从另一个类中的类调用 startActivityForResult() 时出现问题(空指针异常)，代码如下:
public class OCRActivity extends Activity {
public OCRActivity(String operator)
{
this.operator = operator;
}
public void startCameraActivity() {
final Intent capture_intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(capture_intent, 1); // I get the Null pointer Exception here
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if(requestCode == 1){
//get the Uri for the captured image
picUri = data.getData();
//carry out the crop operation
performCrop();
}
}
这里是我调用 startCameraActivity() 的地方
public class WayToFillActivity extends Activity implements OnClickListener {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.way_to_fill);
CAMERA_BTN = (Button) findViewById(R.id.camera_btn);
CAMERA_BTN.setOnClickListener(this);
Intent operator_intent = getIntent();
OPERATOR = operator_intent.getStringExtra("operator");
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.camera_btn)
{
OCRActivity ocr = new OCRActivity(OPERATOR);
ocr.startCameraActivity();
}
}
所以如果我做错了什么请告诉我!!
逻辑猫
01-13 16:22:26.583: E/AndroidRuntime(32425): java.lang.NullPointerException
01-13 16:22:26.583: E/AndroidRuntime(32425): at android.app.Activity.startActivityForResult(Activity.java:3190)
01-13 16:22:26.583: E/AndroidRuntime(32425): at com.almannaa.EasyRecharge.OCRActivity.startCameraActivity(OCRActivity.java:176)
最佳答案
您将 OCRActivity 视为一个普通的 Java 类，而不是另一个 Activity。因此，当您调用 startActivityForResult() 时，您会得到一个 NPE，因为 Activity 的 onCreate() 尚未被调用，这意味着它的当前实例对于调用无效startActivityForResult()
相反，请尝试使用:
public class WayToFillActivity extends Activity implements OnClickListener {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.way_to_fill);
CAMERA_BTN = (Button) findViewById(R.id.camera_btn);
CAMERA_BTN.setOnClickListener(this);
Intent operator_intent = getIntent();
OPERATOR = operator_intent.getStringExtra("operator");
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.camera_btn)
{
OCRActivity ocr = new OCRActivity(OPERATOR);
ocr.startCameraActivity();
}
}
public void startCameraActivity() {
final Intent capture_intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(capture_intent, 1); // I get the Null pointer Exception here
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if(requestCode == 1){
//get the Uri for the captured image
picUri = data.getData();
//carry out the crop operation
performCrop();
}
}
}
您可能应该将像 performCrop() 这样的函数(以及任何其他实际上不需要在 Activity 本身中，并且可以通过接收数据作为参数并返回它来工作的函数)移动到一个单独的类(称其为 Utility 或其他)。
关于android - 调用 startActivityForResult() 时出现空指针异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14306094/