所以基本上我希望应用程序:按下按钮打开图库后,用户选择一个图像,然后将uri保存在变量中。这就是它需要做的,但我发现在调用startActivityForResult()之后,后续代码仍会在后台运行,从而创建NullPointerException错误,因为我想要的变量尚未从意图中检索。调用startActivityForResult()后,后续代码仍然运行
public class MainActivity extends AppCompatActivity {
final static int PICK_IMAGE_REQUEST = 1;
private String imageUriStr;
SharedPreferences prefs;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
prefs = this.getSharedPreferences("MyPreferences",MODE_PRIVATE);
ImageView addImgButton = (ImageView) findViewById(R.id.add_img_button);
addImgButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Select Picture"), PICK_IMAGE_REQUEST);
if (prefs.contains(imageUriStr)) {
imageUriStr = prefs.getString("imageUriStr", ""); //Get the data from prefs
}
Log.d("Value",imageUriStr); //verify if it is correct
prefs.edit().clear();
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
imageUriStr = data.getData().toString(); //convert to string to use it with SharedPreferences
prefs.edit().putString("imageUriStr",imageUriStr).apply();
}
}
}
一个解决办法是做onActivityresult里面的一切,但我也希望以后用户的另一个意图基于该URI来裁剪图像,但我认为一个onActivityresult内的意图将是太乱或它可以接受?我想我错过了一些东西。
我的代码保持会产生这种
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.prototypeapp, PID: 17826
java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.d(Log.java:154)
at com.example.android.prototypeapp.MainActivity$1$override.onClick(MainActivity.java:41)
at com.example.android.prototypeapp.MainActivity$1$override.access$dispatch(MainActivity.java)
at com.example.android.prototypeapp.MainActivity$1.onClick(MainActivity.java:0)
at android.view.View.performClick(View.java:5264)
at android.view.View$PerformClick.run(View.java:21297)
at android.os.Handler.handleCallback(Handler.java:743)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:5546)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)
你'imageUriStr'在'Log.d( “值”,imageUriStr);'是空 – SripadRaj
如果(prefs.contains( imageUriStr))更改为if(prefs.contains(“imageUriStr”))并添加Log.d里面如果 – comeback4you
感谢您的工作!所以它是这样工作的吗?:在你调用startActivityForResult之后,后面的代码仍然会在后台运行,并且在它返回之后,它将在startActivityForResult之后从行中拾取。 –