java - 如何获取当前显示的图像位置？

Question

我想在病房前后显示图像。像 Windows 图片和传真查看器这是我的代码:

  package com.my.imagechange;

  import android.app.Activity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.Button;
  import android.widget.ImageButton;
  import android.widget.ImageView;

  public class ImageChangeDemo extends Activity 
  {
/** Called when the activity is first created. */

 //  private Gallery gallery;
 private ImageView imgView;
 int i=0;
 int j=6;
ImageButton btrt,btlt;
Button bt1,bt2;
 private Integer[] Imgid ={R.drawable.androidlogo,R.drawable.androids, R.drawable.cool, R.drawable.cupcake2009, R.drawable.donut2009, R.drawable.eclair2009};
 int imglength=Imgid.length;
 //System.out.println(imglength);
 @Override

public void onCreate(Bundle savedInstanceState)
{

    super.onCreate(savedInstanceState);

      setContentView(R.layout.imagechange);
      System.out.println(imglength);

      btlt=(ImageButton)findViewById(R.id.bt1);
      btrt=(ImageButton)findViewById(R.id.bt2);


         imgView = (ImageView)findViewById(R.id.ImageView01);
  imgView.setImageResource(Imgid[0]);
    btlt.setOnClickListener(new View.OnClickListener()
         {

            @Override
            public void onClick(View v)
            {

                int choice1=j--;
                switch(choice1)
                {
                case 5:imgView.setImageResource(Imgid[5]);
                        break;
                case 4:imgView.setImageResource(Imgid[4]);
                        break;
                case 3:imgView.setImageResource(Imgid[3]);
                        break;
                case 2:imgView.setImageResource(Imgid[2]);
                        break;
                case 1:imgView.setImageResource(Imgid[1]);
                        break;

                }

            }
        });
         btrt.setOnClickListener(new View.OnClickListener() 
         {  @SuppressWarnings("unused")
        @Override


             public void onClick(View v) 
            {
                 int choice2=i++;
             switch(choice2)
             {
             case 1:imgView.setImageResource(Imgid[1]);
                    break;
             case 2:imgView.setImageResource(Imgid[2]);
                    break;
             case 3:imgView.setImageResource(Imgid[3]);
                    break;
             case 4:imgView.setImageResource(Imgid[4]);
                    break;
             case 5:imgView.setImageResource(Imgid[5]);
                    break;
             }
            }   

    });

}}            

它向前运行正常，但是当我向后单击时它不起作用。我在哪里犯了错误？谁能告诉我？

提前致谢。

Answer 1

请这样改

int choice1=--j;

编辑:这里的问题是在执行此代码后 int choice1=j--; choice1 包含值 6，这不在 switch case 中