现在它给了我这种Logcat错误：
11-20 11:19:04.729: E/AndroidRuntime(447): FATAL EXCEPTION: main
11-20 11:19:04.729: E/AndroidRuntime(447): java.lang.NullPointerException
11-20 11:19:04.729: E/AndroidRuntime(447): at com.example.orderplacemnet.ImageAdapter.getView(OnlineShopping.java:157)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:192)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.View.measure(View.java:8171)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.LinearLayout.measureVertical(LinearLayout.java:381)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.View.measure(View.java:8171)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.View.measure(View.java:8171)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.LinearLayout.measureVertical(LinearLayout.java:526)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.View.measure(View.java:8171)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.View.measure(View.java:8171)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.ViewRoot.performTraversals(ViewRoot.java:801)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.os.Handler.dispatchMessage(Handler.java:99)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.os.Looper.loop(Looper.java:123)
11-20 11:19:04.729: E/AndroidRuntime(447): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-20 11:19:04.729: E/AndroidRuntime(447): at java.lang.reflect.Method.invokeNative(Native Method)
11-20 11:19:04.729: E/AndroidRuntime(447): at java.lang.reflect.Method.invoke(Method.java:521)
11-20 11:19:04.729: E/AndroidRuntime(447): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
11-20 11:19:04.729: E/AndroidRuntime(447): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
11-20 11:19:04.729: E/AndroidRuntime(447): at dalvik.system.NativeStart.main(Native Method)
此活动用于将图像适配器添加到库中但不起作用。 我正在研究android 2.0版本。
Logcat错误：
11-20 10:46:36.118: E/AndroidRuntime(420): FATAL EXCEPTION: main
11-20 10:46:36.118: E/AndroidRuntime(420): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.orderplacemnet/com.example.orderplacemnet.OnlineShopping}: java.lang.NullPointerException
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.os.Handler.dispatchMessage(Handler.java:99)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.os.Looper.loop(Looper.java:123)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-20 10:46:36.118: E/AndroidRuntime(420): at java.lang.reflect.Method.invokeNative(Native Method)
11-20 10:46:36.118: E/AndroidRuntime(420): at java.lang.reflect.Method.invoke(Method.java:521)
11-20 10:46:36.118: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
11-20 10:46:36.118: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
11-20 10:46:36.118: E/AndroidRuntime(420): at dalvik.system.NativeStart.main(Native Method)
11-20 10:46:36.118: E/AndroidRuntime(420): Caused by: java.lang.NullPointerException
11-20 10:46:36.118: E/AndroidRuntime(420): at com.example.orderplacemnet.OnlineShopping.onCreate(OnlineShopping.java:51)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-20 10:46:36.118: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
11-20 10:46:36.118: E/AndroidRuntime(420): ... 11 more
代码：
package com.example.orderplacemnet;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.SpinnerAdapter;
import android.widget.Toast;
import android.widget.ImageView;
public class OnlineShopping extends Activity {
Gallery myRoseGallery;
private List<Drawable> drawables=null;
// ImageView img;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_online_shopping);
myRoseGallery=(Gallery)findViewById(R.id.rosegallery);
//img=(ImageView)findViewById(R.id.roseimg);
Toast.makeText(this, "dfhgkhj", Toast.LENGTH_SHORT).show();
getDrawablesList();
myRoseGallery.setAdapter(new ImageAdapter(this));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// TODO Auto-generated method stub
return super.onCreateOptionsMenu(menu);
}
private void getDrawablesList() {
drawables = new ArrayList<Drawable>();
drawables.add(getResources().getDrawable(R.drawable.rose_five));
drawables.add(getResources().getDrawable(R.drawable.rose));
drawables.add(getResources().getDrawable(R.drawable.rose_two));
drawables.add(getResources().getDrawable(R.drawable.rose_three));
drawables.add(getResources().getDrawable(R.drawable.rose_four));
}
// private void setSelectedImage(int selectedImagePosition) {
//
// BitmapDrawable bd = (BitmapDrawable) drawables.get(selectedImagePosition);
// Bitmap b = Bitmap.createScaledBitmap(bd.getBitmap(), (int) (bd.getIntrinsicHeight() * 0.9), (int) (bd.getIntrinsicWidth() * 0.7), false);
//
//
// }
}
class ImageAdapter extends BaseAdapter{
private int[] myRoseImage = { R.drawable.rose, R.drawable.rose_two,
R.drawable.rose_three, R.drawable.rose_four,R.drawable.rose_five };
private Context myContext=null;
private Activity context=null;
private static ImageView iv=null;
private List<Drawable> plotsImages=null;
private static ViewHolder holder=null;
public ImageAdapter(Activity context, List<Drawable> plotsImages) {
this.context = context;
this.plotsImages = plotsImages;
}
public ImageAdapter(Context c) {
super();
// give yr conext here
this.myContext=c;
}
@Override
public int getCount() {
// how many image is there
return this.myRoseImage.length;
}
@Override
public Object getItem(int position) {
//which item is selected
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View view, ViewGroup parent) {
// display image in yr Image view as per yr view and position
if (view == null) {
holder = new ViewHolder();
ImageView iv = new ImageView(this.myContext);
iv.setPadding(3, 3, 3, 3);
view = iv;
holder.imageView = iv;
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}
holder.imageView.setImageDrawable(plotsImages.get(position));
holder.imageView.setScaleType(ImageView.ScaleType.FIT_XY);
holder.imageView.setLayoutParams(new Gallery.LayoutParams(150, 90));
return iv;
}
private static class ViewHolder {
ImageView imageView;
}
}
答案 0 :(得分：4)
如果您未使用findViewById() ...
setContentView()找到观看次数
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(R.layout.xxx); Add the layout that contains rosegallery
myRoseGallery=(Gallery)findViewById(R.id.rosegallery);
或者，如果图库是您想要的唯一视图，则可以使用：
myRoseGallery = new Gallery(this);
（了解Gallery类已弃用，将来不再支持。）
<强>加成
您应该从myRoseImage中的getItem()返回有效ID：
@Override
public int getItem(int position) {
//which item is selected
return myRoseImage[position];
}
并更新您在getView()中设置图片的方式：
holder.imageView.setImageResource(getItem(position));
您无法调用plotImages.get(position)，因为使用此构造函数时plotImages仍为null：
public ImageAdapter(Context c) {
super();
// give yr conext here
this.myContext=c;
}
答案 1 :(得分：3)
您的在线购物活动缺少setContentView();以设置包含布局。在super.onCreate（savedInstanceState）之后添加setContentView;在找到任何视图之前：
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.Your_layout_id); //add here
myRoseGallery=(Gallery)findViewById(R.id.rosegallery);
//img=(ImageView)findViewById(R.id.roseimg);
Toast.makeText(this, "dfhgkhj", Toast.LENGTH_SHORT).show();