所以我按照Android开发者网站上的当前指南（http://developer.android.com/guide/topics/ui/dialogs.html#CustomLayout）创建了一个自定义对话框，并希望将用户输入从EditText传回MainActivity;但事实证明MainActivity收到null。我不明白为什么。
非常感谢任何帮助。
这是我的代码：
MainActivity.java
public class MainActivity extends AppCompatActivity implements NewItemFragment.NoticeDialogListener {
private final static String TAG = "tag";
RecyclerView recyclerView;
RecyclerView.LayoutManager manager;
RecyclerView.Adapter adapter;
FloatingActionButton fab;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
NewItemFragment dialog = new NewItemFragment();
dialog.show(getSupportFragmentManager(), "newitem");
}
});
manager = new LinearLayoutManager(this);
recyclerView = (RecyclerView) findViewById(R.id.recycler);
recyclerView.setLayoutManager(manager);
initialiseData();
initialiseAdapter();
}
@Override
public void onDialogPositiveClick(DialogFragment dialogFragment) {
LayoutInflater inflater = getLayoutInflater();
View view = inflater.inflate(R.layout.new_item_dialog, null);
EditText editText = (EditText) view.findViewById(R.id.newitem);
String input = editText.getText().toString();
EditText result = (EditText) findViewById(R.id.textedit);
int i = entries.size();
if (input.equals("")) {
result.setText("Fail");
} else {
entries.add(new Items(input));
adapter.notifyItemInserted(i + 1);
}
}
@Override
public void onDialogNegativeClick(DialogFragment dialogFragment) {
}
}
NewItemFragment.java
public class NewItemFragment extends DialogFragment {
public interface NoticeDialogListener {
public void onDialogPositiveClick(DialogFragment dialogFragment);
public void onDialogNegativeClick(DialogFragment dialogFragment);
}
NoticeDialogListener listener;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
listener = (NoticeDialogListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement NoticeDialogListener");
}
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
final LayoutInflater inflater = getActivity().getLayoutInflater();
final View view = inflater.inflate(R.layout.new_item_dialog, null);
builder.setView(view)
.setPositiveButton(R.string.add, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
listener.onDialogPositiveClick(NewItemFragment.this);
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
NewItemFragment.this.getDialog().cancel();
}
});
return builder.create();
}
}
最后是new_item_dialog.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingTop="24dp"
android:paddingStart="24dp"
android:paddingEnd="24dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="24sp"
android:textColor="#000000"
android:text="@string/new_item"
android:layout_marginBottom="20dp"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/newitem"
android:hint="@string/hint"
android:layout_marginBottom="24dp"/>
</LinearLayout>
谢谢， 约什
答案 0 :(得分：0)
我会以这种方式更改EditText，因为您只需要public interface NoticeDialogListener {
public void onDialogPositiveClick(final String input);
public void onDialogNegativeClick();
}
的内容
setPositiveButton并且在调用.setPositiveButton(R.string.add, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
listener.onDialogPositiveClick( ((TextVew)view.findViewById(R.id.newitem)).getText().toStrig());
}
时
.data
Prompt1: .asciiz"\nPlease enter the first string. "
Prompt2: .asciiz"\nPlease enter the second string. "
theString: .asciiz"\nYou typed: \n"
equalPrompt: .asciiz"\nThe strings are equal\n"
notEqualPrompt: .asciiz"\nThe strings are not equal\n"
stringLengthPrompt: .asciiz"\nThe string length is: \n"
stringAppend: .asciiz"\nThe appended strings are: "
stringAppend2: .asciiz" "
stringOne: .space 100
stringTwo: .space 100
.text
main:
li $t0,0
jal getStrings
la $s4,stringOne
jal stringLength
move $s0,$t0 #copy string one length
la $s4,stringTwo
jal stringLength
move $s1,$t0 #copy string two length
la $t5,stringOne
la $t6,stringTwo
jal testEquality
la $t5,stringOne
lb $t1, 0($t5)
jal append1
la $t6,stringTwo
lb $t1, 0($t6)
jal append2
j end
getStrings:
li $v0,4
la $a0, Prompt1
syscall
li $v0,8
la $a0, stringOne
li $a1, 40
syscall
#string one has been read in
li $v0,4
la $a0, Prompt2
syscall
li $v0,8
la $a0, stringTwo
li $a1, 40
syscall
#string two has been read in
la $a0,theString # "you typed:"
li $v0,4
syscall
la $a0,stringOne
li $v0,4
syscall
la $a0,stringTwo
li $v0,4
syscall
jr $ra
end:
li $v0,10
syscall
stringLength: #calculate length of strings to allocate memory
li $t0,0
stringLength1:
lb $t1, 0($s4)
beqz $t1,out
addi $s4,$s4, 1 #move position
addi $t0,$t0, 1 #counter
j stringLength1
out:
la $a0,stringLengthPrompt
li $v0,4
syscall
move $a0, $t0 #length of string
li $v0,1
syscall
jr $ra
equal:
la $a0, equalPrompt
li $v0,4
syscall
jr $ra
notEqual:
la $a0, notEqualPrompt
li $v0,4
syscall
jr $ra
testEquality: #test if both strings are equal
lb $t1, 0($t5)
lb $t2, 0($t6)
bne $t1,$t2, notEqual
addi $t5,$t5,1
addi $t6,$t6,1
add $t7,$t1,$t2
beqz $t7,equal
j testEquality
append1:
add $s2,$s0,$s1
move $a0,$s2
li $v0,9
syscall
move $t8,$v0
move $t9,$v0
append2:
beqz $t1,append3
sb $t1,0($t8)
addi $t5,$t5,1
addi $t8,$t8,1
lb $t1, 0($t5)
b append2
append3:
beqz $t1,appendOut
sb $t1,0($t9)
addi $t6,$t6,1
addi $t9,$t9,1
lb $t1, 0($t6)
b append3
appendOut:
li $v0,4
la $a0, stringAppend
syscall
move $a0, $t9
li $v0,4
syscall
jr $ra