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我在传递 jtree 节点的值时遇到问题。我将节点值转换为字符串，然后将字符串传递给另一个从数据库返回字符串以显示在文本窗格中的方法，但这是错误的，输出消息是“java.lang.nullpointerexception”有人能帮帮我吗？
这是我的代码

    public class Selector implements TreeSelectionListener {

@Override
public void valueChanged(TreeSelectionEvent event) {
    // TODO Auto-generated method stub
     Object obj = event.getNewLeadSelectionPath().getLastPathComponent();
     String node = obj.toString();

     try{
     resultt = treelistener.SelectionListener(node);


     txtpane.setText(resultt);
     }
     catch (NullPointerException ne){
         System.out.print(ne);
     }
}
}

这是treelistener代码

            public class TreeListener {

DbConnection connection;
Statement st = null;
ResultSet rs = null;
String result = null;


public String SelectionListener(String node) {
    // TODO Auto-generated method stub
    Connection con = connection.openConnection();
    System.out.print(node);

    String sql = "Select penjelasan from tArtikel where judul = '%" + node +"%'"  ;
    try{


        st = con.createStatement();
        rs = st.executeQuery(sql);
            while (rs.next()) {
                result = rs.getString(1);
                }
        rs.close();
        st.close();
        con.close();
        System.out.print(result);
    }
    catch (Exception e){
        System.out.println(e);
    }

    return result;
}




    }

谢谢你

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1 回答 1

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have you initialize your object from class TreeListener? Please create a code like this in your valueChanged object :

TreeListener treelistener=new TreeListener();

Please tell us again what is like after you add that code.

于 2013-04-17T03:29:46.757 回答