Java對(duì)象實(shí)例化
JAVA類,只要知道了類名(全名)就可以創(chuàng)建其實(shí)例對(duì)象,通用的方法是直接使用該類提供的構(gòu)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(lái)實(shí)現(xiàn)JAVA類的實(shí)例化。
1、空構(gòu)造方法
如果類有空構(gòu)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(shí)現(xiàn)實(shí)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(); } |
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2、帶參數(shù)構(gòu)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(shí)現(xiàn)實(shí)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(shù)組參數(shù)構(gòu)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(shí)現(xiàn)實(shí)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(); } |
posted on 2014-12-03 13:37 順其自然EVO 閱讀(224) 評(píng)論(0) 編輯 收藏 所屬分類: 測(cè)試學(xué)習(xí)專欄