IT技术 - 访问 this.state 值到其他类 [React Native] - 吾爱随笔录

我只是想问我如何从其他类访问 this.state.sampleString .. 这是我的代码

class MainClass extends Component {

  constructor(props){
      super(props)


      this.state = {
        sampleString: 'Test String'
      }

      this.getValue = this.getValue.bind(this);
    }


    getValue(){
        //console.log(this.state.sampleString);
        return this.state.sampleString
    }

}

==========

这是我的第二个类的函数，用于从 MainClass 获取“this.state.sampleString”的值

function getValueFromMainClass() {

  var stringFromClassHeader = () => {HeaderWithBg.getValue()}

  console.log(stringFromClassHeader.sampleString);

}

为什么它返回“未定义”？

非常感谢。我是 React Native 的新手。

class MainClass extends Component { constructor(props){ super(props) this.state = { sampleString: 'Test String' } this.getValue = this.getValue.bind(this); } getValue(){ //console.log(this.state.sampleString); return this.state.sampleString } render(){ return ( <ChildClass sampleString={this.state.sampleString}/> ) } } class ChildClass extends Component { somefunction() { //console.log(this.props.sampleString); return this.props.sampleString } render(){ return ... } }