class Banana extends React.Component {
  constructor() {
    super();
    this.state = {};

    this.handleChange = this.handleChange.bind(this);
    this.clearSelected = this.clearSelected.bind(this);
  }

  handleChange(value) {
    this.setState({ selected: value });
  }

  clearSelected() {
    this.setState({ selected: null });
  }

  render() {
    return (
      <div>
        <Select value={this.state.selected} style={{ width: 120 }} onChange={this.handleChange}>
          <Option value="jack">Jack</Option>
          <Option value="lucy">Lucy</Option>
          <Option value="disabled" disabled>Disabled</Option>
          <Option value="Yiminghe">yiminghe</Option>
        </Select>
        <Button onClick={this.clearSelected}>clear selected</Button>
      </div>
    );
  }
}