observable

可觀察的類setChanged()方法 (Observable Class setChanged() method)

• setChanged() method is available in java.util package.

  setChanged()方法在java.util包中可用。

• setChanged() method is used to set this Observable object status as changed.

  setChanged()方法用于將此Observable對象狀態(tài)設(shè)置為已更改。

• setChanged() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  setChanged()方法是一種非靜態(tài)方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

• setChanged() method does not throw an exception at the time of set changing status.

  setChanged()方法在設(shè)置更改狀態(tài)時不會引發(fā)異常。

Syntax:

句法：

protected void setChanged();

Parameter(s):

參數(shù)：

• It does not accept any parameter.

  它不接受任何參數(shù)。

Return value:

返回值：

The return type of the method is void, it returns nothing.

該方法的返回類型為void ，不返回任何內(nèi)容。

Example:

例：

// Java program to demonstrate the example // of void setChanged() method of Observableimport java.util.*;// Implement Observers class class Observers implements Observer {public void update(Observable obj, Object ob) {System.out.println("Obs is added");} }// Implement Observed Class class Observed extends Observable {// Function call with setChanged()void setChange() {setChanged();System.out.println("setChanged(): " + hasChanged());notifyObservers();}// Function call without setChanged()void unsetChange() {System.out.println("unsetChanged(): " + hasChanged());notifyObservers();} }public class SetChanged {// Implement Main Methodpublic static void main(String args[]) {Observed observed = new Observed();Observers obs = new Observers();observed.addObserver(obs);observed.setChange();observed.unsetChange();} }

Output

輸出量

setChanged(): true Obs is added unsetChanged(): false

翻譯自: https://www.includehelp.com/java/observable-setchanged-method-with-example.aspx

observable

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