add Java version (simple as f...)

README.md

@@ -115,6 +115,14 @@ go build freq01.go
 ./freq01 pg.txt out.txt
 ```
 
+Java
+----
+
+```bash
+javac -d junk src/freq01.java
+java -cp junk freq01 pg.txt out.txt
+```
+
 Rust
 -----
 

mk.cmd

@@ -19,6 +19,9 @@ cl.exe /permissive- /GS /GL /W3 /Gy /Zc:wchar_t /Gm- /O2 /sdl /Zc:inline /fp:pre
 echo === freq01.go
 call go build -o bin\freq01go.exe src\freq01.go
 
+echo === freq01.java
+call javac -d bin\ src\freq01.java
+
 echo === freq01.rs
 cd build\rust
 call cargo build --release --color=never

src/freq01.java

@@ -0,0 +1,59 @@
+import java.io.*;
+import java.util.HashMap;
+
+class freq01 {
+    final static char[] ALPHABET = new char[256];
+
+    static {
+        for (char c = 'a'; c <= 'z'; c++) {
+            ALPHABET[c & 0xFF] = c;
+            ALPHABET[c ^ 0x20] = c;
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (args.length < 2) {
+            System.out.println("Usage: java -cp . freq01 in.txt out.txt");
+            System.exit(1);
+        }
+
+        final HashMap<String, Integer> dict = new HashMap<>(256);
+        final StringBuilder word = new StringBuilder(256);
+        final byte[] buffer = new byte[16 * 1024];
+        try (final BufferedInputStream bis = new BufferedInputStream(new FileInputStream(args[0]))) {
+            for (int read = bis.read(buffer); read > 0; read = bis.read(buffer)) {
+                for (int i = 0; i < read; i++) {
+                    char c = ALPHABET[buffer[i] & 0xFF];
+                    if (c != 0) {
+                        word.append(c);
+                    } else if (word.length() > 0) {
+                        dict.merge(word.toString(), 1, Integer::sum);
+                        word.setLength(0);
+                    }
+                }
+            }
+            if (word.length() > 0) {
+                dict.merge(word.toString(), 1, Integer::sum);
+            }
+        }
+
+        try (final BufferedWriter writer = new BufferedWriter(new FileWriter(args[1]))) {
+            dict.entrySet()
+                    .stream()
+                    .sorted((l, r) -> {
+                        int result = r.getValue().compareTo(l.getValue());
+                        if (result == 0) result = l.getKey().compareTo(r.getKey());
+                        return result;
+                    })
+                    .forEachOrdered((e) -> {
+                        try {
+                            writer.write(e.getValue().toString() + " " + e.getKey());
+                            writer.newLine();
+                        } catch (IOException ioException) {
+                            ioException.printStackTrace();
+                            System.exit(1);
+                        }
+                    });
+        }
+    }
+}