问题：
有没有办法删除此nullobject引用错误？我正在尝试从扫描仪活动打开底部对话框
邰胤
>
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.swiftpass, PID: 16875
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.example.swiftpass.ScanPopUpDialog.setPrompt(ScanPopUpDialog.java:47)
at com.example.swiftpass.ScanQrActivity$MyImageAnalyzer.readerBarcodeData(ScanQrActivity.java:170)
at com.example.swiftpass.ScanQrActivity$MyImageAnalyzer.access$200(ScanQrActivity.java:109)
at com.example.swiftpass.ScanQrActivity$MyImageAnalyzer$3.onSuccess(ScanQrActivity.java:142)
at com.example.swiftpass.ScanQrActivity$MyImageAnalyzer$3.onSuccess(ScanQrActivity.java:138)
at com.google.android.gms.tasks.zzn.run(com.google.android.gms:play-services-tasks@@17.2.0:4)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6944)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)
XML代码：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/img_close"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:src="@drawable/ic_close">
</ImageView>
<TextView
android:id="@+id/txt_type"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="6dp"
android:text="@string/qr_type"
android:fontFamily="@font/roboto_black"
android:textSize="20dp">
</TextView>
<TextView
android:id="@+id/txt_prompt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="50dp"
android:layout_marginBottom="10dp"
android:text="@string/qr_prompt"
android:fontFamily="@font/roboto_medium"
android:textSize="18dp">
</TextView>
</RelativeLayout>
</LinearLayout>
底部对话框java：
包装com.example.swiftpass；
导入android。操作系统。捆导入android。看法拉平机；导入android。看法看法导入android。看法视图组；导入android。小装置。图像视图；导入android。小装置。文本视图；导入androidx。注释。非空；导入androidx。注释。可为空；
导入com.google.Android布料底片。底部碎片；
公共类ScanPopDialog扩展了BottomSheetDialogFragment{
//Declaration of Variables
TextView type;
TextView prompt;
ImageView close;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.pop_up_dialog, container, false);
type = view.findViewById(R.id.txt_type);
prompt = view.findViewById(R.id.txt_prompt);
close = view.findViewById(R.id.img_close);
close.setOnClickListener(this::OnClick);
return view;
}
//This function will listen to button clicks and will call certain functions according to what is pressed by the user
private void OnClick(View view) {
switch(view.getId()){
case R.id.img_close:
dismiss();
break;
case R.id.txt_prompt:
break;
}
}
public void setPrompt(String type, String prompt){
this.type.setText(type);
this.prompt.setText(prompt);
if (type == "TEXT"){
this.prompt.setOnClickListener(this::OnClick);
}
}
}
扫描仪活动java：
包装com.example.swiftpass；
导入androidx。注释。非空；导入androidx。appcompat。应用程序。应用程序活动；导入androidx。照相机果心摄影师；导入androidx。照相机果心图像分析；导入androidx。照相机果心图像采集；导入androidx。照相机果心图像代理；导入androidx。照相机果心预览导入androidx。照相机生命周期。过程摄像机提供器；导入androidx。照相机看法预览视图；导入androidx。果心应用程序。活动公司；导入androidx。果心所容纳之物语境相容；导入androidx。碎片应用程序。碎片管理器；
导入android。显示导入android。注释。抑制皮棉；导入android。所容纳之物下午。包装经理；导入android。图样指向导入android。图样直肠；导入android。媒体形象导入android。操作系统。捆导入android。util。大小导入android。小装置。干杯
导入com.google.Androidgms。任务。OnCompleteListener；导入com.google.Androidgms。任务。失败的听众；导入com.google.Androidgms。任务。OnSuccessListener；导入com.google.Androidgms。任务。任务导入com.google.常见的util。同时发生的可听未来；导入com.google.mlkit。视力条形码。条形码；导入com.google.mlkit。视力条形码。条形码扫描仪；导入com.google.mlkit。视力条形码。条码扫描选项；导入com.google.mlkit。视力条形码。条码扫描；导入com.google.mlkit。视力常见的输入图像；
导入java.util.列表；导入java.util.concurrent.执行例外；导入java.util.concurrent.执行服务；导入java.util.concurrent.执行人；
公共类ScanQrActivity扩展了AppCompatActivity{
//Declaration of Variables
private ListenableFuture cameraProviderFuture;
private ExecutorService cameraExecutor;
private PreviewView previewView;
private MyImageAnalyzer analyzer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan_qr);
//Assigning of widgets and Setting up of listeners
initializeScan();
cameraProviderFuture.addListener(new Runnable() {
@Override
public void run() {
try {
if (ActivityCompat.checkSelfPermission(ScanQrActivity.this, Manifest.permission.CAMERA) != (PackageManager.PERMISSION_GRANTED)){
ActivityCompat.requestPermissions(ScanQrActivity.this, new String [] {Manifest.permission.CAMERA}, 101);
}else{
ProcessCameraProvider processCameraProvider = (ProcessCameraProvider) cameraProviderFuture.get();
bindPreview(processCameraProvider);
}
}catch (ExecutionException e){
e.printStackTrace();
}catch (InterruptedException e){
e.printStackTrace();
}
}
}, ContextCompat.getMainExecutor(this));
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 101 && grantResults.length > 0){
ProcessCameraProvider processCameraProvider = null;
try {
processCameraProvider = (ProcessCameraProvider) cameraProviderFuture.get();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
bindPreview(processCameraProvider);
}
}
private void bindPreview(ProcessCameraProvider processCameraProvider) {
Preview preview = new Preview.Builder().build();
CameraSelector cameraSelector = new CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
preview.setSurfaceProvider(previewView.getSurfaceProvider());
ImageCapture imageCapture = new ImageCapture.Builder().build();
ImageAnalysis imageAnalysis = new ImageAnalysis.Builder()
.setTargetResolution(new Size(1280, 720))
.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
.build();
imageAnalysis.setAnalyzer(cameraExecutor, analyzer);
processCameraProvider.unbindAll();
processCameraProvider.bindToLifecycle(this,cameraSelector, preview, imageCapture, imageAnalysis);
}
public class MyImageAnalyzer implements ImageAnalysis.Analyzer{
private FragmentManager fragmentManager;
private ScanPopUpDialog bottomDialog;
public MyImageAnalyzer(FragmentManager fragmentManager){
this.fragmentManager = fragmentManager;
bottomDialog = new ScanPopUpDialog();
}
@Override
public void analyze(@NonNull ImageProxy imageProxy) {
scanBarcode(imageProxy);
}
private void scanBarcode(ImageProxy imageProxy) {
BarcodeScannerOptions options =
new BarcodeScannerOptions.Builder()
.setBarcodeFormats(
Barcode.FORMAT_QR_CODE)
.build();
@SuppressLint("UnsafeExperimentalUsageError") Image mediaImage = imageProxy.getImage();
assert mediaImage != null;
InputImage inputImage =
InputImage.fromMediaImage(mediaImage, imageProxy.getImageInfo().getRotationDegrees());
BarcodeScanner scanner = BarcodeScanning.getClient(options);
Task<List<Barcode>> result = scanner.process(inputImage)
.addOnSuccessListener(new OnSuccessListener<List<Barcode>>() {
@Override
public void onSuccess(List<Barcode> barcodes) {
// Task completed successfully
readerBarcodeData(barcodes);
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
// Task failed with an exception
// ...
e.printStackTrace();
}
})
.addOnCompleteListener(new OnCompleteListener<List<Barcode>>() {
@Override
public void onComplete(@NonNull Task<List<Barcode>> task) {
imageProxy.close();
}
});
}
private void readerBarcodeData(List<Barcode> barcodes) {
for (Barcode barcode: barcodes) {
Rect bounds = barcode.getBoundingBox();
Point[] corners = barcode.getCornerPoints();
String rawValue = barcode.getRawValue();
int valueType = barcode.getValueType();
switch (valueType){
case Barcode.TYPE_TEXT:
bottomDialog.setPrompt(rawValue, "CLICK TO CONFIRM");
break;
case Barcode.TYPE_CALENDAR_EVENT:
bottomDialog.setPrompt("Calendar Event", "Unsupported Type");
break;
case Barcode.TYPE_CONTACT_INFO:
bottomDialog.setPrompt("Contact Info", "Unsupported Type");
break;
case Barcode.TYPE_DRIVER_LICENSE:
bottomDialog.setPrompt("Driver's License", "Unsupported Type");
break;
case Barcode.TYPE_EMAIL:
bottomDialog.setPrompt("E-mail", "Unsupported Type");
break;
case Barcode.TYPE_GEO:
bottomDialog.setPrompt("Location", "Unsupported Type");
break;
case Barcode.TYPE_ISBN:
bottomDialog.setPrompt("Book Number", "Unsupported Type");
break;
case Barcode.TYPE_PHONE:
bottomDialog.setPrompt("Phone", "Unsupported Type");
break;
case Barcode.TYPE_PRODUCT:
bottomDialog.setPrompt("Product", "Unsupported Type");
break;
case Barcode.TYPE_SMS:
bottomDialog.setPrompt("SMS", "Unsupported Type");
break;
case Barcode.TYPE_URL:
bottomDialog.setPrompt("Link", "Unsupported Type");
break;
case Barcode.TYPE_WIFI:
bottomDialog.setPrompt("Wi-Fi", "Unsupported Type");
break;
default:
bottomDialog.setPrompt("Uknown", "Uknown Type");
}
if (!bottomDialog.isAdded()){
bottomDialog.show(fragmentManager, "");
}
}
}
}
private void initializeScan() {
previewView = findViewById(R.id.previewView);
this.getWindow().setFlags(1024,1024);
cameraExecutor = Executors.newSingleThreadExecutor();
cameraProviderFuture = ProcessCameraProvider.getInstance(this);
analyzer = new MyImageAnalyzer(getSupportFragmentManager());
}
}
共有1个答案
柴彬
我解决了它，代码如下：
package com.example.swiftpass;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.google.android.material.bottomsheet.BottomSheetDialogFragment;
public class ScanPopUpDialog extends BottomSheetDialogFragment {
//Declaration of Variables
TextView type;
TextView prompt;
ImageView close;
String stringType;
String stringPrompt;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.pop_up_dialog, container, false);
type = view.findViewById(R.id.txt_type);
type.setText(getStringType());
prompt = view.findViewById(R.id.txt_prompt);
prompt.setText(getStringPrompt());
if (stringPrompt == "CLICK TO CONFIRM"){
prompt.setOnClickListener(this::OnClick);
}
close = view.findViewById(R.id.img_close);
close.setOnClickListener(this::OnClick);
return view;
}
//This function will listen to button clicks and will call certain functions according to what is pressed by the user
private void OnClick(View view) {
switch(view.getId()){
case R.id.img_close:
dismiss();
break;
case R.id.txt_prompt:
break;
}
}
public void setDialog(String type, String prompt){
/**
* This method is public because it is being called fron the scan qr activity
* this will set the value for the objects stringType and stringPrompt
* this does not return any value thus, the values will be accessed through
* get method
*/
stringType = type;
stringPrompt = prompt;
}
/**
*These methods are used to access the value set by the setDialog method
*
*/
private String getStringType(){
return stringType;
}
private String getStringPrompt(){
return stringPrompt;
}
}
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