在我的程序中,我正在使用一个带有一些图像的网格视图,我想在用户点击网格视图中的图像时显示一个菜单,然后从显示的菜单中选择要执行的操作。
下面是我的代码:
package Kazemi.Alireza.scada;
import android.annotation.SuppressLint;
import android.app.Dialog;
import android.app.FragmentManager;
import android.content.Context;
import android.graphics.Typeface;
import android.graphics.drawable.AnimationDrawable;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.PopupWindow;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
@SuppressLint("NewApi")
public class CitiesTab extends Fragment {
AnimationDrawable[] frameAnimation;
ImageAdapter ia;
GridView gridView;
int in;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return (LinearLayout)inflater.inflate(R.layout.citytab, container, false);
}
public void onStart()
{
super.onStart();
ia = new ImageAdapter(getActivity());
gridView = (GridView) getActivity().findViewById(R.id.gridview);
gridView.setAdapter(ia);
gridView.post(new Starter());
gridView.setOnItemClickListener(new OnItemClickListener()
{
public void onItemClick(AdapterView<?> parent, View v, int position, long id)
{
dialog = new Dialog(getActivity(), android.R.style.Theme_InputMethod);
dialog.setContentView(R.layout.pump_menu);
}});
/*Button btn = (Button) getActivity().findViewById(R.id.Button_pumpInfo);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getActivity(), "You clicked on Item 1",
Toast.LENGTH_LONG).show();
}
});*/
}
public void Btn_pumpInfo_Clicked(View v) {
// TODO Auto-generated method stub
Toast.makeText(getActivity(), "You clicked on Item 1",
Toast.LENGTH_LONG).show();
}
}
下面是我的pump_menu.xml代码:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#a5c5f0"
android:orientation="vertical" >
<Button
android:id="@+id/Button_pumpInfo"
android:layout_height="40dp"
android:text="@string/menu_pumpinfo_item1"
android:textSize="11sp"
android:layout_width="125dp"
android:background="#a5c5f0"
android:onClick="Btn_pumpInfo_Clicked"/>
和citytab.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<GridView
android:id="@+id/gridview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:numColumns="auto_fit"
android:verticalSpacing="10dp"
android:horizontalSpacing="10dp"
android:columnWidth="90dp"
android:stretchMode="columnWidth"
android:gravity="center" />
<ImageView
android:id="@+id/gifViewer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="center"/>
</LinearLayout>
当我使用这段代码时,出现了一个错误:
java.lang.RuntimeException: Unable to start activity ComponentInfo{Kazemi.Alireza.scada/Kazemi.Alireza.scada.MainMenu}: java.lang.NullPointerException
当我注释Btn_pumpInfo_Clicked()方法,并在onStart()中取消注释按钮侦听器时,发生了以下错误:
java.lang.IllegalStateException: Could not find a method Btn_pumpInfo_Clicked(View) in the activity class android.view.ContextThemeWrapper for onClick handler on view class android.widget.Button with id 'Button_pumpInfo'
问题出在哪里?谢谢
发布于 2012-12-06 17:28:57
你不能在Dialog
类中注册Button
的onClick
回调(使用android:onClick
),因为安卓不会找到它,因为它只会在 Activity
中搜索与该名称匹配的方法(Btn_pumpInfo_Clicked
),并会抛出异常。取而代之的是在Dialog
中查找Button
并为其分配一个普通的侦听器:
//...
dialog.setContentView(R.layout.pump_menu)
Button b = (Button) dialog.findViewById(R.id.Button_pumpInfo);
b.setOnClickListener(new OnClickListener() {
@Override
public void onCLick(View v) {
// profit
}
});
或者移动该方法:
public void Btn_pumpInfo_Clicked(View v) {
// TODO Auto-generated method stub
Toast.makeText(getActivity(), "You clicked on Item 1",
Toast.LENGTH_LONG).show();
}
在Activity
类中,如果适合您的话。
发布于 2013-10-03 20:51:15
如果这个错误只发生在Android2.x上,请检查您的Activity类层次结构中特定于Android4的类成员:
public class HomeActivity extends Activity {
private android.app.ActionBar.LayoutParams customTitleParams;
....
}
类android.app.ActionBar.LayoutParams
在Android2.x上不可用,这可能会导致问题。
发布于 2017-07-05 19:24:09
当调用视图(按钮)的onClick的方法不可访问或在相应的活动中不可用时,也会发生这种情况。检查步骤:
https://stackoverflow.com/questions/13739962
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