Question

我使用Eclipse Mars编译项目。我的理解是Eclipse正在使用它自己的Java编译器（JDT）来编译Java代码。

如何查找Eclipse编译器的版本，以便告诉其他人我使用的是哪个版本？

Answer 1

ECJ编译器并没有真正独立的版本。

Eclipse Project page上提供的ECJ独立下载编号与Eclipse版本相符（当前Eclipse Neon版本为4.6）。

编译器本身包含在public class MenuActivity extends AppCompatActivity { private RecyclerView recyclerView; private DishesAdapter adapter; private ArrayList<String> arrayList = new ArrayList<>(); private MyPagerAdapter pagerAdapter; private ViewPager viewPager; private TabLayout tabLayout; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_menu); recyclerView = (RecyclerView) findViewById(R.id.recycler_menu); recyclerView.setHasFixedSize(true); LinearLayoutManager horizontalLayoutManagaer = new LinearLayoutManager(MenuActivity.this, LinearLayoutManager.HORIZONTAL, false); recyclerView.setLayoutManager(horizontalLayoutManagaer); arrayList = prepareData(); adapter = new DishesAdapter(MenuActivity.this, arrayList); recyclerView.setAdapter(adapter); recyclerView.addOnItemTouchListener(new RecyclerItemClickListener(MenuActivity.this, new RecyclerItemClickListener.OnItemClickListener() { @Override public void onItemClick(View view, int position) { TextView textView = (TextView) view.findViewById(R.id.tv_name); textView.setTextColor(Color.parseColor("#FFFFFF")); adapter.notifyDataSetChanged(); } })); setupToolbar(); setupViewPager(); setupToolbar(); } private ArrayList<String> prepareData() { ArrayList<String> arrayList = new ArrayList<>(); arrayList.add("Chineese"); arrayList.add("South Indian"); arrayList.add("Mughalai"); arrayList.add("Local streat"); return arrayList; } private void setupViewPager() { final ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager); setupViewPager(viewPager); TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs); tabLayout.setupWithViewPager(viewPager); } private void setupToolbar() { Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); toolbar.setTitle(""); getSupportActionBar().setTitle(""); getSupportActionBar().setDisplayShowHomeEnabled(true); getSupportActionBar().setDisplayHomeAsUpEnabled(false); } private void setupViewPager(ViewPager viewPager) { ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager()); adapter.addFrag(new TabFragment(), "Soup"); adapter.addFrag(new TabFragment(), "Rice"); adapter.addFrag(new TabFragment(), "Breads"); adapter.addFrag(new TabFragment(), "Curry"); viewPager.setAdapter(adapter); } static class ViewPagerAdapter extends FragmentPagerAdapter { private final List<Fragment> mFragmentList = new ArrayList<>(); private final List<String> mFragmentTitleList = new ArrayList<>(); public ViewPagerAdapter(FragmentManager manager) { super(manager); } @Override public Fragment getItem(int position) { return mFragmentList.get(position); } @Override public int getCount() { return mFragmentList.size(); } public void addFrag(Fragment fragment, String title) { mFragmentList.add(fragment); mFragmentTitleList.add(title); } @Override public CharSequence getPageTitle(int position) { return mFragmentTitleList.get(position); } } public class MyPagerAdapter extends FragmentPagerAdapter { private final String[] TITLES = {"Soups", "Rice", "Breads", "Curry"}; final int tabCount; public MyPagerAdapter(FragmentManager fm, int tabCount) { super(fm); this.tabCount = tabCount; } @Override public CharSequence getPageTitle(int position) { return TITLES[position]; } @Override public int getCount() { return TITLES.length; } @Override public Fragment getItem(int position) { if (position == 0) { return InfoFragment.newInstance(position); } else { return InfoFragment.newInstance(position); } } } }插件中，该插件有自己的版本（目前为3.12.0）

Answer 2

我推荐你：

1：How to change JDK version for an Eclipse project

2：changing eclipse's java compiler to jdk7

3：how do I get eclipse to use a different compiler version for Java?

4：http://help.eclipse.org/kepler/index.jsp?topic=%2Forg.eclipse.jst.j2ee.doc.user%2Ftopics%2Ftchangejavalevel.html

Answer 3

您需要先进入Java EE Perspective。为此，转到功能区然后：窗口＆gt;透视＆gt; Open Perspective＆gt;其他＆gt; Java EE。

NB：如果您没有看到这个，那么这意味着您没有安装Java EE透视图：请参阅如何在此处下载：

How to add Java EE perspective to Eclipse

之后，打开Package Explorer。然后右键单击Java Project并选择Properties。在属性窗口中，应该有一个“Project Facets”选项。此页面列出了编译器中所有Facets的版本。然后，您还可以查看Java编译器的版本号。

如果需要更改此设置，请单击“修改项目”。然后，单击要更改它的构面。通过从Facet的名称（Java编译器）旁边的下拉菜单中选择版本来执行此操作。单击“完成”，然后单击“确定”。

希望这有帮助！

Answer 4

将command line用于独立的ECJ：
```
java -jar ecj.jar -version
```

示例：

从https://mvnrepository.com/artifact/org.eclipse.jdt.core.compiler/ecj/4.6.1获取ECJ：

...> java -jar ecj-4.6.1.jar -version
Eclipse Compiler for Java(TM) v20160829-0950, 3.12.1, Copyright IBM Corp 2000, 2015. All rights reserved.

从http://archive.eclipse.org/eclipse/downloads/drops/R-3.8.2-201301310800/#JDTCORE获取ECJ：

...> java -jar ecj-3.8.2.jar -version
Eclipse Compiler for Java(TM) v20130121-145325, 3.8.3, Copyright IBM Corp 2000, 2012. All rights reserved.

（应该注意ECJ版本和已发布的jar名称之间的区别。）

使用JSR-199 api以编程方式执行此操作：

import java.io.File;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
import java.util.ServiceLoader;
import javax.tools.JavaCompiler;

public class CompilerVersion {

    public static void main(String[] args) throws Exception
    {

        // Standalone ECJ from http://repo1.maven.org/maven2/org/eclipse/jdt/ecj/3.13.50/ :
        //jar2classpath("E:\\ecj-3.13.50.jar");

        // Load JDT Core & Compiler jars from installed Eclipse Oxygen 4.7.0:
        String eclipseDir = "D:\\eclipse\\";
        jar2classpath(eclipseDir + "plugins\\org.eclipse.jdt.core_3.13.0.v20170516-1929.jar");
        jar2classpath(eclipseDir + "plugins\\org.eclipse.jdt.compiler.tool_1.2.0.v20170502-0408.jar");

        //Class.forName("org.eclipse.jdt.internal.compiler.tool.EclipseCompiler");

        JavaCompiler compiler = ServiceLoader.load(JavaCompiler.class).iterator().next();

        compiler.getTask(null, null, null, 
                Arrays.asList(new String[] {"-version"}), null, null).call();

    }

    private static void jar2classpath(String jarFilename) throws Exception {
        File file = new File(jarFilename);
        Method method = URLClassLoader.class.getDeclaredMethod("addURL", new Class[]{URL.class});
        method.setAccessible(true);
        method.invoke(ClassLoader.getSystemClassLoader(), new Object[]{file.toURI().toURL()});
    }

}

应输出到stderr：

Eclipse Compiler for Java(TM) v20170516-1929, 3.13.0, Copyright IBM Corp 2000, 2015. All rights reserved.

如何找到Eclipse Java编译器（JDT）的版本？

4 个答案: