从其他形式更改 Picturebox 的图像

Question

我想从另一个表单按钮更改图片框的图像。

我制作的程序没有显示错误，但在运行时，它显示错误“对象引用未设置为对象的实例”。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SCADA_training
{
    public partial class Form1 : Form
    {
       // private Form2 frm2;
        public Form1()
        {
            InitializeComponent();


        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {

        }



        private void button3_Click(object sender, EventArgs e)
        {
            Form2 A = new Form2();
            A.Show();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SCADA_training
{
    public partial class Form2 : Form
    {
        public Form1 frm1;
        public object pictureBox1 { get; private set; }

        public Form2()
        {
            InitializeComponent();

    }


        public void button2_Click(object sender, EventArgs e)
        {

           frm1.pictureBox1.Image = PROJECT.Properties.Resources._1;


        }

        public void button1_Click(object sender, EventArgs e)
        {


            frm1.pictureBox1.Image = PROJECT.Properties.Resources._2;


        }
    }
}

请帮帮我，我是初学者

Note：此问题总结整理于: Change Image of Picturebox from other form

Answer 1

尝试添加一行：

private void button3_Click(object sender, EventArgs e)
{
   Form2 A = new Form2();
   A.frm1 = this; // added line
   A.Show();
}

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