关于泛型介于返回值同static之间的意义

直接放出代码, 很简单

@Test
public void getGenericTest1() {
    String str = getObject("string");
    AssertUtils.assertEquals(str, "字符串", "结果错误");
}
@Test
public void getGenericTest2() {
    boolean b = getObject("boolean");
    AssertUtils.assertTrue(b, "结果错误");
}
@Test
public void getGenericTest3() {
    User user = getObject("user");
    AssertUtils.assertNotNull(user, "结果为null");
}

@SuppressWarnings("unchecked")
public static <E> E getObject(String key) {
    Map<String, Object> r = new HashMap<String, Object>();
    // 放几种不同类型的数据进行测试用
    r.put("string", "字符串");
    r.put("boolean", false);
    r.put("user", new User());
    for (Map.Entry<String, Object> entry: r.entrySet()) {
        if (key.equals(entry.getKey())) {
            return (E) entry.getValue();
        }
    }
    return null;
}