import com.apple.internal.jobjc.generator.utils.JavaLang.JLCtor; //导入依赖的package包/类
@Override public void writeBeginning(final PrintStream out) {
    out.print(new JLField("private static", JOBJC_CLASSNAME, "instance"));
    out.print(new JLField("private final", JObjCRuntime.class.getName(), "runtime"));

    JLMethod getInstR = new JLMethod("public static", JOBJC_CLASSNAME, "getInstance", "final JObjCRuntime runtime");
    getInstR.body.add("if(runtime == null) throw new NullPointerException(\"runtime\");");
    getInstR.body.add("if(instance == null) instance = new JObjC(runtime);");
    getInstR.body.add("return instance;");
    out.print(getInstR);

    JLMethod getInst = new JLMethod("public static", JOBJC_CLASSNAME, "getInstance");
    getInst.body.add("return getInstance(JObjCRuntime.getInstance());");
    out.print(getInst);

    JLCtor ctor = new JLCtor("private", JOBJC_CLASSNAME, "final JObjCRuntime runtime");
    ctor.body.add("this.runtime = runtime;");
    for (final Framework f : frameworks)
        ctor.body.add("runtime.registerPackage(\"" + f.pkg + "\");");
    out.print(ctor);
}