title: How to set checkbox component checked in Material-UI React?
body: <p>As the title,<br>
  I want to set checkbox "checked" by default when the page was fully load,<br>
  but in the tutorial about <a href="https://material-ui.com/api/checkbox/" rel="nofollow noreferrer">Material-UI Checkbox component</a>,
  didn't have the <code>defaultChecked</code> props.<br>
  When I add <code>checked={true}</code> props, then get arror
  like <br>"A component is changing an uncontrolled input of type checkbox to be controlled...etc"<br>
  How should I do?</p>
  
  <p>there is my code<br>
  I want to list all the group, include the default group and the other
  let the user to choose multi group.</p>
  
  <pre><code>  export default class AcceptButton extends Component {
    constructor(props) {
      super(props)
      this.handleChange = this.handleChange.bind(this)
      this.state = {open: true}
    }
    handleChange = event =&gt; {
      this.setState({checked: event.target.checked})
    }
    render() {
      return (
        &lt;Fragment&gt;
         &lt;div&gt;
           group : 
         &lt;/div&gt;
         &lt;div className="f-col"&gt;
         {
          group.data.map(g =&gt; {
            if (data.filter(d =&gt; d.gid == g.gid).length != 0) {
              return (
                &lt;FormControlLabel
                  key={g.gid}
                  control={
                    &lt;Checkbox
                      disabled={true}
                      onChange = {this.handleChange}
                      color="primary"
                      checked={this.state.open}
                    /&gt;
                  }
                  label={g.gname}
                /&gt;
            )}
            else {
              return (
                &lt;FormControlLabel
                  key={g.gid}
                  control={
                    &lt;Checkbox
                      onChange={this.handleChange}
                      value={g.gname}
                      color="primary"
                    /&gt;
                  }
                  label={g.gname}
                /&gt;
            )}
          })
        }
      &lt;/div&gt; 
      &lt;button className="btn" onClick={this.postassignhandle}&gt;update&lt;/button&gt;
    &lt;/Fragment&gt;
  )
  </code></pre>