我在这里查看了很多其他问题，但似乎没有一个对我有帮助。我正在编写一个应用程序，您可以在其中按下按钮打开相机。这工作正常，但我一去保存图片它就崩溃了，我得到了那个错误。 到目前为止，这是我的代码
public class MainActivity extends Activity {
private int TAKE_PICTURE = 1337;
private Uri outputFileUri;
private int screenHeight;
private int screenWidth;
private ImageView background;
private String ORIGINAL_FILE = "photo.jpg";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button take = (Button)findViewById(R.id.take);
Button share = (Button)findViewById(R.id.share);
take.setOnClickListener(new takeInstr(this));
ImageView background = (ImageView)findViewById(R.id.background);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public void startCamera() {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
File file = new File(Environment.getExternalStorageDirectory(), ORIGINAL_FILE);
outputFileUri = Uri.fromFile(file);
intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
startActivityForResult(intent, TAKE_PICTURE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == TAKE_PICTURE && resultCode != RESULT_CANCELED) {
if (data != null) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
String file = Environment.getExternalStorageDirectory() + "/test.jpg";
BitmapFactory.decodeFile(file, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
DisplayMetrics metrics = this.getResources().getDisplayMetrics();
screenHeight = metrics.heightPixels;
screenWidth = metrics.widthPixels;
int heightRatio = Math.round((float) imageHeight / (float) screenHeight);
int widthRatio = Math.round((float) imageWidth / (float) screenWidth);
options.inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
options.inJustDecodeBounds = false;
background.setImageBitmap(BitmapFactory.decodeFile(file, options));
}
else {
}
}
}
}
package com.example.photoshare;
import android.view.View;
import android.view.View.OnClickListener;
public class takeInstr implements OnClickListener {
private MainActivity mainActivity;
public takeInstr(MainActivity mainActivity) {
this.mainActivity = mainActivity;
}
@Override
public void onClick(View v) {
mainActivity.startCamera();
}
}
`
我的xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<ImageView
android:id="@+id/background"
android:src="@drawable/great_wall"
android:layout_width="fill_parent"
android:scaleType="fitXY"
android:layout_height="fill_parent" />
<LinearLayout
android:id="@+id/buttonLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:gravity="center_horizontal"
android:weightSum="1.0" >
<Button
android:id="@+id/take"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="0.5"
android:text="@string/take" />
<Button
android:id="@+id/share"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="0.5"
android:text="@string/share" />
</LinearLayout>
这是我的 logcat 消息
02-18 12:42:56.266: W/dalvikvm(627): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
02-18 12:42:56.357: E/AndroidRuntime(627): FATAL EXCEPTION: main
02-18 12:42:56.357: E/AndroidRuntime(627): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1337, result=-1, data=null} to activity {com.example.photoshare/com.example.photoshare.MainActivity}: java.lang.NullPointerException
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread.deliverResults(ActivityThread.java:2980)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3023)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread.access$1100(ActivityThread.java:123)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1177)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.os.Handler.dispatchMessage(Handler.java:99)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.os.Looper.loop(Looper.java:137)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread.main(ActivityThread.java:4424)
02-18 12:42:56.357: E/AndroidRuntime(627): at java.lang.reflect.Method.invokeNative(Native Method)
02-18 12:42:56.357: E/AndroidRuntime(627): at java.lang.reflect.Method.invoke(Method.java:511)
02-18 12:42:56.357: E/AndroidRuntime(627): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-18 12:42:56.357: E/AndroidRuntime(627): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-18 12:42:56.357: E/AndroidRuntime(627): at dalvik.system.NativeStart.main(Native Method)
02-18 12:42:56.357: E/AndroidRuntime(627): Caused by: java.lang.NullPointerException
02-18 12:42:56.357: E/AndroidRuntime(627): at com.example.photoshare.MainActivity.onActivityResult(MainActivity.java:69)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.Activity.dispatchActivityResult(Activity.java:4649)
02-18 12:42:56.357: E/AndroidRuntime(627): at android.app.ActivityThread.deliverResults(ActivityThread.java:2976)
02-18 12:42:56.357: E/AndroidRuntime(627): ... 11 more
02-18 12:42:56.686: I/dalvikvm(627): threadid=3: reacting to signal 3
02-18 12:42:56.726: I/dalvikvm(627): Wrote stack traces to '/data/anr/traces.txt'
02-18 12:42:57.047: I/dalvikvm(627): threadid=3: reacting to signal 3
02-18 12:42:57.086: I/dalvikvm(627): Wrote stack traces to '/data/anr/traces.txt'
02-18 12:42:59.716: I/Process(627): Sending signal. PID: 627 SIG: 9
我知道当它返回 null 时我应该做一些其他事情，但我不知道该做什么，我们将不胜感激所有帮助。
最佳答案
您的代码中有两个不同的东西可能为空。第一个可能是 BitmapFactory 无法解码您提供的文件的问题。另外你确定你只想解码 test.jpg 而不是相机拍摄的吗？
第二个可能是您的背景 View 的问题。根据您 Activity 的启动类型，它 might happen onActivityResult() 在 onCreate() 之前被调用，这将导致 background 变量仍然为 null。
要深入挖掘，您应该将解码后的位图分配给一个新变量并查看它是否为 null 并检查 background 是否为 null...
关于android - 使用相机后，我的 android 应用程序中的 onActivityResult 出现 NullPointerException 和 Failure Delivering Result 异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14941850/