无法在 JPanel 引用上调用"this.firePropertyChange()"

Question

为什么不能在this引用上调用firePropertyChange() ?

    [javac] /home/thufir/NetBeansProjects/Legacy/src/legacy/gui/table/SelectTableFollowup.java:41: error: cannot find symbol
    [javac]                     this.firePropertyChange("client", null, i);
    [javac]                         ^
    [javac]   symbol: method firePropertyChange(String,<null>,int)
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 1 error
    [javac] 1 warning
BUILD FAILED
/home/thufir/NetBeansProjects/Legacy/nbproject/build-impl.xml:923: The following error occurred while executing this line:
/home/thufir/NetBeansProjects/Legacy/nbproject/build-impl.xml:263: Compile failed; see the compiler error output for details.
Total time: 4 seconds
thufir@dur:~/NetBeansProjects/Legacy$ 

这是我的代码:

package legacy.gui.table;
import java.awt.BorderLayout;
import java.util.logging.Logger;
import javax.swing.JPanel;
import legacy.database.Queries;
public class SelectTableFollowup extends JPanel {
    private static final Logger log = Logger.getLogger(SelectTableFollowup.class.getName());
    private ClientsTable table;
    private Followup followup;
    private Select Select;
    private final Queries queries = new Queries();
    public SelectTableFollowup() {
        initComponents();
    }
    private void initComponents() {
        table = new ClientsTable();
        followup = new Followup();
        Select = new Select();
        setLayout(new BorderLayout());
        add(Select, BorderLayout.NORTH);
        add(table, BorderLayout.CENTER);
        add(followup, BorderLayout.SOUTH);
        followupButton();
        query();
        cannotFirePropertyChangeOnThisObj();
    }
    private void cannotFirePropertyChangeOnThisObj() {
        table.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
            @Override
            public void propertyChange(java.beans.PropertyChangeEvent evt) {
                if ("client".equals(evt.getPropertyName())) {
                    String s = evt.getNewValue().toString();
                    int i = Integer.parseInt(s);
                    log.info("i is " + i);
                    this.firePropertyChange("client", null, i);
                }
            }
        });
    }
    private void followupButton() {
        followup.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
            @Override
            public void propertyChange(java.beans.PropertyChangeEvent evt) {
                if ("followup".equals(evt.getPropertyName())) {
                    try {
                        int id = table.getId();
                        queries.send(id);
                        table.updateModel();
                    } catch (ArrayIndexOutOfBoundsException obe) {
                        log.info(obe.toString());  //no big deal
                    }
                }
            }
        });
    }
    private void query() {
        Select.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
            @Override
            public void propertyChange(java.beans.PropertyChangeEvent evt) {
                if ("select".equals(evt.getPropertyName())) {
                    log.info(evt.getNewValue().toString());
                    table.select(evt.getNewValue().toString());
                }
            }
        });
    }
}

从Netbeans，我知道这是很可能调用this.firePropertyChange(), JPanel的Netbeans创建。

上面的类与Netbeans生成的类有什么不同?它们都扩展了同一个基类。

如果我误用了什么术语，请告诉我。

Answer 1

在此上下文中:

table.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
    @Override
    public void propertyChange(java.beans.PropertyChangeEvent evt) {
        ...
        this.firePropertyChange("client", null, i);
    }
}

关键字this是指创建新的PropertyChangeListener实例时生成的匿名内部类。这里解释了这个事实:使用This关键字

看一下这个主题:关键字为外部类从一个匿名的内部类?您应该将这一行替换为引用面板类的这一行:

table.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
    @Override
    public void propertyChange(java.beans.PropertyChangeEvent evt) {
        ...
        SelectTableFollowup.this.firePropertyChange("client", null, i);
    }
}

或者你可以删除this，编译器会为你解决同样的问题:

table.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
    @Override
    public void propertyChange(java.beans.PropertyChangeEvent evt) {
        ...
        firePropertyChange("client", null, i);
    }
}

如果匿名内部类没有任何firePropertyChange()方法，编译器将查找外部类(或最终的层次树)并检查它是否有这样的方法，情况确实如此。

Answer 2

我认为错误发生在这个方法:

private void cannotFirePropertyChangeOnThisObj() {
    table.addPropertyChangeListener(new java.beans.PropertyChangeListener() 
        @Override
        public void propertyChange(java.beans.PropertyChangeEvent evt) {
            if ("client".equals(evt.getPropertyName())) {
                String s = evt.getNewValue().toString();
                int i = Integer.parseInt(s);
                log.info("i is " + i);
                this.firePropertyChange("client", null, i);
            }
        }
    });
}

您正在匿名PropertyChangeListener对象上调用firePropertyChange()。文档声明它没有声明firePropertyChange()方法。

我认为你想在你的SelectTableFollowup对象上调用它。那么你必须像这样调用它:

private void cannotFirePropertyChangeOnThisObj() {
    table.addPropertyChangeListener(new java.beans.PropertyChangeListener() 
        @Override
        public void propertyChange(java.beans.PropertyChangeEvent evt) {
            if ("client".equals(evt.getPropertyName())) {
                String s = evt.getNewValue().toString();
                int i = Integer.parseInt(s);
                log.info("i is " + i);
                SelectTableFollowup.this.firePropertyChange("client", null, i); // Reference this of the outer class
            }
        }
    });
}

因为PropertyChangeListener没有声明这个方法，你也可以直接写firePropertyChange("client", null, i);