MainActivity代码： 公共类MainActivity扩展Activity实现OnClickListener {
ImageView display;
int toPhone;
private Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
System.gc();
context = this;
toPhone = R.drawable.wal1;
display = (ImageView) findViewById(R.id.WPdisplay);
ImageView image1 = (ImageView) findViewById(R.id.WPimg1);
ImageView image2 = (ImageView) findViewById(R.id.WPimg2);
ImageView image3 = (ImageView) findViewById(R.id.WPimg3);
ImageView image4 = (ImageView) findViewById(R.id.WPimg4);
ImageView image5 = (ImageView) findViewById(R.id.WPimg5);
Button setWall = (Button) findViewById(R.id.BsetWall);
image1.setOnClickListener(this);
image2.setOnClickListener(this);
image3.setOnClickListener(this);
image4.setOnClickListener(this);
image5.setOnClickListener(this);
setWall.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public Bitmap decodeAndResizeFile(int resID) {
try {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
我认为在下一行我有一个问题，因为它说没有使用局部变量bmp的值
Bitmap bmp= BitmapFactory.decodeResource(context.getResources(), resID, o);
// BitmapFactory.decodeStream(new FileInputStream(f), null, o);
// The new size we want to scale to
final int REQUIRED_SIZE = 70;
// Find the correct scale value. It should be the power of 2.
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
return BitmapFactory.decodeResource(context.getResources(), resID, o2);
} finally {
}
}
@Override
public void onClick(View v) {
Bitmap bmpp;
switch (v.getId()){
case R.id.WPimg1:
display.setImageResource(R.drawable.wal1);
toPhone = R.drawable.wal1;
在下一行我试图解码它（我正在为每个图像做这个）
bmpp = decodeAndResizeFile(toPhone);
//Bitmap bmpp = decodeAndResizeFile(file);
break;
case R.id.WPimg2:
display.setImageResource(R.drawable.wal2);
toPhone = R.drawable.wal2;
bmpp = decodeAndResizeFile(toPhone);
display.setImageBitmap(bmpp);
break;
case R.id.WPimg3:
display.setImageResource(R.drawable.wal3);
toPhone = R.drawable.wal3;
bmpp = decodeAndResizeFile(toPhone);
break;
case R.id.WPimg4:
display.setImageResource(R.drawable.wal4);
toPhone = R.drawable.wal4;
bmpp = decodeAndResizeFile(toPhone);
break;
case R.id.WPimg5:
display.setImageResource(R.drawable.wal5);
toPhone = R.drawable.wal5;
bmpp = decodeAndResizeFile(toPhone);
break;
case R.id.BsetWall:
try{
WallpaperManager.getInstance(getApplicationContext()).setResource(toPhone);
Toast.makeText(getApplicationContext(), "Wallpaper was set!", Toast.LENGTH_SHORT).show();
} catch(IOException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "No privileges!", Toast.LENGTH_SHORT).show();
}
break;
}
}
}
这是我的Logcat
--- decoder->decode returned false
Shutting down VM
threadid=1: thread exiting with uncaught exception (group=0xb3adbba8)
FATAL EXCEPTION: main
Process: app.technozed.testwall, PID: 1250
java.lang.RuntimeException: Unable to start activity ComponentInfo{app.technozed.testwall/app.technozed.testwall.MainActivity}: android.view.InflateException: Binary XML file line #304: Error inflating class <unknown>
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
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:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #304: Error inflating class <unknown>
at android.view.LayoutInflater.createView(LayoutInflater.java:620)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:669)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:694)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
at android.app.Activity.setContentView(Activity.java:1929)
at app.technozed.testwall.MainActivity.onCreate(MainActivity.java:28)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
... 11 more
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.view.LayoutInflater.createView(LayoutInflater.java:594)
... 26 more
Caused by: java.lang.OutOfMemoryError
at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)
at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:587)
at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:422)
at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:840)
at android.content.res.Resources.loadDrawable(Resources.java:2110)
at android.content.res.TypedArray.getDrawable(TypedArray.java:602)
at android.widget.ImageView.<init>(ImageView.java:129)
at android.widget.ImageView.<init>(ImageView.java:119)
... 29 more
答案 0 :(得分：1)
如果您在decodeAndResizeFile（）中收到警告'未使用局部变量bmp的值'，则可以删除'Bitmap bmp ='部分并将其保留为：
BitmapFactory.decodeResource(context.getResources(), resID, o);
这是因为此调用是使用o.inJustDecodeBounds = true。在这种情况下，只在对象'o'中返回维度并返回一个空位图（因此没有点存储它）。
在您的switch语句中，将每个案例更改为如下所示：
case R.id.WPimg1:
toPhone = R.drawable.wal1;
bmpp = decodeAndResizeFile(toPhone);
display.setImageBitmap(bmpp);
break;
所以在这里，您将资源解码为缩小的位图，然后将该位图分配给ImageView。您不希望或不需要这样做：
display.setImageResource(R.drawable.wal1);
...因为你冒着OutOfMemoryException的风险，所以你继续用缩放的位图设置'display'。完成这些更改后，您的代码就适合我。我可以看到壁纸预览图像，然后设置壁纸（不要忘记清单中的SET_WALLPAPER权限）。
然而，这并没有解释你的logcat，它似乎是onCreate（）膨胀R.layout.activity_main的一个问题。在logcat的末尾，它再次显示OutOfMemoryError。如果我将一个大的jpg分配给XML中的ImageView（OOM结果，因此布局不能膨胀），我可以重新创建此错误。当用XML分配drawable时，你无法“动态”缩小它们，因此创建物理上较小的drawable以便在XML中使用。
编辑：
当您点击图片时，'display'会获得一个新的位图，而旧的位图符合GC的条件。这是一种方法，可以立即释放旧存储器使用的内存，而无需等待GC启动：
将此项从onClick（）移动为类变量：
Bitmap bmpp; //Reference to the same bitmap that 'display' is using
然后在onClick（）：
Bitmap old_bm = null; //Reference to hold the old bitmap
switch (v.getId()){
case R.id.WPimg1:
old_bm = bmpp; //Set to the bitmap currently being used by 'display'
toPhone = R.drawable.wal1;
bmpp = decodeAndResizeFile(toPhone); //'display' now has a new bitmap
display.setImageBitmap(bmpp);
if (old_bm != null)
{
old_bm.recycle(); //Recyle the old bitmap
old_bm = null; //Clear the reference to allow GC to clean up fully
}
break;