如何在codemodel中创建简单的赋值语句？

import com.sun.codemodel.JCodeModel;
import com.sun.codemodel.JExpr;
import com.sun.codemodel.JFieldVar;
import com.sun.codemodel.JMethod;
import com.sun.codemodel.JMod;
import com.sun.codemodel.JType;

JCodeModel codeModel = new JCodeModel();

JType classType = codeModel._class("com.example.MyClass");

JFieldVar field = classType.field(JMod.PRIVATE, codeModel.INT, "myField");
field.init(JExpr.lit(10));  // 为字段赋初值

JMethod method = classType.method(JMod.PUBLIC, codeModel.VOID, "myMethod");
method.body().assign(field, JExpr.lit(20));  // 给字段赋新值

codeModel.build(new File("src/main/java"));