Java Android Studio 应用程序开发 - NullPointerException。我的应用程序强制在第二次加载时关闭 Activity
Java Android Studio Application Development - NullPointerException. My Application force closes when it loads second Activity
我的 Android 应用程序 (AA) 出现致命异常：main java.lang.NullPointerException。我的 AA 有两个活动，第一个屏幕是基本配置文件主屏幕，第二个是图片库。我还不是很擅长调试，所以我无法弄清楚为什么第二个 activity 强制关闭 (FC)。
你能给我指出正确的方向吗？
主要Activity
package com.gallery.brien.picturegallery;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Picture;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class Main extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void changePicture(View view) {
/* Open picture gallery activity */
Intent intent = new Intent(this,PictureGallery.class);
startActivity(intent);
}
}
第二个Activity
package com.gallery.brien.picturegallery;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;
public class PictureGallery extends Activity {
//variable array where pictures are store
Integer[] Profile = {R.drawable.brien, R.drawable.kick, R.drawable.mma, R.drawable.fun,
R.drawable.run};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.picture_gallery);
// UI of gallery display. Initializes the GridView and ItemView
// classes. Then wait for interaction from user.
GridView gal = (GridView) findViewById(R.id.gridView);
final ImageView imageView = (ImageView) findViewById(R.id.imageSelected);
// Calls the ImageAdapter Class.
gal.setAdapter(new ImageAdapter(this));
// Calls the onItemClickListener Class
gal.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
/* onItemClick Method
The onItemClick method has four arguments.
AdapterView<?> arg0 - Records where the user touched screen
View arg1 - Parameters of the View user touched
int arg2 - Integer value that holds the position of the View
in the adapter.
long arg3 - Determines the row id of the item that was
selected by the user.
*/
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
Toast.makeText(getBaseContext(), "You have selected picture " + (arg2 + 1)
+ "Brien Calloway", Toast.LENGTH_SHORT).show();
imageView.setImageResource(Profile[arg2]);
}
});
}
public class ImageAdapter extends BaseAdapter{
private Context context;
public ImageAdapter(Context c){
context=c;
}
public ImageAdapter(PictureGallery pictureGallery) {
}
@Override
public int getCount() {return Profile.length;}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return 0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ImageView pic = new ImageView(context);
pic.setImageResource(Profile[arg0]);
pic.setScaleType(ImageView.ScaleType.FIT_XY);
pic.setLayoutParams(new GridView.LayoutParams(200,175));
return pic;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_picture_gallery, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
LOGCAT
OpenGL ES Shader Compiler Version: E031.24.00.07
Build Date: 01/22/14 Wed
Local Branch: base_au149_adreno_au169_patches
Remote Branch:
Local Patches:
Reconstruct Branch:
01-12 16:21:20.914 24367-24367/com.gallery.brien.picturegallery D/OpenGLRenderer﹕ Enabling debug mode 0
01-12 16:21:53.704 24367-24367/com.gallery.brien.picturegallery W/ApplicationPackageManager﹕ getCSCPackageItemText()
01-12 16:21:53.734 24367-24367/com.gallery.brien.picturegallery E/MoreInfoHPW_ViewGroup﹕ Parent view is not a TextView
01-12 16:21:53.784 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ Get MotionRecognitionManager
01-12 16:21:53.804 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ onVisibilityChanged() is called, visibility : 4
01-12 16:21:53.804 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.814 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ onVisibilityChanged() is called, visibility : 0
01-12 16:21:53.814 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.834 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.844 24367-24367/com.gallery.brien.picturegallery D/AndroidRuntime﹕ Shutting down VM
01-12 16:21:53.844 24367-24367/com.gallery.brien.picturegallery W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x42068da0)
01-12 16:21:53.864 24367-24367/com.gallery.brien.picturegallery E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.gallery.brien.picturegallery, PID: 24367
java.lang.NullPointerException
at android.view.ViewConfiguration.get(ViewConfiguration.java:329)
at android.view.View.<init>(View.java:3578)
at android.widget.ImageView.<init>(ImageView.java:118)
at com.gallery.brien.picturegallery.PictureGallery$ImageAdapter.getView(PictureGallery.java:85)
at android.widget.AbsListView.obtainView(AbsListView.java:2733)
at android.widget.GridView.onMeasure(GridView.java:1049)
at android.view.View.measure(View.java:17367)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:382)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2505)
at android.view.View.measure(View.java:17367)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2174)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1315)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1512)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1199)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6383)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:803)
at android.view.Choreographer.doCallbacks(Choreographer.java:603)
at android.view.Choreographer.doFrame(Choreographer.java:573)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:789)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:157)
at android.app.ActivityThread.main(ActivityThread.java:5293)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
at dalvik.system.NativeStart.main(Native Method)
01-12 16:26:54.014 24367-24367/com.gallery.brien.picturegallery I/Process﹕ Sending signal. PID: 24367 SIG: 9
删除行：
public ImageAdapter(PictureGallery pictureGallery) {
}
您正在调用此构造函数，而您的上下文为空。
你的 ImageAdapter 是用它的第二个构造函数构造的，它没有设置上下文。 null 上下文导致 NullPointerException 稍后在 ImageView 构造函数中，它在 getView.
中调用
更改构造函数以设置上下文或完全删除构造函数。
我的 Android 应用程序 (AA) 出现致命异常：main java.lang.NullPointerException。我的 AA 有两个活动，第一个屏幕是基本配置文件主屏幕，第二个是图片库。我还不是很擅长调试，所以我无法弄清楚为什么第二个 activity 强制关闭 (FC)。
你能给我指出正确的方向吗？
主要Activity
package com.gallery.brien.picturegallery;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Picture;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class Main extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void changePicture(View view) {
/* Open picture gallery activity */
Intent intent = new Intent(this,PictureGallery.class);
startActivity(intent);
}
}
第二个Activity
package com.gallery.brien.picturegallery;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;
public class PictureGallery extends Activity {
//variable array where pictures are store
Integer[] Profile = {R.drawable.brien, R.drawable.kick, R.drawable.mma, R.drawable.fun,
R.drawable.run};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.picture_gallery);
// UI of gallery display. Initializes the GridView and ItemView
// classes. Then wait for interaction from user.
GridView gal = (GridView) findViewById(R.id.gridView);
final ImageView imageView = (ImageView) findViewById(R.id.imageSelected);
// Calls the ImageAdapter Class.
gal.setAdapter(new ImageAdapter(this));
// Calls the onItemClickListener Class
gal.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
/* onItemClick Method
The onItemClick method has four arguments.
AdapterView<?> arg0 - Records where the user touched screen
View arg1 - Parameters of the View user touched
int arg2 - Integer value that holds the position of the View
in the adapter.
long arg3 - Determines the row id of the item that was
selected by the user.
*/
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
Toast.makeText(getBaseContext(), "You have selected picture " + (arg2 + 1)
+ "Brien Calloway", Toast.LENGTH_SHORT).show();
imageView.setImageResource(Profile[arg2]);
}
});
}
public class ImageAdapter extends BaseAdapter{
private Context context;
public ImageAdapter(Context c){
context=c;
}
public ImageAdapter(PictureGallery pictureGallery) {
}
@Override
public int getCount() {return Profile.length;}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return 0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ImageView pic = new ImageView(context);
pic.setImageResource(Profile[arg0]);
pic.setScaleType(ImageView.ScaleType.FIT_XY);
pic.setLayoutParams(new GridView.LayoutParams(200,175));
return pic;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_picture_gallery, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
LOGCAT
OpenGL ES Shader Compiler Version: E031.24.00.07
Build Date: 01/22/14 Wed
Local Branch: base_au149_adreno_au169_patches
Remote Branch:
Local Patches:
Reconstruct Branch:
01-12 16:21:20.914 24367-24367/com.gallery.brien.picturegallery D/OpenGLRenderer﹕ Enabling debug mode 0
01-12 16:21:53.704 24367-24367/com.gallery.brien.picturegallery W/ApplicationPackageManager﹕ getCSCPackageItemText()
01-12 16:21:53.734 24367-24367/com.gallery.brien.picturegallery E/MoreInfoHPW_ViewGroup﹕ Parent view is not a TextView
01-12 16:21:53.784 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ Get MotionRecognitionManager
01-12 16:21:53.804 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ onVisibilityChanged() is called, visibility : 4
01-12 16:21:53.804 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.814 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ onVisibilityChanged() is called, visibility : 0
01-12 16:21:53.814 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.834 24367-24367/com.gallery.brien.picturegallery D/AbsListView﹕ unregisterIRListener() is called
01-12 16:21:53.844 24367-24367/com.gallery.brien.picturegallery D/AndroidRuntime﹕ Shutting down VM
01-12 16:21:53.844 24367-24367/com.gallery.brien.picturegallery W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x42068da0)
01-12 16:21:53.864 24367-24367/com.gallery.brien.picturegallery E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.gallery.brien.picturegallery, PID: 24367
java.lang.NullPointerException
at android.view.ViewConfiguration.get(ViewConfiguration.java:329)
at android.view.View.<init>(View.java:3578)
at android.widget.ImageView.<init>(ImageView.java:118)
at com.gallery.brien.picturegallery.PictureGallery$ImageAdapter.getView(PictureGallery.java:85)
at android.widget.AbsListView.obtainView(AbsListView.java:2733)
at android.widget.GridView.onMeasure(GridView.java:1049)
at android.view.View.measure(View.java:17367)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:382)
at android.view.View.measure(View.java:17367)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2505)
at android.view.View.measure(View.java:17367)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2174)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1315)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1512)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1199)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6383)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:803)
at android.view.Choreographer.doCallbacks(Choreographer.java:603)
at android.view.Choreographer.doFrame(Choreographer.java:573)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:789)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:157)
at android.app.ActivityThread.main(ActivityThread.java:5293)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
at dalvik.system.NativeStart.main(Native Method)
01-12 16:26:54.014 24367-24367/com.gallery.brien.picturegallery I/Process﹕ Sending signal. PID: 24367 SIG: 9
删除行：
public ImageAdapter(PictureGallery pictureGallery) {
}
您正在调用此构造函数，而您的上下文为空。
你的 ImageAdapter 是用它的第二个构造函数构造的，它没有设置上下文。 null 上下文导致 NullPointerException 稍后在 ImageView 构造函数中，它在 getView.
更改构造函数以设置上下文或完全删除构造函数。