file input stream

mkyong · mkyong · commit 42aa05c0e0ff · 2021-01-01T17:16:30.000+08:00
diff --git a/java-io/src/main/java/com/mkyong/io/api/inputstream/FileInputStreamExample.java b/java-io/src/main/java/com/mkyong/io/api/inputstream/FileInputStreamExample.java
@@ -0,0 +1,107 @@
+package com.mkyong.io.api.inputstream;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+
+public class FileInputStreamExample {
+
+    public static void main(String[] args) {
+        String file = "c:\\test\\file.txt";
+        String fileUnicode = "c:\\test\\file-unicode.txt";
+
+        readFile(file);
+        //readFileBetterPerformance(fileUnicode);
+        //readFileBetterInputStreamReader(fileUnicode);
+
+    }
+
+    private static void readFile(String fileName) {
+
+        try (FileInputStream fis = new FileInputStream(new File(fileName))) {
+
+            // remaining bytes that can be read
+            System.out.println("Remaining bytes that can be read : " + fis.available());
+
+            int content;
+            // reads a byte at a time, if end of the file, returns -1
+            while ((content = fis.read()) != -1) {
+                System.out.println((char) content);
+
+                System.out.println("Remaining bytes that can be read : " + fis.available());
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void readFileBetterPerformance(String fileName) {
+
+        try (FileInputStream fis = new FileInputStream(new File(fileName))) {
+
+            // remaining bytes that can be read
+            System.out.println("Remaining bytes that can be read : " + fis.available());
+
+            // 8k a time
+            byte[] bytes = new byte[8192];
+
+            // reads 8192 bytes at a time, if end of the file, returns -1
+            while (fis.read(bytes) != -1) {
+
+                // convert bytes to string for demo
+                // also convert unicode to string
+                System.out.println(new String(bytes, StandardCharsets.UTF_8));
+
+                System.out.println("Remaining bytes that can be read : " + fis.available());
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void readFileBetterPerformance2(String fileName) {
+
+        try (BufferedInputStream bis =
+                     new BufferedInputStream(
+                             new FileInputStream(new File(fileName)))) {
+
+            // remaining bytes that can be read
+            System.out.println("Remaining bytes that can be read : " + bis.available());
+
+            int content;
+            // reads 8192 bytes at a time and buffers them until they are needed,
+            // if end of the file, returns -1
+            while ((content = bis.read()) != -1) {
+
+                // convert bytes to string for demo
+                System.out.println((char) content);
+
+                System.out.println("Remaining bytes that can be read : " + bis.available());
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void readFileBetterInputStreamReader(String fileName) {
+
+        try (BufferedReader br =
+                     new BufferedReader(
+                             new InputStreamReader(
+                                     new FileInputStream(new File(fileName))))) {
+
+            String line;
+            while ((line = br.readLine()) != null) {
+                System.out.println(line);
+            }
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+
+}
diff --git a/java-io/src/main/java/com/mkyong/io/examples/FileInputStreamReadFile.java b/java-io/src/main/java/com/mkyong/io/examples/FileInputStreamReadFile.java
diff --git a/java-io/src/main/java/com/mkyong/io/howto/InputStreamToString.java b/java-io/src/main/java/com/mkyong/io/howto/InputStreamToString.java
@@ -18,7 +18,7 @@ public static void main(String[] args) throws IOException {
         try (InputStream inputStream = uri.toURL().openStream()) {
 
             // InputStream -> String
-            String result = convertInputStreamToStringInputStreamReader(inputStream);
+            String result = convertInputStreamToString(inputStream);
             System.out.println(result);
 
         }

Original file line number	Diff line number	Diff line change
`@@ -18,7 +18,7 @@ public static void main(String[] args) throws IOException {`
`18`	`18`	`try (InputStream inputStream = uri.toURL().openStream()) {`
`19`	`19`
`20`	`20`	`// InputStream -> String`
`21`		`- String result = convertInputStreamToStringInputStreamReader(inputStream);`
	`21`	`+ String result = convertInputStreamToString(inputStream);`
`22`	`22`	`System.out.println(result);`
`23`	`23`
`24`	`24`	`}`