是否可以从初始化的 class 外部更改对象实例？

Question

我可能以错误的方式处理这件事。请赐教。提前致谢！！！

void initialize() {
more code...
JEditorPane textPane = new JEditorPane();
textPane.setEditable(false);
textPane.setBackground(Color.LIGHT_GRAY);
textPane.setText(" THE MESSAGE I WANT TO CHANGE FROM OUTSIDE initialize()");
more code....

public static void SomePrintClass(){
JEditorPane textPane = new JEditorPane();
textPane.setText("SOME NEW TEXT );        // I am aware this doesn't work 
//but is there a way it can be made to work???
more code.....

Answer 1

这是一个简单的例子，基本上你通过构造函数将一个 class 的实例传递给另一个。也可以通过其他方式完成...

public class Whosebug_33061019 {

    public class ExampleClass
    {
        String displayText;

        public ExampleClass()
        {
        }

        public String getDisplayText()
        {
            return displayText;
        }

        public void setDisplayText(String text)
        {
            this.displayText = text;
        }
    }

    public class AnotherClass
    {
        ExampleClass updateMe;

        public AnotherClass(ExampleClass example)
        {
            updateMe = example;
        }

        public void changeText()
        {
            updateMe.setDisplayText("Updated text from AnotherClass");
        }
    }

    public static void main(String[] args) 
    {
        Whosebug_33061019 ap=new Whosebug_33061019();
        ap.runIt();
    }

    public void runIt()
    {
        ExampleClass example = new ExampleClass();
        example.setDisplayText("Initial text");
        System.out.println("ExampleClass displayText: " + example.getDisplayText());

        AnotherClass another = new AnotherClass(example);
        another.changeText();
        System.out.println("ExampleClass displayText: " + example.getDisplayText());
    }

}

Answer 2

我猜想您只想更改 JEditorPane 的文本，而不是其他 class。如果是这样，那就很简单了。 Make the JEditorPane static 并使用 class 的名称调用其 setText() 方法。例如。

第一个Class.

public class First extends JFrame {

    static JEditorPane ep;
    First() {
        ep = new JEditorPane();
        setSize(new Dimension(200, 200));
        ep.setText("I expect to receive some text.");
        add(ep);
        setVisible(true);
    }

    @Override
    public void paintComponents(Graphics g) {
        super.paintComponents(g);
    }
}

第二个Class.

public class Second extends JFrame {

    JButton btn;
    JTextField jtf = new JTextField(16);
    JEditorPane ep;

    Second() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        btn = new JButton("Send above Text.");
        setSize(new Dimension(200, 200));
        btn.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
               ep = First.ep;
               ep.setText(jtf.getText());
               ep.setForeground(Color.red);
            }

        });
        this.setLayout(new FlowLayout());
        add(jtf);
        add(btn);
        setVisible(true);
    }

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            First so;

            @Override
            public void run() {
                new Second();
                so = new First();
            }
        });
    }
}

是否可以从初始化的 class 外部更改对象实例？

is it possible to change an object instance from outside the class it was initialized in?

java

swing

class

instance