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 {

    constructor(props) {

        super(props);

        this.state = {color: "#000000"}

    }

    render() {

    let color = this.state.color;

    return (

    <View>

        <Button

        onPress = {this.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)];

    changecolor() {

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

    }

} 

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 = () => {

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

}