Android 为什么我的自定义警报对话框代码崩溃？

我正在尝试将自定义视图应用于警报对话框。我是这样做的，但是当我试图显示警报框时，会出现nullpointer异常

我创建一个layout.xml，如下所示：

<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"  
  android:id="@+id/themescreen"
  android:gravity="center"
  android:orientation="horizontal"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
 >
<TableLayout
android:padding="45dip"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<RadioGroup
android:gravity="center">
<TableRow>
<RadioButton
android:id="@+id/rdthemeBlue"
android:button="@drawable/radio_custom">
</RadioButton>
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:src="@drawable/bluebackgroundicon"
android:paddingLeft="10dip"
android:paddingBottom="10dip"
></ImageView>
</TableRow>
<TableRow>
<RadioButton
android:id="@+id/rdthemeGolden"
android:button="@drawable/radio_custom"></RadioButton>
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:src="@drawable/goldenredbackgroundicon"
android:paddingLeft="10dip"
android:paddingBottom="10dip"
></ImageView>
</TableRow>

<TableRow>
<RadioButton
android:id="@+id/rdthemeBlack"
android:button="@drawable/radio_custom">
</RadioButton>
<TextView
android:gravity="center"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dip"
android:text="None"
>
</TextView>
</TableRow>
</RadioGroup>
<TableRow
android:paddingTop="25dip"
android:paddingLeft="10dip"
>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
>
<Button
android:id="@+id/btnthemesave"
android:background="@drawable/btn_custom"
android:layout_width="100dip"
android:layout_height="wrap_content"
android:paddingLeft="10dip"
android:text="Save"
android:textSize="15sp"
 ></Button>
<Button
android:id="@+id/btnthemecancel"
android:background="@drawable/btn_custom"
android:layout_width="100dip"
android:layout_height="wrap_content"
android:paddingLeft="10dip"
android:text="Cancel"
android:textSize="15sp"
></Button>
</LinearLayout>
</TableRow>
</TableLayout>
</LinearLayout>

什么可能导致空指针异常

public class BranchDialog extends android.app.Dialog
{

    ListView list;
    Context context;
    TextView title; 
    ProgressBar progress;

    public BranchDialog(Context context, String rid, String name) 
    {
        super(context);

        setContentView(R.layout.branch_dialog);
        setCancelable(true);
        setTitle(name);
        this.context = context;

        title = (TextView)findViewById(R.id.branch_dialog_title);

        title.setText("this is my custom title");
        show();
    }

}

---

稍作更改后，可能对您有帮助。

请尝试使用这些代码创建警报对话框，它对我有用

AlertDialog.Builder alert;
alert = new AlertDialog.Builder(Deal_Purchase_Checkout.this);
alert.setTitle("Enter Your Title");
alert.setView(input);
alert.setPositiveButton("Ok",new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog,int whichButton){
    //Some Code
 }
});
alert.setNegativeButton("Cancel",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int whichButton) {
        dialog.cancel();
    }
});
alert.show();

AlertDialog.Builder alert;
alert = new AlertDialog.Builder(Deal_Purchase_Checkout.this);
alert.setTitle("Enter Your Title");
alert.setView(input);
alert.setPositiveButton("Ok",new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog,int whichButton){
    //Some Code
 }
});
alert.setNegativeButton("Cancel",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int whichButton) {
        dialog.cancel();
    }
});
alert.show();