我正在试验SharedPreferences，但我遇到了一些困难。
在我的活动中，我需要在点击SharedPreferences并且解决方案正确时调用我的Button。检查我的解决方案是否正确无法正常工作，只要我调用NullPointerException，应用就会遇到SharedPreferences。任何提示？
这是我的活动：
package com.mitonanetherlands.buttonchooser;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public class LevelFour_1 extends Activity {
MoPubView ad1,ad2;
TextView Level;
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and width
final int heightRatio = Math.round((float) height / (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value, this will guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
ImageView person1,person2,person3,person4,person5,person6;
ImageView slot1,slot2,slot3,slot4,slot5,slot6;
ImageView Appartementen;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.level_sjabloon);
Level = (TextView) findViewById(R.id.SjabloonText);
Level.setText("Level 4-1");
ad1 = (MoPubView) findViewById(R.id.LevelLeftTop);
ad2 = (MoPubView) findViewById(R.id.LevelRightTop);
ad1.setAdUnitId("4f53c030c3e211e295fa123138070049");
ad2.setAdUnitId("1abf4e6ac3e311e295fa123138070049");
ad1.loadAd();
ad2.loadAd();
person1 = (ImageView) findViewById(R.id.Person1);
person2 = (ImageView) findViewById(R.id.Person2);
person3 = (ImageView) findViewById(R.id.Person3);
person4 = (ImageView) findViewById(R.id.Person4);
person5 = (ImageView) findViewById(R.id.Person5);
person6 = (ImageView) findViewById(R.id.Person6);
slot1 = (ImageView) findViewById(R.id.Slot1);
slot2 = (ImageView) findViewById(R.id.Slot2);
slot3 = (ImageView) findViewById(R.id.Slot3);
slot4 = (ImageView) findViewById(R.id.Slot4);
slot5 = (ImageView) findViewById(R.id.Slot5);
slot6 = (ImageView) findViewById(R.id.Slot6);
Appartementen = (ImageView) findViewById(R.id.AppartementenComplex);
Button submit = (Button) findViewById(R.id.SubmitButton);
Button reset = (Button) findViewById(R.id.Reset);
person1.setOnTouchListener(new ChoiceTouchListener());
person2.setOnTouchListener(new ChoiceTouchListener());
person3.setOnTouchListener(new ChoiceTouchListener());
person4.setOnTouchListener(new ChoiceTouchListener());
person5.setOnTouchListener(new ChoiceTouchListener());
person6.setOnTouchListener(new ChoiceTouchListener());
slot1.setOnDragListener(new ChoiceDragListener());
slot2.setOnDragListener(new ChoiceDragListener());
slot3.setOnDragListener(new ChoiceDragListener());
slot4.setOnDragListener(new ChoiceDragListener());
slot5.setOnDragListener(new ChoiceDragListener());
slot6.setOnDragListener(new ChoiceDragListener());
person1.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.bea,300,450));
person2.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.eline,300,450));
person3.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.guido,300,450));
person4.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.pierre,300,450));
//person5.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.rosalinda,300,450));
//person6.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.wong,300,450));
person1.setTag(R.drawable.bea);
person2.setTag(R.drawable.eline);
person3.setTag(R.drawable.guido);
person4.setTag(R.drawable.pierre);
//person5.setTag(R.drawable.rosalinda);
//person6.setTag(R.drawable.wong);
Appartementen.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.huisje,300,450));
submit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
if(Integer.parseInt(slot1.getTag().toString()) == R.drawable.guido && slot2.getTag() == null &&
Integer.parseInt(slot3.getTag().toString()) == R.drawable.bea && Integer.parseInt(slot4.getTag().toString()) == R.drawable.eline &&
slot5.getTag() == null && Integer.parseInt(slot6.getTag().toString()) == R.drawable.pierre){
Toast.makeText(getApplicationContext(), "Your solution is correct! Unlocking next level...", Toast.LENGTH_SHORT).show();
SharedPreferences completedLevels = LevelFour_1.this.getSharedPreferences("com.mitonanetherlands.buttonchooser", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = completedLevels.edit();
editor.putBoolean("Level 4-1", true).apply();
editor.putString("Last Completed", "4-1").apply();
startActivity(new Intent("com.mitonanetherlands.buttonchooser.L4_2"));
// }else{
if(person1.getVisibility() == View.INVISIBLE){
person1.setVisibility(View.VISIBLE);
};if(person2.getVisibility() == View.INVISIBLE){
person2.setVisibility(View.VISIBLE);
};if(person3.getVisibility() == View.INVISIBLE){
person3.setVisibility(View.VISIBLE);
};if(person4.getVisibility() == View.INVISIBLE){
person4.setVisibility(View.VISIBLE);
};if(person5.getVisibility() == View.INVISIBLE){
person5.setVisibility(View.VISIBLE);
};if(person6.getVisibility() == View.INVISIBLE){
person6.setVisibility(View.VISIBLE);};
slot1.setImageBitmap(null);
slot1.setTag(null);
slot2.setImageBitmap(null);
slot2.setTag(null);
slot3.setImageBitmap(null);
slot3.setTag(null);
slot4.setImageBitmap(null);
slot4.setTag(null);
slot5.setImageBitmap(null);
slot5.setTag(null);
slot6.setImageBitmap(null);
slot6.setTag(null);
Toast.makeText(getApplicationContext(), "Wrong! Resetting...", Toast.LENGTH_SHORT).show();
// }
}
}});
reset.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(person1.getVisibility() == View.INVISIBLE){
person1.setVisibility(View.VISIBLE);
};if(person2.getVisibility() == View.INVISIBLE){
person2.setVisibility(View.VISIBLE);
};if(person3.getVisibility() == View.INVISIBLE){
person3.setVisibility(View.VISIBLE);
};if(person4.getVisibility() == View.INVISIBLE){
person4.setVisibility(View.VISIBLE);
};if(person5.getVisibility() == View.INVISIBLE){
person5.setVisibility(View.VISIBLE);
};if(person6.getVisibility() == View.INVISIBLE){
person6.setVisibility(View.VISIBLE);};
slot1.setImageBitmap(null);
slot1.setTag(null);
slot2.setImageBitmap(null);
slot2.setTag(null);
slot3.setImageBitmap(null);
slot3.setTag(null);
slot4.setImageBitmap(null);
slot4.setTag(null);
slot5.setImageBitmap(null);
slot5.setTag(null);
slot6.setImageBitmap(null);
slot6.setTag(null);
}
});
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private final class ChoiceTouchListener implements OnTouchListener {
public boolean onTouch(View view, MotionEvent motionEvent) {
if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
/*
* Drag details: we only need default behavior
* - clip data could be set to pass data as part of drag
* - shadow can be tailored
*/
ClipData data = ClipData.newPlainText("", "");
DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
//start dragging the item touched
view.startDrag(data, shadowBuilder, view, 0);
return true;
} else {
return false;
}
}
}
private class ChoiceDragListener implements OnDragListener {
@Override
public boolean onDrag(View v, DragEvent event) {
switch (event.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
//no action necessary
break;
case DragEvent.ACTION_DRAG_ENTERED:
//no action necessary
break;
case DragEvent.ACTION_DRAG_EXITED:
//no action necessary
break;
case DragEvent.ACTION_DROP:
//handle the dragged view being dropped over a drop view
View view = (View) event.getLocalState();
//stop displaying the view where it was before it was dragged
view.setVisibility(View.INVISIBLE);
//view dragged item is being dropped on
ImageView dropTarget = (ImageView) v;
//view being dragged and dropped
ImageView dropped = (ImageView) view;
int plaatje = (Integer) view.getTag();
Object tag = dropTarget.getTag();
//if there is already an item here, set it back visible in its original place
if(tag!=null)
{
//the tag is the view id already dropped here
int existingID = (Integer)tag;
//set the original view visible again
findViewById(existingID).setVisibility(View.VISIBLE);
}
//set the tag in the target view being dropped on - to the ID of the view being dropped
dropTarget.setImageBitmap(decodeSampledBitmapFromResource(getResources(),plaatje,100,150));
dropTarget.setTag(dropped.getId());
break;
case DragEvent.ACTION_DRAG_ENDED:
//no action necessary
break;
default:
break;
}
return true;
}
}
@Override
protected void onPause() {
super.onPause();
ad1.destroy();
ad2.destroy();
}
@Override
protected void onDestroy() {
super.onDestroy();
ad1.destroy();
ad2.destroy();
}
}
这是LogCat：
05-27 13:47:03.974: E/AndroidRuntime(17912): FATAL EXCEPTION: main
05-27 13:47:03.974: E/AndroidRuntime(17912): java.lang.NullPointerException
05-27 13:47:03.974: E/AndroidRuntime(17912): at com.mitonanetherlands.buttonchooser.LevelFour_1$1.onClick(LevelFour_1.java:144)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.view.View.performClick(View.java:4223)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.view.View$PerformClick.run(View.java:17275)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.os.Handler.handleCallback(Handler.java:615)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.os.Handler.dispatchMessage(Handler.java:92)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.os.Looper.loop(Looper.java:137)
05-27 13:47:03.974: E/AndroidRuntime(17912): at android.app.ActivityThread.main(ActivityThread.java:4898)
05-27 13:47:03.974: E/AndroidRuntime(17912): at java.lang.reflect.Method.invokeNative(Native Method)
05-27 13:47:03.974: E/AndroidRuntime(17912): at java.lang.reflect.Method.invoke(Method.java:511)
05-27 13:47:03.974: E/AndroidRuntime(17912): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1008)
05-27 13:47:03.974: E/AndroidRuntime(17912): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:775)
05-27 13:47:03.974: E/AndroidRuntime(17912): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
您正在尝试使用尚未设置的值。在使用getTag()之前，您应该为Object设置一些有效的slot1引用作为标记。
无论在何处实例化，都可以将标记设置为slot1。
这是您从slot1获取标记值时NullPointerException（第144行）获取onClick()的原因。此外，我发现您将null设置为第1行中slot1的标记。 167：
slot1.setTag(null);
如果在此之前未设置正确的标记，则在获取slot1的标记时将再次生成NullPointerException。
的解决方案： 的
每当对Object使用setTag()时，必须传递有效的View引用。更多信息 here 。
答案 1 :(得分：0)
需要提交该编辑器
editor.putString("Last Completed", "4-1");
editor.commit();