hashMap put的返回值测试

@Test
public void findOne() throws Exception {
    HashMap<Integer,Integer> hashMap = new HashMap<>(  );
    log.info( "sunzhuo" );
    log.info( String.valueOf( hashMap.put( 1,2 ) ) );
    log.info( String.valueOf( hashMap.put( 1,2 ) ) );
    log.info( String.valueOf( hashMap.put( 1,3 ) ) );
    log.info( String.valueOf( hashMap.put( 1,3 ) ) );
    log.info( String.valueOf( hashMap ) );
    log.info( "sunzhuo" );

}

2017-12-18 18:28:36,275 - sunzhuo
2017-12-18 18:28:36,275 - null
2017-12-18 18:28:36,275 - 2
2017-12-18 18:28:36,275 - 2
2017-12-18 18:28:36,275 - 3
2017-12-18 18:28:36,275 - {1=3}
2017-12-18 18:28:36,275 - sunzhuo

还是自己写测试快。