在活动A 中,我有一个用于展示活动B 的图片按钮。
活动A
中部分工作代码 public void addListenerOnButton() {
imageButton = (ImageButton) findViewById(R.id.imageButton);
imageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Global.img=null;
Intent i = new Intent(A.this, B.class);
startActivityForResult(i, PROJECT_REQUEST_CODE);
}
});
}
public void onActivityResult(int requestCode,int resultCode, Intent data)
{
if(requestCode==PROJECT_REQUEST_CODE) {
c= data.getStringExtra("text");
txt1.setText(c);
viewImage.setImageBitmap(Global.img);
}
else if (requestCode==CAMERA_REQUEST_CODE)
{
}
}
活动B
selectImage();
public void selectImage() {
final CharSequence[] options = { "Take Photo", "Choose from Gallery","Cancel" };
AlertDialog.Builder builder = new AlertDialog.Builder(ImageFitScreen.this);
builder.setTitle("Add Photo!");
builder.setItems(options, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int item) {
if (options[item].equals("Take Photo"))
{
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
File f = new File(android.os.Environment.getExternalStorageDirectory(), "temp.jpg");
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));
//pic = f;
startActivityForResult(intent, 1);
} else if (options[item].equals("Choose from Gallery"))
{
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, 2);
} else if (options[item].equals("Cancel")) {
dialog.dismiss();
finish();
}
}
});
builder.setOnKeyListener(new Dialog.OnKeyListener() {
@Override
public boolean onKey(DialogInterface dialog, int keyCode,
KeyEvent event) {
// TODO Auto-generated method stub
if (keyCode == KeyEvent.KEYCODE_BACK){
dialog.dismiss();
finish();
}
return true;
}
});
builder.show();
}
@Override
public void onBackPressed() {
Intent returnIntent = new Intent();
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
}
但是当我点击对话框中的cancel
时,应用程序崩溃了。我确定崩溃是因为
c= data.getStringExtra("text");
因为c
删除后没有崩溃。但我需要活动B中的“文本”返回A。
Ok
按钮
ok.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0)
{
Intent returnIntent=new Intent();
text=t.getText().toString();
returnIntent.putExtra("text", text);
setResult(Activity.RESULT_OK, returnIntent);
finish();
}
});
LogCat错误
11-04 13:17:19.321 18437-18437/com.example.project.project E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.project.project, PID: 18437
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=0, data=null} to activity {com.example.project.project/com.example.project.project.Project1}: java.lang.NullPointerException
at android.app.ActivityThread.deliverResults(ActivityThread.java:3681)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3724)
at android.app.ActivityThread.access$1400(ActivityThread.java:175)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1356)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5602)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.project.project.Project1.onActivityResult(Project1.java:98)
答案 0 :(得分:1)
首先,您实际上并没有设置" text"的值。但是当你取消时,Intent为null,因此你无法做到
data.getStringExtra("text")
你应该先检查一下:
if (data !=null && data.hasExtra("text")){
c= data.getStringExtra("text");
txt1.setText(c);
}
然后在你的onbackpressed你想要设置"文本"额外如此:
@Override
public void onBackPressed() {
Intent returnIntent = new Intent();
returnIntent.putExtra("text", YOUR_STRING_HERE);
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
}
也许你的对话取消(取决于你想要完成的事情)
} else if (options[item].equals("Cancel")) {
dialog.dismiss();
Intent returnIntent = new Intent();
returnIntent.putExtra("text", YOUR_STRING_HERE);
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
}
答案 1 :(得分:1)
您没有通过意图向text
发送任何Activity A
字段。
在text
onBackPressed()
中设置Activity B
@Override
public void onBackPressed() {
Intent returnIntent = new Intent();
// Set the text here
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
}
喜欢
@Override
public void onBackPressed() {
Intent returnIntent = new Intent();
returnIntent.putExtra("text", YOUR_TEXT);
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
}