TreeMaker如何编写返回空语句

问题描述

喜欢此代码

public boolean equals(Object o) {
   return null;
}

我想使用treeMaker编写 return null 语句，但是我不知道该怎么做。

解决方法

我在这个问题上犯了一个错误，原始不能返回null。

返回null 语句可以像下面的代码一样修饰

JCTree.JCStatement aNull = treeMaker.Return(treeMaker.Literal(TypeTag.BOT,null));

例如

    public String equal(Object o) {
        return null;
    }

    public JCTree.JCMethodDecl generateEqualMethod(JCTree.JCClassDecl classDecl) {
        JCTree.JCModifiers publicModifier = treeMaker.Modifiers(Flags.PUBLIC);
        JCTree.JCExpression returnType = treeMaker.Ident(names.fromString("java"));
        returnType = treeMaker.Select(returnType,names.fromString("lang"));
        returnType = treeMaker.Select(returnType,names.fromString("String"));
        Name method = names.fromString("equal");
        JCTree.JCExpression ObjectExpr = treeMaker.Ident(names.fromString("java"));
        ObjectExpr = treeMaker.Select(ObjectExpr,names.fromString("lang"));
        ObjectExpr = treeMaker.Select(ObjectExpr,names.fromString("Object"));
        JCTree.JCVariableDecl param = 
        treeMaker.VarDef(treeMaker.Modifiers(Flags.PARAMETER),names.fromString("o"),ObjectExpr,null);
        param.pos = classDecl.pos;
        List<JCTree.JCVariableDecl> params = List.of(param);

        List<JCTree.JCStatement> statement = List.nil();
        JCTree.JCStatement aNull = treeMaker.Return(treeMaker.Literal(TypeTag.BOT,null));
        statement = statement.append(aNull);
        JCTree.JCBlock block = treeMaker.Block(0,statement);
        JCTree.JCMethodDecl methodDecl = treeMaker.MethodDef(publicModifier,method,returnType,List.nil(),params,block,null);
        System.out.println(methodDecl);
        return methodDecl;
    }