JAVA類，只要知道了類名（全名）就可以創建其實例對象，通用的方法是直接使用該類提供的構造方法，如
NewObject o = new NewObject();
NewObject o = new NewObject("
test");
NewObject o = new NewObject(new String[]{"aaa","bbb"});
除此之外，還可以利用java.lang.Class<T>類來實現JAVA類的實例化。
1、空構造方法
如果類有空構造方法，如下面的類
public class NewObject { String name; public NewObject(String[] name) { this.name = name[0]; System.out.println(“ the object is created!”); } public void write() { System.out.println(this.name); } } |
使用以下代碼可實現實例化：
NewObject no = null; try { no = (NewObject)Class.forName(className).newInstance(); no.write(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } |
字體: 小 中 大 | 上一篇 下一篇 | 打印 | 我要投稿
2、帶參數構造方法
public class NewObject { String name; public NewObject() { System.out.println(“ the object is created!”); } public void write() { System.out.println(“”); } } |
使用以下代碼可實現實例化：
try { no=(NewObject)Class.forName(className).getConstructor(String.class).newInstance(names); //no=(NewObject)Class.forName(className).getConstructor(newObject[]{String.class}).newInstance(names); } catch(IllegalArgumentExceptione) { e.printStackTrace(); } catch(SecurityExceptione) { e.printStackTrace(); } catch(InstantiationExceptione) { e.printStackTrace(); } catch(IllegalAccessExceptione) { e.printStackTrace(); } catch(InvocationTargetExceptione) { e.printStackTrace(); } catch(NoSuchMethodExceptione) { e.printStackTrace(); } catch(ClassNotFoundExceptione) { e.printStackTrace(); } |
3、帶數組參數構造方法
public class NewObject
{
String name;
public NewObject(String name)
{
this.name = name;
System.out.println(“ the object is created!”);
}
public void write()
{
System.out.println(this.name);
}
}
使用以下代碼可實現實例化：
try { Constructor[] cs; cs = Class.forName(className).getConstructors(); Constructor cc = Class.forName(className).getConstructor(String[].class); no = (NewObject)cc.newInstance(new Object[]{names}); } catch (SecurityException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } |