append file

mkyong · mkyong · commit 189f2b5d4d88 · 2020-10-01T16:28:06.000+08:00
diff --git a/java-io/src/main/java/com/mkyong/io/file/FileAppend.java b/java-io/src/main/java/com/mkyong/io/file/FileAppend.java
@@ -0,0 +1,124 @@
+package com.mkyong.io.file;
+
+import org.apache.commons.io.FileUtils;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.List;
+
+// https://mkyong.com/java/how-to-append-content-to-file-in-java/
+public class FileAppend {
+
+    private static final String NEW_LINE = System.lineSeparator();
+
+    public static void main(String[] args) throws IOException {
+
+        //Path path = Paths.get("/home/mkyong/test/abc.txt");
+        appendToFile(path, "hello world" + NEW_LINE);
+
+        /*File file = new File("/home/mkyong/test/abc.txt");
+        appendToFileFileWriter(file, "hello world" + NEW_LINE);
+        System.out.println("Done");*/
+
+    }
+
+    // Java 7
+    private static void appendToFile(Path path, String content) throws IOException {
+
+        // if file not exists throws java.nio.file.NoSuchFileException
+        //  Files.write(path, content.getBytes(StandardCharsets.UTF_8), StandardOpenOption.APPEND);
+
+        // if file not exists, create it otherwise append to the end of the file
+        Files.write(path, content.getBytes(StandardCharsets.UTF_8),
+                StandardOpenOption.CREATE,
+                StandardOpenOption.APPEND);
+
+    }
+
+
+    // append lines of text
+    private static void appendToFileJava8(Path path, List<String> list) throws IOException {
+
+        // Java 7?
+        // Files.write(path, list, StandardCharsets.UTF_8,
+        //        StandardOpenOption.CREATE,
+        //        StandardOpenOption.APPEND);
+
+        // Java 8, default utf_8
+        Files.write(path, list,
+                StandardOpenOption.CREATE,
+                StandardOpenOption.APPEND);
+
+    }
+
+    // Java 11, writeString, append mode
+    private static void appendToFileJava11(Path path, String content) throws IOException {
+
+        // utf_8
+        // Files.writeString(path, content, StandardCharsets.UTF_8,
+        //        StandardOpenOption.CREATE,
+        //        StandardOpenOption.APPEND);
+
+        // default StandardCharsets.UTF_8
+        Files.writeString(path, content,
+                StandardOpenOption.CREATE,
+                StandardOpenOption.APPEND);
+    }
+
+    private static void appendToFileFileWriter(File file, String content) throws IOException {
+
+        // default - create and write
+        // if file not exists, create and write
+        // if file exists, truncate and write
+        /*try (FileWriter fw = new FileWriter(file);
+             BufferedWriter bw = new BufferedWriter(fw)) {
+            bw.write(content);
+            bw.newLine();
+        }*/
+
+        // append
+        // if file not exists, create and write
+        // if file is exists, append to the end of the file
+        try (FileWriter fw = new FileWriter(file, true);
+             BufferedWriter bw = new BufferedWriter(fw)) {
+            bw.write(content);
+            bw.newLine();   // add new line, System.lineSeparator()
+        }
+
+    }
+
+    private static void appendToFileFileWriter(File file, List<String> content) throws IOException {
+
+        try (FileWriter fw = new FileWriter(file, true);
+             BufferedWriter bw = new BufferedWriter(fw)) {
+
+            for (String s : content) {
+                bw.write(s);
+                bw.newLine();
+            }
+        }
+
+    }
+
+    private static void appendToFileFileOutputStream(File file, String content) throws IOException {
+
+        // append mode
+        try (FileOutputStream fos = new FileOutputStream(file, true)) {
+            fos.write(content.getBytes(StandardCharsets.UTF_8));
+        }
+
+    }
+
+    // append mode
+    private static void appendToFileFileUtils(File file, String content) throws IOException {
+
+        FileUtils.writeStringToFile(
+                file, content, StandardCharsets.UTF_8, true);
+
+    }
+
+
+}
