react报错this.setState is not a function

constructor(props){
    super(props);
    this.state = {
        keyword:this.props.match.params.id,
        result:"true",
        _isMounted:true
    };
    this.handleFetch.bind(this)  //看这里
}

constructor(props){
    super(props);
    this.state = {
        keyword:this.props.match.params.id,
        result:"true",
        _isMounted:true
    };
    this.handleFetch=this.handleFetch.bind(this)  //这里一定要写等于
}