Question

有人可以解释为什么我在这里没有得到预期的结果吗？

const initialState = {
  items: ['cats'],
};

const reducer = (state = initialState) => {
  return {
    ...state,
    items: state.items.push('dogs'),
  };
};

console.log(reducer()); // { items: 2 }

预期结果：{ items: ['cats', 'dogs'] }
实际结果：{ items: 2 }

PS：我想我在js / redux上跳过了这门课程，否则我的大脑不再起作用了。

Answer 1

您直接用const reducer = (state = initialState) => { return { ...state, items: [...state.items, 'dogs'], }; };来改变状态，而是使用数组扩展：

private lateinit var customTitle: AppCompatTextView

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    // stuff here
    customTitle = createCustomTitleTextView()
    // other stuff here
}

private fun createCustomTitleTextView(): AppCompatTextView {
    val mTitleTextView = AppCompatTextView(this)
    TextViewCompat.setTextAppearance(mTitleTextView, R.style.your_style_or_null);

    val layoutParams = ActionBar.LayoutParams(
        ActionBar.LayoutParams.WRAP_CONTENT,
        ActionBar.LayoutParams.WRAP_CONTENT
    )
    layoutParams.gravity = Gravity.CENTER
    supportActionBar?.setCustomView(mTitleTextView, layoutParams)
    supportActionBar?.displayOptions = ActionBar.DISPLAY_SHOW_CUSTOM

    return mTitleTextView
}

override fun setTitle(title: CharSequence?) {
    customTitle.text = title
}

override fun setTitle(titleId: Int) {
    customTitle.text = getString(titleId)
}

还原到状态

1 个答案: