为什么我的 Android 对话框会抛出 NullPointer？
[英]Why does my Android Dialog throw a NullPointer?
问题描述
i've been struggling with a simple Android Dialog that I need in order to add elements to a list;
我一直在努力使用一个简单的 Android 对话框，以便将元素添加到列表中； it's pretty simple (an edit text, a spinner and a button), but when I try to show it it just keeps throwing a NullPointerException.它非常简单（一个编辑文本、一个微调器和一个按钮），但是当我尝试显示它时，它只是不断抛出 NullPointerException。 May I have your help with this matter?我可以在这件事上得到你的帮助吗？
The error:错误：
E/AndroidRuntime: FATAL EXCEPTION: main Process: rmr.kairos, PID: 4519 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:454) at android.widget.ArrayAdapter.getView(ArrayAdapter.java:416) at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:206) at android.widget.Spinner.onMeasure(Spinner.java:614) at androidx.appcompat.widget.AppCompatSpinner.onMeasure(AppCompatSpinner.java:438) at android.view.View.measure(View.java:25466) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552) at android.widget.LinearLayout.measureVertical(LinearLayout.java:842) at android.widget.LinearLayout.onMeasure(LinearLayout.java:721) at android.view.View.measure(View.java:25466) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957) at and
The Activity ( @TylerV, I've tried to set an adapter and it does the same, what am I doing wrong?):活动（@TylerV，我试图设置一个适配器，它也一样，我做错了什么？）：
public class TagActivity extends AppCompatActivity {
private ListView lvTag;
private ImageView imBack;
private ImageView imNewTag;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tag);
lvTag = findViewById(R.id.lvTags);
imBack = findViewById(R.id.imBack);
imNewTag = findViewById(R.id.imNewTag);
imBack.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intentToMain = new Intent(getApplicationContext(), rmr.kairos.activities.MainActivity.class);
startActivity(intentToMain);
finish();
}
});
imNewTag.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showTagDialog();
}
});
newTagList(lvTag);
}
public TagAdapter newTagList(ListView lvTag){
ArrayList<Tag> listaEtiquetas = new ArrayList<Tag>();
//introducir los valores con un diaálogo o algo
listaEtiquetas.add(new Tag("prueba", "#FFFFFF"));
TagAdapter tagAdapter = new TagAdapter(this, R.layout.layout_tag, listaEtiquetas);
lvTag.setAdapter(tagAdapter);
return tagAdapter;
}
public void showTagDialog(){
AlertDialog.Builder tagBuilder = new AlertDialog.Builder(TagActivity.this);
View tagView = getLayoutInflater().inflate(R.layout.dialog_tag,null);
EditText etTagName = tagView.findViewById(R.id.etTagName);
Spinner spTagColor = tagView.findViewById(R.id.spTagColor);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(TagActivity.this,
android.R.layout.simple_spinner_item,
getResources().getStringArray(R.array.tagSpinnerArray));
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spTagColor.setAdapter(adapter);
tagBuilder.setPositiveButton("Aceptar", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
if (!spTagColor.getSelectedItem().toString().equalsIgnoreCase("Seleccione un color")){
Toast.makeText(TagActivity.this, spTagColor.getSelectedItem().toString()
, Toast.LENGTH_SHORT).show();
dialogInterface.dismiss();
}
}
});
tagBuilder.setCancelable(true);
tagBuilder.setView(tagView);
AlertDialog dialog = tagBuilder.create();
dialog.show();
}
}
The Dialog XML:对话框 XML：
<?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="wrap_content"
android:layout_margin="10dp"
android:orientation="vertical"
android:weightSum="10">
<TextView
android:id="@+id/tvDialogTag"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:layout_weight="5"
android:fontFamily="@font/simplifica"
android:text="@string/strDialogTag"
android:textAlignment="center"
android:textSize="24sp"
android:textStyle="bold" />
<EditText
android:id="@+id/etTagName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="@font/simplifica"
android:hint="@string/strTagTitle"
android:shadowColor="#FFFFFF"
android:textColor="#FFFFFF"
android:textSize="24sp"
android:textStyle="bold" />
<Spinner
android:id="@+id/spTagColor"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:layout_weight="5"
android:entries="@array/tagSpinnerArray" />
<Button
android:id="@+id/btDialogTag"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:layout_weight="5"
android:text="@string/submit" />
</LinearLayout>
1 个解决方案
解决方案1
0 已采纳 2022-06-15 20:10:08
Sadly I couldn't find a solution and my time was running out, so I simply used a radioGroup;遗憾的是我找不到解决方案，而且我的时间不多了，所以我只使用了一个 radioGroup； not the fanciest of the solutions, but a solution.不是最花哨的解决方案，而是一个解决方案。 Thanks everyone!!感谢大家！！
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.