WinForm传递对象编辑后，主窗体如何同步更新属性值？

问题描述 #

我开发了一个简单的Pokemon WinForm应用，包含两个窗体：Form1用于展示Pokemon及其关联属性；点击编辑按钮后，会弹出EditCharacter窗体（Form2），允许用户编辑角色属性。我从Form1传入currentCharacter对象让EditCharacter加载选中的Pokemon，但修改属性后返回Form1，数值并未更新（比如把Rayquaza的HealthPoints改成0，Form1里还是原来的数值）。

现有代码 #

Form1代码 #

public partial class Form1 : Form
{
    CardCollection cardCollection;
    public Character currentCharacter;
  
    public Form1()
    {
        InitializeComponent();
        cardCollection = new CardCollection();  
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        foreach (var keyValuePair in cardCollection.Cards)
        {
            cmbPokemon.Items.Add(keyValuePair.Key);
        }
    }

    private void cmbPokemon_SelectedIndexChanged(object sender, EventArgs e)
    {
        currentCharacter = cardCollection.Cards[cmbPokemon.Text];
        updateControls();
    }

    public void updateControls()
    {
        lblHP.Text = currentCharacter.HealthPoints.ToString();
        lblStrength.Text = currentCharacter.Strength.ToString();
        lblSpecialPower.Text = currentCharacter.SpecialPower;
        pbPokemon.ImageLocation = @currentCharacter.FileName;
    }

    private void btnEdit_Click(object sender, EventArgs e)
    {
        EditCharacter EditChar = new EditCharacter(currentCharacter);
        EditChar.ShowDialog();
    }       
}

EditCharacter窗体代码 #

public partial class EditCharacter : Form
{
    Character currentCharacter;
    public EditCharacter( Character c)
    {
        InitializeComponent();
        currentCharacter  = new Character();
        currentCharacter = c;
        lblCharacter.Text = c.Name;
        pbCharacter.ImageLocation = c.FileName;
        txtPower.Text = c.SpecialPower;
        tbHP.Value = c.HealthPoints;
        tbStrength.Value = c.Strength;
        lblHP.Text = c.HealthPoints.ToString();
        lblStrength.Text = c.Strength.ToString();
    }

    private void trackBar1_Scroll(object sender, EventArgs e)
    {
        lblHP.Text = tbHP.Value.ToString();
    }

    private void tbPower_Scroll(object sender, EventArgs e)
    {
        lblStrength.Text = tbStrength.Value.ToString();
    }

    private void btnSave_Click(object sender, EventArgs e)
    {
        currentCharacter.Name = lblCharacter.Text;
        currentCharacter.FileName = pbCharacter.ImageLocation;
        currentCharacter.SpecialPower = txtPower.Text;
        currentCharacter.HealthPoints = tbHP.Value;
        currentCharacter.Strength = tbStrength.Value;
        currentCharacter.SpecialPower = txtPower.Text;
        this.Close();
    }
}

解决方案 #

核心原因 #

Character是引用类型，你在EditCharacter中修改的属性其实已经同步到Form1的currentCharacter对象里了，但Form1的控件没有重新读取这些更新后的属性值，所以看不到变化。另外EditCharacter构造函数里的currentCharacter = new Character();是多余代码，不影响功能但可以删掉。

修改步骤 #

1. 更新Form1的编辑按钮事件：在关闭EditCharacter对话框后，立即调用updateControls()刷新控件显示

private void btnEdit_Click(object sender, EventArgs e)
{
    EditCharacter EditChar = new EditCharacter(currentCharacter);
    EditChar.ShowDialog();
    // 对话框关闭后刷新Form1的控件
    updateControls();
}

2. 优化EditCharacter构造函数：删除多余的对象初始化代码，简化为：

public EditCharacter(Character c)
{
    InitializeComponent();
    currentCharacter = c;
    lblCharacter.Text = c.Name;
    pbCharacter.ImageLocation = c.FileName;
    txtPower.Text = c.SpecialPower;
    tbHP.Value = c.HealthPoints;
    tbStrength.Value = c.Strength;
    lblHP.Text = c.HealthPoints.ToString();
    lblStrength.Text = c.Strength.ToString();
}

这样修改后，编辑完属性关闭EditCharacter窗体，Form1的控件就会自动刷新显示最新的属性值了。

内容的提问来源于stack exchange，提问作者Tiny