System.out.println("----------------------------------------------");
+        System.out.println("Reading file using read(ch) method.");
+        System.out.println("----------------------------------------------");
+        File file = new File("file_writer_demo.txt");
+        char[] chars = new char[(int) file.length()];
+        FileReader fileReader = new FileReader(file);
+        fileReader.read(chars);
+        for (char c : chars) {
+            System.out.print(c);
+        }
+        fileReader.close();
+        fr.close();
+    }
+
+}

src/com/bhuwan/java/io/file/FileWriterDemo.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class FileWriterDemo {
+
+    /**
+     * @param args
+     * @throws IOException
+     */
+    public static void main(String[] args) throws IOException {
+        try (
+                // FileWriter fw = new FileWriter("file_writer_demo.txt");
+                FileWriter fw = new FileWriter("file_writer_demo.txt", true);) {
+            fw.write(66);
+            fw.write("huwan");
+            fw.write("\n");
+            fw.write("Hello FileWriter!!");
+            fw.write("\n");
+            fw.write(new char[] { 'A', 'B', 'C' });
+            fw.write("\n");
+            fw.write('X');
+            fw.write("\n");
+            fw.flush();
+        } catch (Exception e) {
+            System.out.println("Inside Exception block.");
+        }
+    }
+
+}

src/com/bhuwan/java/io/file/MergeDataFromTwoFilestoSingleFile.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.PrintWriter;
+
+/**
+ * Read data from two files file1.txt and file2.txt and write to file3.txt.
+ * 
+ * @author bhuwan
+ *
+ */
+public class MergeDataFromTwoFilestoSingleFile {
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) {
+        try (PrintWriter pw = new PrintWriter("file3.txt"); BufferedReader br = new BufferedReader(new FileReader("file1.txt"));
+                BufferedReader br2 = new BufferedReader(new FileReader("file2.txt"));) {
+            // read from file1
+            String line = br.readLine();
+            while (line != null) {
+                pw.println(line);
+                line = br.readLine();
+            }
+
+            // read from file2
+            line = br2.readLine();
+            while (line != null) {
+                pw.println(line);
+                line = br2.readLine();
+            }
+            pw.flush();
+        } catch (Exception e) {
+            System.out.println("Inside exception catch block.");
+        }
+    }
+
+}

src/com/bhuwan/java/io/file/MergeDataFromTwoFilestoSingleFileAlternatively.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.PrintWriter;
+
+/**
+ * <pre>
+ * Read data from two files file1.txt and file2.txt and write to file3.txt where write to file should be done alternatively. 
+ * Steps:
+ * 1. read first line from file1 and write to file3
+ * 2. read first line from file2 and write to file3
+ * 3. read second line from file1 and write to file3
+ * 4. read second line from file2 and write to file3
+ * and so on.........
+ * </pre>
+ * 
+ * @author bhuwan
+ *
+ */
+public class MergeDataFromTwoFilestoSingleFileAlternatively {
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) {
+        try (PrintWriter pw = new PrintWriter("file3.txt"); BufferedReader br = new BufferedReader(new FileReader("file1.txt"));
+                BufferedReader br2 = new BufferedReader(new FileReader("file2.txt"));) {
+
+            // read from file1
+            String line1 = br.readLine();
+            // read from file2
+            String line2 = br2.readLine();
+            while (line1 != null || line2 != null) {
+                if (line1 != null) {
+                    pw.println(line1);
+                    line1 = br.readLine();
+                }
+                if (line2 != null) {
+                    pw.println(line2);
+                    line2 = br2.readLine();
+                }
+            }
+            pw.flush();
+        } catch (Exception e) {
+            System.out.println("Inside exception catch block.");
+        }
+    }
+
+}

src/com/bhuwan/java/io/file/PrintWriterDemo.java

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+/**
+ * 
+ */
+package com.bhuwan.java.io.file;
+
+import java.io.PrintWriter;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class PrintWriterDemo {
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) {
+        try (PrintWriter pw = new PrintWriter("file_writer_demo.txt");) {
+            // will write B to the file, since PrintWriter using write method.
+            pw.write(66);
+            // will write 100 directly to the file.
+            pw.println(100);
+            pw.println(true);
+            pw.println(10.2);
+            pw.println("Bhuwan");
+            pw.flush();
+        } catch (Exception e) {
+            System.out.println("Inside exception catch block.");
+        }
+
+    }
+
+}