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[英]How to save and retrieve an arraylist of strings with the same order, using shared preferences
[英]How to save/retrieve a bitmap's file path using Shared Preferences
因此,伙计们,我正在尝试通过SharedPreferences保存位图图像的路径,如果用户之前已经在应用程序上拍摄过照片,则必须在“ onCreate”上进行检索
这是打开的摄像头和onActivityResult代码
public void abrirCamera(View v){
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
cameraIntent.putExtra("android.intent.extras.CAMERA_FACING", 1);
startActivityForResult(cameraIntent, RESULT_FIRST_USER);
}
public Uri getImageUri(Context inContext, Bitmap inImage) {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
inImage.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
String path = MediaStore.Images.Media.insertImage(inContext.getContentResolver(), inImage, "Title", null);
return Uri.parse(path);
}
public String getRealPathFromURI(Uri uri) {
Cursor cursor = getContentResolver().query(uri, null, null, null, null);
cursor.moveToFirst();
int idx = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
return cursor.getString(idx);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == RESULT_FIRST_USER){
Bitmap image = (Bitmap) data.getExtras().get("data");
imageView.setImageBitmap(image);
// CALL THIS METHOD TO GET THE URI FROM THE BITMAP
Uri tempUri = getImageUri(getApplicationContext(), image);
// CALL THIS METHOD TO GET THE ACTUAL PATH
File finalFile = new File(getRealPathFromURI(tempUri));
outputFileUri = Uri.fromFile(finalFile);
stringUri = outputFileUri.toString();
editor.putString("imagepath", stringUri);
editor.commit();
}
}
这是onCreate:
public class MainActivity extends AppCompatActivity {
public static final String PREFS_NAME = "MyPref";
EditText editWeight;
EditText editHeight;
RatingBar rb1;
SharedPreferences prefs;
SharedPreferences.Editor editor;
float i;
Uri outputFileUri;
Uri uriString;
String stringUri;
ImageView imageView;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editWeight = (EditText) findViewById(R.id.editWeight);
editHeight = (EditText) findViewById(R.id.editHeight);
imageView = (ImageView) findViewById(R.id.imageView1);
rb1 = (RatingBar) findViewById(R.id.rb1);
prefs = getApplicationContext().getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
String restoredText = prefs.getString("text", "");
if (restoredText.equals("")){
float peso = prefs.getFloat("peso", 0);
float altura = prefs.getFloat("altura", 0);
editWeight.setText(String.valueOf(peso));
editHeight.setText(String.valueOf(altura));
float rating = prefs.getFloat("rating", 0);
rb1.setRating(Float.parseFloat(String.valueOf(rating)));
String imagepath = prefs.getString("imagepath", "");
uriString = Uri.parse(imagepath);
imageView.setImageURI(uriString);
}
}
我试图通过String发送到我的sharedPreferences,然后在ononCreate上将String转换为Uri,因此可以在ImageView上设置图像。
这是错误:
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { act=inline-data dat=content://media/external/images/media/5047 (has extras) }} to activity {com.example.casa.myimc/com.example.casa.myimc.MainActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'android.content.SharedPreferences$Editor android.content.SharedPreferences$Editor.putString(java.lang.String, java.lang.String)' on a null object reference
造成原因:
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'android.content.SharedPreferences$Editor android.content.SharedPreferences$Editor.putString(java.lang.String, java.lang.String)' on a null object reference
您尚未初始化editor
,因此出错。 初始化prefs
后,必须在onCreate
方法中对其进行初始化
prefs = getApplicationContext().getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
editor = prefs.edit();
像这样。
还要在stackoverflow上检查what is NullPointerException in java
。 您将获得详细信息。
希望对您有所帮助。
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