ImageView onClickListener（）不起作用

Question

ImageView onclicklistener不适用于以下代码。它在nullPointerException中显示setOnClickListener。

    ImageView cus_image = (ImageView) findViewById(R.drawable.cust_list);
    cus_image.setOnClickListener(new View.OnClickListener() 
        {
        public void onClick(final View v) 
          {
             Intent myIntent = new Intent(v.getContext(), Customer.class);
              startActivity(myIntent); 
        } 

    });

错误日志。

                    10-16 13:15:40.167: E/AndroidRuntime(568): FATAL EXCEPTION: main
                    10-16 13:15:40.167: E/AndroidRuntime(568): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.First.namespace/com.tiara.tallyApp.New_grid_activity}: java.lang.NullPointerException
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.os.Handler.dispatchMessage(Handler.java:99)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.os.Looper.loop(Looper.java:123)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread.main(ActivityThread.java:4627)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at java.lang.reflect.Method.invokeNative(Native Method)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at java.lang.reflect.Method.invoke(Method.java:521)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at dalvik.system.NativeStart.main(Native Method)
                    10-16 13:15:40.167: E/AndroidRuntime(568): Caused by: java.lang.NullPointerException
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at com.tiara.tallyApp.New_grid_activity.onCreate(New_grid_activity.java:24)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
                    10-16 13:15:40.167: E/AndroidRuntime(568):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

请帮助我解决问题。

Answer 1

这应该解决问题

ImageView cus_image = (ImageView) findViewById(R.id.cust_list);
cus_image.setOnClickListener(new View.OnClickListener() 
{
public void onClick(final View v) 
  {
     Intent myIntent = new Intent(v.getContext(), Customer.class);
      startActivity(myIntent); 
  } 
});

用R.id更改R.drawable

Answer 2

替换

ImageView cus_image = (ImageView) findViewById(R.drawable.cust_list);

与

ImageView cus_image = (ImageView) findViewById(R.id.cust_list_img_id); // cust_list_img_id will be id of that imageview in xml file.

Answer 3

失败的是：

ImageView cus_image = (ImageView) findViewById(R.drawable.cust_list);

仅通过查看名称“ cust_list”和一个“ drawable”而不是“ id”？

Answer 4

您正在尝试从drawable获取imageview的引用，除了应该将imageview id作为R.id.yourimageviewId。

尝试如下：

  ImageView cus_image = (ImageView) findViewById(R.id.<youriamgeid>);

Answer 5

像这样使用

ImageView cus_image = (ImageView) findViewById(R.id.cust_list);
cus_image.setOnClickListener(new View.OnClickListener() 
    {
    public void onClick(final View v) 
      {
         Intent myIntent = new Intent(getContext(), Customer.class);
          startActivity(myIntent); 
    } 

});

Answer 6

当然，请更改您获取图像的方式：

ImageView cus_image = (ImageView) findViewById(R.id.cust_list_img_id);

您必须使用在布局中设置的ID而不是要显示的可绘制对象来引用它。

Answer 7

您在：遇到错误：

ImageView cus_image = (ImageView) findViewById(**R.drawable.cust_list**);

用以下内容替换：

ImageView cus_image = (ImageView) findViewById(**R.id.imageid**);

Answer 8

它显示空指针异常，因为Imageview没得到您定义的idImageView cus_image =（ImageView）findViewById（R.drawable.cust_list）;

应为：ImageView cus_image =（ImageView）findViewById（R.id.cust_list）;