我不断收到一条错误消息，说 this.replaceState 不是函数

Question

现在我有一个学校项目要在我的手机上构建一个应用程序。我们正在使用 React Native 和 Java。我想在应用程序中制作一个按钮，按下时会变为随机颜色。然而，这不起作用。

这是我的一些代码片段：

    export default class HomeScreen extends React.Component {

  constructor(props) {

  super(props);

  this.state = {color: "#000000"}

}

  render() {

    let color = this.state.color;

  return (

...

<View>

          <Button

          onPress = {changecolor}

          title = "This button changes color when pressed"

          color = {color}/>

        </View>

...

numbers = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"];

this.random = this.numbers[Math.floor(Math.random() * this.numbers.length)];

function changecolor() {

  this.replaceState({color: String("#"+random+random+random+random+random+random)});

} 

在此之前我也遇到了一个问题，该按钮只会变成灰色阴影而不是任何颜色。请问有什么帮助吗？

编辑：我应该提到我之前使用过 this.setState 并且结果相同

Answer 1

export default class HomeScreen extends React.Component {&nbsp; &nbsp; constructor(props) {&nbsp; &nbsp; &nbsp; &nbsp; super(props);&nbsp; &nbsp; &nbsp; &nbsp; this.state = {color: "#000000"}&nbsp; &nbsp; }&nbsp; &nbsp; render() {&nbsp; &nbsp; let color = this.state.color;&nbsp; &nbsp; return (&nbsp; &nbsp; <View>&nbsp; &nbsp; &nbsp; &nbsp; <Button&nbsp; &nbsp; &nbsp; &nbsp; onPress = {this.changecolor}&nbsp; &nbsp; &nbsp; &nbsp; title = "This button changes color when pressed"&nbsp; &nbsp; &nbsp; &nbsp; color = {color}/>&nbsp; &nbsp; </View>&nbsp; &nbsp; numbers = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"];&nbsp; &nbsp; this.random = this.numbers[Math.floor(Math.random() * this.numbers.length)];&nbsp; &nbsp; changecolor() {&nbsp; &nbsp; &nbsp; &nbsp; this.replaceState({color: String("#"+random+random+random+random+random+random)});&nbsp; &nbsp; }}&nbsp;

Answer 2

changecolor甚至是班级成员HomeScreen？看起来不像，考虑到它是用声明的function并且没有解析错误对你大喊大叫。让它成为一个方法，更好的是，一个箭头函数：changecolor = () => {&nbsp; this.replaceState({color: String("#"+random+random+random+random+random+random)});}&nbsp;