我正在尝试Activity
使用Intent
. 我已经在另一个应用程序中成功完成了这项工作,但这种方法在这种情况下似乎不起作用?
这是我的代码...
public void startLevelEnd(Context context){
Intent myIntent = new Intent(FirstActivity.this, LevelEndPanel.class);
FirstActivity.this.startActivity(myIntent);
}
从我的AndroidManifest.xml
档案...
<activity android:label="@string/app_name" android:name=".LevelEndPanel"></activity>
我startLevelEnd()
使用...调用例程(来自不同的类)
FirstActivity.startLevelEnd(this);
我NullPointerException
在“Intent myIntent ...”行(来自上面的代码片段)上收到错误:
04-16 09:46:39.361: E/AndroidRuntime(475): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120)
完整日志:
04-16 14:32:32.870: E/AndroidRuntime(336): FATAL EXCEPTION: main
04-16 14:32:32.870: E/AndroidRuntime(336): java.lang.NullPointerException
04-16 14:32:32.870: E/AndroidRuntime(336): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.content.ComponentName.<init>(ComponentName.java:75)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.content.Intent.<init>(Intent.java:2702)
04-16 14:32:32.870: E/AndroidRuntime(336): at happyworx.nl.App.FirstActivity.startLevelEnd(FirstActivity.java:32)
04-16 14:32:32.870: E/AndroidRuntime(336): at happyworx.nl.App.model.components.GameManager.LevelEnd(GameManager.java:89)
04-16 14:32:32.870: E/AndroidRuntime(336): at happyworx.nl.App.model.components.GameManager$1.run(GameManager.java:60)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.os.Handler.handleCallback(Handler.java:587)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.os.Handler.dispatchMessage(Handler.java:92)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.os.Looper.loop(Looper.java:123)
04-16 14:32:32.870: E/AndroidRuntime(336): at android.app.ActivityThread.main(ActivityThread.java:3683)
04-16 14:32:32.870: E/AndroidRuntime(336): at java.lang.reflect.Method.invokeNative(Native Method)
04-16 14:32:32.870: E/AndroidRuntime(336): at java.lang.reflect.Method.invoke(Method.java:507)
04-16 14:32:32.870: E/AndroidRuntime(336): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-16 14:32:32.870: E/AndroidRuntime(336): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-16 14:32:32.870: E/AndroidRuntime(336): at dalvik.system.NativeStart.main(Native Method)
对于@Sergi,包含该方法的完整类:
package happyworx.nl.Appelz.model.components;
import happyworx.nl.Appelz.AppelzActivity;
import happyworx.nl.Appelz.LevelEndPanel;
import happyworx.nl.Appelz.MainGamePanel;
import happyworx.nl.Appelz.MainThread;
import happyworx.nl.Appelz.R;
import happyworx.nl.Appelz.model.apple;
import happyworx.nl.Appelz.model.glyphs;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import android.app.Activity;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.os.Handler;
import android.util.Log;
public class GameManager extends Activity {
//Declare Vars
private static final String TAG = "GameManager";
public static MainGamePanel panel;
private static glyphs glyphsCount;
public static GameManager GameManager = new GameManager();
public static AppelzActivity AppelzActivity = new AppelzActivity();
private static Canvas canvas;
final static int delayMillis = 1000;
public static boolean count = false;
public static int i = 6;
public final static Handler handler = new Handler();
public final static Runnable runnable = new Runnable() {
@Override
public void run()
{
if (SlotManager.alSlottedFruitList.size() > 0){
//TODO Create Full screen countdown timer
Log.d("", "Countdown Timer in GameManager " + i);
i--;
if (count && i > -1) // stop timer when count is false
{
handler.postDelayed(runnable, 1000);
} else {
if (i == -1){
Log.d("", "RoundUp the Level");
GameManager.LevelEnd();
}
// reset Countdown (if basket outside checkout)
i = 6;
}
} else {
// reset Countdown (if slot has no fruits)
i = 6;
}
}
};
public void LevelEnd(){
// First, count the Fruits in the slot
SlotManager.countSlotInv();
List<Integer> list = new ArrayList<Integer>();
// Fill itemIds with the types of fruits
for (apple a : SlotManager.alSlottedFruitList){
Integer itemId = Integer.valueOf(a.FruitType);
list.add(itemId);
Set<Integer> unique = new HashSet<Integer>(list);
}
for (int key = 0; key < 3 ; key++) {
System.out.println(key + " : " + Collections.frequency(list, key));
}
startLevelEnd();
}
public void startLevelEnd(){
Intent myIntent = new Intent(this, LevelEndPanel.class);
this.startActivity(myIntent);
}
public GameManager()
{
}
LevelEndPanel 类:
package happyworx.nl.Appelz;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class LevelEndPanel extends Activity implements OnClickListener {
private static final String TAG = LevelEndPanel.class.getSimpleName();
private Button btnNewMission;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.level);
btnNewMission = (Button) findViewById(R.id.btnNewMission);
btnNewMission.setOnClickListener(new Button.OnClickListener() {
public void onClick(View arg0) {
Intent i = new Intent(getApplicationContext(), AppelzActivity.class);
startActivity(i);
}});
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
和主线程:
package happyworx.nl.Appelz;
import android.graphics.Canvas;
import android.util.Log;
import android.view.SurfaceHolder;
public class MainThread extends Thread {
private static final String TAG = MainThread.class.getSimpleName();
private SurfaceHolder surfaceHolder;
private MainGamePanel gamePanel;
public static boolean running;
public static Canvas canvas;
public void setRunning(boolean running) {
MainThread.running = running;
}
public MainThread(SurfaceHolder surfaceHolder, MainGamePanel gamePanel) {
super();
this.surfaceHolder = surfaceHolder;
this.gamePanel = gamePanel;
}
@Override
public void run() {
// Canvas canvas;
Log.d(TAG, "Starting game loop");
while (running) {
MainThread.canvas = null;
// try locking the canvas for exclusive pixel editing on the surface
try {
MainThread.canvas = this.surfaceHolder.lockCanvas();
synchronized (surfaceHolder) {
// update game state
this.gamePanel.update();
// render state to the screen
// draws the canvas on the panel
this.gamePanel.onDraw(MainThread.canvas);
}
} finally {
// in case of an exception the surface is not left in
// an inconsistent state
if (MainThread.canvas != null) {
surfaceHolder.unlockCanvasAndPost(MainThread.canvas);
}
} // end finally
}
}
}
还有篮子类,它在 GameManager 中启动 CountDown 计时器(也许这是我的错误?!?)
package happyworx.nl.Appelz.model;
import happyworx.nl.Appelz.MainGamePanel;
import happyworx.nl.Appelz.model.components.GameManager;
import happyworx.nl.Appelz.model.components.SlotManager;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.util.Log;
import android.view.MotionEvent;
public class basket {
private Bitmap bitmap; // the actual bitmap
private int x; // the X coordinate
private int y; // the Y coordinate'
public static int width;
public static int height;
public float X = 100;
public float Y = 100;
private boolean touched; // if droid is touched/picked up
public basket(Bitmap bitmap, int x, int y) {
this.bitmap = bitmap;
width = bitmap.getWidth();
height = bitmap.getHeight();
}
public Bitmap getBitmap() {
return bitmap;
}
public void setBitmap(Bitmap bitmap) {
this.bitmap = bitmap;
}
public int getWidth(){
return bitmap.getWidth();
}
public int getHeight(){
return bitmap.getHeight();
}
public int getX() {
return x;
}
public void setX(float x) {
// if basket is further than slotmargin
if (x + width/2 > SlotManager.SlotmarginX) {
// if basket is NOT in CheckOut area
if (this.Y < MainGamePanel.height - 80 - height/2){
x = SlotManager.SlotmarginX - width/2;
} else {
// if basket IS in CheckOut area
x = MainGamePanel.width - width/2;
// Start the countdown timer if not already running
if (!GameManager.count){
GameManager.count=true;
GameManager.handler.postDelayed(GameManager.runnable, 0);
}
}
} else {
// Basket is NOT in CheckOut area; stop countdown timer
GameManager.count=false;
}
this.X = x;
}
public int getY() {
return y;
}
public void setY(int y) {
if (y + height/2 > MainGamePanel.height - 80){
y = MainGamePanel.height - 80 - height/2;
}
this.Y = y;
}
public boolean isTouched() {
return touched;
}
public void setTouched(boolean touched) {
this.touched = touched;
}
public void draw(Canvas canvas) {
canvas.drawBitmap(bitmap, X - width/2, Y - height/2, null);
}
public void handleActionDown(int eventX, int eventY) {
if (eventX >= (X - width/ 2) && (eventX <= (X + width/2))) {
if (eventY >= (Y - height/ 2) && (eventY <= (Y + height/ 2))) {
// basket touched
setTouched(true);
} else {
setTouched(false);
}
} else {
setTouched(false);
}
}
}