public static void main(String[] args) {
String[] arr = new String[3];
List<String> list = new ArrayList<String>();
if (list instanceof Collection) System.out.println("" + "true");
else System.out.println("" + "false");
System.out.println(arr.getClass());
System.out.println(list.getClass());
}
public static void main(String[] args) {
List<Frob> list = new ArrayList<Frob>();
Map<Frob, Fnorkle> map = new HashMap<Frob, Fnorkle>();
Quark<Fnorkle> quark = new Quark<Fnorkle>();
Particle<Long, Double> p = new Particle<Long, Double>();
System.out.println(Arrays.toString(list.getClass().getTypeParameters()));
System.out.println(Arrays.toString(map.getClass().getTypeParameters()));
System.out.println(Arrays.toString(quark.getClass().getTypeParameters()));
System.out.println(Arrays.toString(p.getClass().getTypeParameters()));
}
public void show() {
System.out.println(cid);
System.out.println(cname);
System.out.println(email);
System.out.println(phone);
System.out.println(emails);
System.out.println(phones);
System.out.println(refs);
System.out.println(myprops);
System.out.println(address);
for (Account acc : accounts) {
System.out.println(acc);
}
System.out.println(emails.getClass().getName());
System.out.println(phones.getClass().getName());
System.out.println(myprops.getClass().getName());
}
private <E> Object executeForMany(SqlSession sqlSession, Object[] args) {
List<E> result;
Object param = method.convertArgsToSqlCommandParam(args);
if (method.hasRowBounds()) {
RowBounds rowBounds = method.extractRowBounds(args);
result = sqlSession.<E>selectList(command.getName(), param, rowBounds);
} else {
result = sqlSession.<E>selectList(command.getName(), param);
}
// issue #510 Collections & arrays support
if (!method.getReturnType().isAssignableFrom(result.getClass())) {
if (method.getReturnType().isArray()) {
return convertToArray(result);
} else {
return convertToDeclaredCollection(sqlSession.getConfiguration(), result);
}
}
return result;
}
/**
* ArrayList<String>和ArrayList<Integer>很容易认为是不同的类型， 不同的类型在行为方面肯定不同 但输出发现c1==c2为true
*
* @param args
*/
public static void main(String[] args) {
Class c1 = new ArrayList<String>().getClass();
Class c2 = new ArrayList<Integer>().getClass();
System.out.println(c1 == c2); // 输出为true
List<Frob> list = new ArrayList<Frob>();
Map<Frob, Fnorkle> map = new HashMap<Frob, Fnorkle>();
Quark<Fnorkle> quark = new Quark<Fnorkle>();
Particle<Long, Double> part = new Particle<Long, Double>();
// Class.getTypeParameters()将返回一个Typeariable对象数组，表示有泛型声明
// 的类型参数...
System.out.println(Arrays.toString(list.getClass().getTypeParameters()));
System.out.println(Arrays.toString(map.getClass().getTypeParameters()));
System.out.println(Arrays.toString(quark.getClass().getTypeParameters()));
System.out.println(Arrays.toString(part.getClass().getTypeParameters()));
/** 输出结果： [E] [K, V] [Q] [POSITION, MOMENTUM] */
/**
* 输出结果是一些占位符 说明：在泛型代码内部，无法获得任何有关泛型参数类型的信息。 当你在使用泛型时，任何具体的类型信息都被擦除了，你唯一知道的就是你在使用一个对象。
* 因此，List<String>和List<Integer>在运行时事实上是相同的类型。这两种形式都被 擦除成它们的原生类型，即List
*/
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("[Bean, list ");
if (_beans == null) {
sb.append("NULL");
} else {
sb.append('(').append(_beans.size()).append('/');
sb.append(_beans.getClass().getName()).append(") ");
boolean type = false;
for (CtorValueBean bean : _beans) {
if (!type) {
sb.append("(").append(bean.getClass().getSimpleName()).append(")");
type = true;
}
sb.append(bean);
sb.append(' ');
}
}
sb.append(']');
return sb.toString();
}