从动态类引用动态设置器 [英] Referencing a dynamic setter from a dynamic class

问题描述

我试图引用一个安装程序...我收到帮助，并在解决问题之前选择了答案....看到这里：

所以，我在做的是一个简单的方法，它使用一个setter-from-outside-a-

  
 public class Log {
 private MainForm mainForm; // MainForm变量
 
 public Log（MainForm mainForm）{
 //将MainForm变量设置为其构造函数中的正确引用
 this.mainForm = mainForm; 
} 
 
 private void consoleOut（String data）{
 System.out.println（data）; 
 if（mainForm！= null）{
 //现在我们可以使用传入的引用
 mainForm.setConsoleText（data）; 
} 
} 
} 
  

。

  public class MainForm extends FrameView {
 public MainForm（SingleFrameApplication app）{
 super ; 
 ........... CUT FOR LENGTH ................. 
 public void setConsoleText（String Text）{
 jTextArea2.append（Text）; 
} 
  

b

由于某种原因，MainForm在Log类中总是出现null。

如何获得对我的主窗体的引用？

Meh ...我只是使用一个静态文本框和一个静态设置器....仍在寻找一个更好的主意。

解决方案

唯一的解释是，当你实例化Log时，你传递一个null到构造函数。您是否在分配之前调用新的日志（mainform）

  //不这样做
 private Log log = new Log（mainForm）; 
 
 private MainForm mainForm = new MainForm（）; 
  

检查您的对象的构造顺序。

I am trying to reference a setter... I received help and selected the answer too soon before resolving the issue.... see here: Using a setter from outside a form?

So, what I'm doing is this... Data goes into the log and it gets parsed, then it goes back to the form where it is displayed.

public class Log {
   private MainForm mainForm; // our MainForm variable

   public Log(MainForm mainForm) {
      // setting the MainForm variable to the correct reference in its constructor
      this.mainForm = mainForm;  
   }

   private  void consoleOut(String data) {
     System.out.println(data);
     if (mainForm != null) {
        // now we can use the reference passed in.
        mainForm.setConsoleText("data");
     }
   }
}

Here's the setter in my form.

public class MainForm extends FrameView {
    public MainForm(SingleFrameApplication app) {
        super(app);
...........CUT FOR LENGTH.................
    public void setConsoleText(String Text){
        jTextArea2.append(Text);
    }

edited for simplicity sake.

For some reason MainForm always comes out null in the Log class.

How can I get a reference to my Main form?

Meh... I just went with a static textbox and a static setter.... Still looking for a better idea.

解决方案

The only explanation is that when you are instantiating Log you are passing a null to the constructor. Are you calling new Log(mainform) before mainform has been assigned?

// Don't do this
private Log log = new Log(mainForm);

private MainForm mainForm = new MainForm();

Check the order of construction of your objects.

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