环境：现在有两个窗体，一个父窗体，一个子窗体，如下图示。
目的：子窗体显示出来以后，点击父窗体的修改按钮可以修改子窗体的标题，点击子窗体的修改按钮可以修改父窗体的标题。
1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Windows.Forms; 9 10 namespace 窗体传值 11 { 12 public partial class MainForm : Form 13 { 14 public MainForm() 15 { 16 InitializeComponent(); 17 isEnabled(true); 18 } 19 Form sf; 20 private void btnSubShow_Click(object sender, EventArgs e) 21 { 22 sf = new SubForm(this); 23 sf.Show(); 24 isEnabled(false); 25 } 26 private void btnSubClose_Click(object sender, EventArgs e) 27 { 28 sf.Close(); 29 isEnabled(true); 30 } 31 private void btnSubChange_Click(object sender, EventArgs e) 32 { 33 sf.Text = txtSubTitle.Text.Trim(); 34 } 35 public void isEnabled(bool isEnabled) 36 { 37 btnSubChange.Enabled = !isEnabled; 38 btnSubClose.Enabled = !isEnabled; 39 btnSubShow.Enabled = isEnabled; 40 } 41 } 42 }
1 namespace 窗体传值 2 { 3 partial class MainForm 4 { 5 /// <summary> 6 /// 必需的设计器变量。 7 /// </summary> 8 private System.ComponentModel.IContainer components = null; 9 10 /// <summary> 11 /// 清理所有正在使用的资源。 12 /// </summary> 13 /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param> 14 protected override void Dispose(bool disposing) 15 { 16 if (disposing && (components != null)) 17 { 18 components.Dispose(); 19 } 20 base.Dispose(disposing); 21 } 22 23 #region Windows 窗体设计器生成的代码 24 25 /// <summary> 26 /// 设计器支持所需的方法 - 不要 27 /// 使用代码编辑器修改此方法的内容。 28 /// </summary> 29 private void InitializeComponent() 30 { 31 this.btnSubShow = new System.Windows.Forms.Button(); 32 this.btnSubClose = new System.Windows.Forms.Button(); 33 this.btnSubChange = new System.Windows.Forms.Button(); 34 this.txtSubTitle = new System.Windows.Forms.TextBox(); 35 this.lbSubTitle = new System.Windows.Forms.Label(); 36 this.SuspendLayout(); 37 // 38 // btnSubShow 39 // 40 this.btnSubShow.Location = new System.Drawing.Point(39, 30); 41 this.btnSubShow.Name = "btnSubShow"; 42 this.btnSubShow.Size = new System.Drawing.Size(75, 23); 43 this.btnSubShow.TabIndex = 0; 44 this.btnSubShow.Text = "显示子窗体"; 45 this.btnSubShow.UseVisualStyleBackColor = true; 46 this.btnSubShow.Click += new System.EventHandler(this.btnSubShow_Click); 47 // 48 // btnSubClose 49 // 50 this.btnSubClose.Location = new System.Drawing.Point(39, 79); 51 this.btnSubClose.Name = "btnSubClose"; 52 this.btnSubClose.Size = new System.Drawing.Size(75, 23); 53 this.btnSubClose.TabIndex = 1; 54 this.btnSubClose.Text = "关闭子窗体"; 55 this.btnSubClose.UseVisualStyleBackColor = true; 56 this.btnSubClose.Click += new System.EventHandler(this.btnSubClose_Click); 57 // 58 // btnSubChange 59 // 60 this.btnSubChange.Location = new System.Drawing.Point(205, 79); 61 this.btnSubChange.Name = "btnSubChange"; 62 this.btnSubChange.Size = new System.Drawing.Size(75, 23); 63 this.btnSubChange.TabIndex = 2; 64 this.btnSubChange.Text = "修改"; 65 this.btnSubChange.UseVisualStyleBackColor = true; 66 this.btnSubChange.Click += new System.EventHandler(this.btnSubChange_Click); 67 // 68 // txtSubTitle 69 // 70 this.txtSubTitle.Location = new System.Drawing.Point(211, 33); 71 this.txtSubTitle.Name = "txtSubTitle"; 72 this.txtSubTitle.Size = new System.Drawing.Size(100, 21); 73 this.txtSubTitle.TabIndex = 3; 74 // 75 // lbSubTitle 76 // 77 this.lbSubTitle.AutoSize = true; 78 this.lbSubTitle.Location = new System.Drawing.Point(131, 38); 79 this.lbSubTitle.Name = "lbSubTitle"; 80 this.lbSubTitle.Size = new System.Drawing.Size(77, 12); 81 this.lbSubTitle.TabIndex = 4; 82 this.lbSubTitle.Text = "子窗体标题："; 83 // 84 // MainForm 85 // 86 this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F); 87 this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; 88 this.ClientSize = new System.Drawing.Size(363, 150); 89 this.Controls.Add(this.lbSubTitle); 90 this.Controls.Add(this.txtSubTitle); 91 this.Controls.Add(this.btnSubChange); 92 this.Controls.Add(this.btnSubClose); 93 this.Controls.Add(this.btnSubShow); 94 this.Name = "MainForm"; 95 this.Text = "MainForm"; 96 this.ResumeLayout(false); 97 this.PerformLayout(); 98 99 } 100 101 #endregion 102 103 private System.Windows.Forms.Button btnSubShow; 104 private System.Windows.Forms.Button btnSubClose; 105 private System.Windows.Forms.Button btnSubChange; 106 private System.Windows.Forms.TextBox txtSubTitle; 107 private System.Windows.Forms.Label lbSubTitle; 108 } 109 }
1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Windows.Forms; 9 10 namespace 窗体传值 11 { 12 public partial class SubForm : Form 13 { 14 Form mainForm; 15 public SubForm() 16 { 17 InitializeComponent(); 18 } 19 public SubForm(Form m):this() 20 { 21 this.mainForm = m; 22 } 23 private void btnMainChange_Click(object sender, EventArgs e) 24 { 25 mainForm.Text = txtMainTitle.Text.Trim(); 26 } 27 } 28 }
1 namespace 窗体传值 2 { 3 partial class SubForm 4 { 5 /// <summary> 6 /// Required designer variable. 7 /// </summary> 8 private System.ComponentModel.IContainer components = null; 9 10 /// <summary> 11 /// Clean up any resources being used. 12 /// </summary> 13 /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> 14 protected override void Dispose(bool disposing) 15 { 16 if (disposing && (components != null)) 17 { 18 components.Dispose(); 19 } 20 base.Dispose(disposing); 21 } 22 23 #region Windows Form Designer generated code 24 25 /// <summary> 26 /// Required method for Designer support - do not modify 27 /// the contents of this method with the code editor. 28 /// </summary> 29 private void InitializeComponent() 30 { 31 this.lbMainTitle = new System.Windows.Forms.Label(); 32 this.txtMainTitle = new System.Windows.Forms.TextBox(); 33 this.btnMainChange = new System.Windows.Forms.Button(); 34 this.SuspendLayout(); 35 // 36 // lbMainTitle 37 // 38 this.lbMainTitle.AutoSize = true; 39 this.lbMainTitle.Location = new System.Drawing.Point(65, 47); 40 this.lbMainTitle.Name = "lbMainTitle"; 41 this.lbMainTitle.Size = new System.Drawing.Size(77, 12); 42 this.lbMainTitle.TabIndex = 9; 43 this.lbMainTitle.Text = "主窗体标题："; 44 // 45 // txtMainTitle 46 // 47 this.txtMainTitle.Location = new System.Drawing.Point(145, 42); 48 this.txtMainTitle.Name = "txtMainTitle"; 49 this.txtMainTitle.Size = new System.Drawing.Size(152, 21); 50 this.txtMainTitle.TabIndex = 8; 51 // 52 // btnMainChange 53 // 54 this.btnMainChange.Location = new System.Drawing.Point(144, 89); 55 this.btnMainChange.Name = "btnMainChange"; 56 this.btnMainChange.Size = new System.Drawing.Size(75, 23); 57 this.btnMainChange.TabIndex = 7; 58 this.btnMainChange.Text = "修改"; 59 this.btnMainChange.UseVisualStyleBackColor = true; 60 this.btnMainChange.Click += new System.EventHandler(this.btnMainChange_Click); 61 // 62 // SubForm 63 // 64 this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F); 65 this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; 66 this.ClientSize = new System.Drawing.Size(363, 150); 67 this.Controls.Add(this.lbMainTitle); 68 this.Controls.Add(this.txtMainTitle); 69 this.Controls.Add(this.btnMainChange); 70 this.Name = "SubForm"; 71 this.Text = "SubForm"; 72 this.ResumeLayout(false); 73 this.PerformLayout(); 74 75 } 76 77 #endregion 78 79 private System.Windows.Forms.Label lbMainTitle; 80 private System.Windows.Forms.TextBox txtMainTitle; 81 private System.Windows.Forms.Button btnMainChange; 82 } 83 }
主窗口想要修改子窗口标题很简单，因为在主窗体中中已经创建了一个子窗体的对象sf，并且已经实例化
1 Form sf; 2 private void btnSubShow_Click(object sender, EventArgs e) 3 { 4 sf = new SubForm(this); 5 sf.Show(); 6 isEnabled(false); 7 }
点击按钮后将txtSubTitle.Text.Trim()直接传给子窗体的Text属性，也就是sf.Text
1 private void btnSubChange_Click(object sender, EventArgs e) 2 { 3 sf.Text = txtSubTitle.Text.Trim(); 4 }
但是，子窗体怎么修改主窗体的标题呢？主窗体为什么能修改子窗体的标题，因为在主窗体中已经定义了子窗体的引用，所以可以通过引用直接将标题传给子窗体。子窗体想要修改主窗体的标题，也必须获得父窗体的引用。
不管是父窗体，还是子窗体，都是以类的形式存在的，类和类之间的传值，就要用到构造方法，在将子窗体实例化的时候，将主窗体的引用通过构造方法传进去。首先要在子窗体中定义一个构造方法。构造方法中有一个参数为主窗体的类型Form，用来接收传进去的主窗体。
1 public SubForm(Form m):this() 2 { 3 this.mainForm = m; 4 }
子窗体可以接收了，父窗体怎么传呢？就是在实例化子窗体引用的时候，通过构造方法，将自己传进去。
1 private void btnSubShow_Click(object sender, EventArgs e) 2 { 3 sf = new SubForm(this); 4 sf.Show(); 5 isEnabled(false); 6 }
这里的sf=new SubForm(this);就是将自己this，做为参数传进构造方法中。这时子窗体中就有了父窗体的引用mainForm，就可以更改父窗体的属性了。
1 private void btnMainChange_Click(object sender, EventArgs e) 2 { 3 mainForm.Text = txtMainTitle.Text.Trim(); 4 }
疑问：这个问题解决了，但是，这个程序存在一个问题，子窗体点击关闭按钮，就是那个红色的X后，子窗体关闭了，但是父窗体的“关闭子窗体”和“修改”按钮，依然可以点击，也就是没有执行父窗口中的isEnabled()方法，具体应该怎么才能执行到，目前我还解决不了，等有时间的时候，我会解决它的！