Java Tutorial/Development/Java Compiler

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Compile Java file

   <source lang="java">

import javax.tools.Diagnostic; import javax.tools.DiagnosticCollector; import javax.tools.JavaCompiler; import javax.tools.JavaFileObject; import javax.tools.StandardJavaFileManager; import javax.tools.ToolProvider; public class CompileFiles2 {

 public static void main(String[] args) {
   JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
   DiagnosticCollector<JavaFileObject> dc;
   dc = new DiagnosticCollector<JavaFileObject>();
   StandardJavaFileManager sjfm;
   sjfm = compiler.getStandardFileManager(dc, null, null);
   Iterable<? extends JavaFileObject> fileObjects;
   fileObjects = sjfm.getJavaFileObjects(args);
   compiler.getTask(null, sjfm, dc, null, null, fileObjects).call();
   for (Diagnostic d : dc.getDiagnostics()) {
     System.out.println(d.getMessage(null));
     System.out.printf("Line number = %d\n", d.getLineNumber());
     System.out.printf("File = %s\n", d.getSource());
   }
 }

}</source>





Compiler Info

   <source lang="java">

import java.util.Set; import javax.lang.model.SourceVersion; import javax.tools.JavaCompiler; import javax.tools.ToolProvider; public class CompilerInfo {

 public static void main(String[] args) {
   JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
   System.out.println("Supported source versions:");
   Set<SourceVersion> srcVer = compiler.getSourceVersions();
   for (SourceVersion sv : srcVer)
     System.out.println("  " + sv.name());
   int nargs = compiler.isSupportedOption(args[0]);
   if (nargs == -1)
     System.out.println("Option " + args[0] + " is not supported");
   else
     System.out.println("Option " + args[0] + " takes " + nargs + " arguments");
 }

}</source>





Compile String

   <source lang="java">

import java.lang.reflect.Method; import java.net.URI; import java.util.Iterator; import java.util.NoSuchElementException; import javax.tools.JavaCompiler; import javax.tools.JavaFileObject; import javax.tools.SimpleJavaFileObject; import javax.tools.ToolProvider; public class CompileString {

 public static void main(String[] args) throws Exception {
   JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
   String program = "class Test{" + "   public static void main (String [] args){"
       + "      System.out.println (\"Hello, World\");"
       + "      System.out.println (args.length);" + "   }" + "}";
   Iterable<? extends JavaFileObject> fileObjects;
   fileObjects = getJavaSourceFromString(program);
   compiler.getTask(null, null, null, null, null, fileObjects).call();
   Class<?> clazz = Class.forName("Test");
   Method m = clazz.getMethod("main", new Class[] { String[].class });
   Object[] _args = new Object[] { new String[0] };
   m.invoke(null, _args);
 }
 static Iterable<JavaSourceFromString> getJavaSourceFromString(String code) {
   final JavaSourceFromString jsfs;
   jsfs = new JavaSourceFromString("code", code);
   return new Iterable<JavaSourceFromString>() {
     public Iterator<JavaSourceFromString> iterator() {
       return new Iterator<JavaSourceFromString>() {
         boolean isNext = true;
         public boolean hasNext() {
           return isNext;
         }
         public JavaSourceFromString next() {
           if (!isNext)
             throw new NoSuchElementException();
           isNext = false;
           return jsfs;
         }
         public void remove() {
           throw new UnsupportedOperationException();
         }
       };
     }
   };
 }

} class JavaSourceFromString extends SimpleJavaFileObject {

 final String code;
 JavaSourceFromString(String name, String code) {
   super(URI.create("string:///" + name.replace(".", "/") + Kind.SOURCE.extension), Kind.SOURCE);
   this.code = code;
 }
 public CharSequence getCharContent(boolean ignoreEncodingErrors) {
   return code;
 }

}</source>





Enum Alternate Java Compilers

   <source lang="java">

import java.util.ServiceLoader; import javax.tools.JavaCompiler; public class EnumAlternateJavaCompilers {

 public static void main(String[] args) {
   ServiceLoader<JavaCompiler> compilers;
   compilers = ServiceLoader.load(JavaCompiler.class);
   System.out.println(compilers.toString());
   for (JavaCompiler compiler : compilers)
     System.out.println(compiler);
 }

}</source>





Get classpath using System class

   <source lang="java">

public class Main {

 public static void main(String[] args) {
   System.out.println(System.getProperty("java.class.path"));
 }

}</source>





JavaCompiler.run to compile

   <source lang="java">

import javax.tools.JavaCompiler; import javax.tools.ToolProvider; public class CompileFiles1 {

 public static void main(String[] args) {
   JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
   compiler.run(null, null, null, args);
 }

}</source>





Programmatically compile Java class

   <source lang="java">

import javax.tools.JavaCompiler; import javax.tools.ToolProvider; public class Main {

 public static void main(String[] args) {
   JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
   int result = compiler.run(null, null, null, "Hello.java");
   System.out.println("Compile result code = " + result);
 }

}</source>