observable

可观察的类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()方法用于将此Observable对象状态设置为已更改。

• 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()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

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

  setChanged()方法在设置更改状态时不会引发异常。

Syntax:

句法：

    protected void setChanged();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

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

该方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example
// of void setChanged() method of Observable
import 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 Method
public static void main(String args[]) {Observed observed = new Observed();
Observers obs = new Observers();
observed.addObserver(obs);
observed.setChange();
observed.unsetChange();
}
}

Output

输出量

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

翻译自: https://www.includehelp.com/java/observable-setchanged-method-with-example.aspx

observable