空对象引用上的自定义对话框错误“android.text.Editable android.widget.EditText.getText()”

Question

我创建了一个显示项目网格的自定义对话框。单击另一个选项时，它还将打开另一个带有 editText 字段的自定义对话框。我面临的问题是文本字段出现空对象错误。我找到了答案here，但是当我应用它时，结果还是一样。

基本上，在从另一个自定义对话框打开的自定义对话框中检索文本字段值时，应用程序会崩溃。这是我目前所拥有的：

onCreate()

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button donate = findViewById(R.id.button);

    donate.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            showDonateDialog();
        }
    });
}

showDonateDialog()

//Donate dialog with grid options
private void showDonateDialog() {
    // Prepare grid view
    GridView gridView = new GridView(this);
    String[] donateAmount = getResources().getStringArray(R.array.donationAmount);

    List<String> donateList = new ArrayList<String>();
    Collections.addAll(donateList, donateAmount);

    gridView.setAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, donateList));
    gridView.setNumColumns(3);
    gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Toast.makeText(getApplicationContext(), "Thank you for your donation!", Toast.LENGTH_SHORT).show();
        }
    });

    // Set grid view to alertDialog
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setView(gridView);
    builder.setTitle("Donate");
    builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });
    builder.setNeutralButton("Other amount", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            showCustomDonate();
        }
    });
    builder.setCancelable(false);
    builder.show();
}

showCustomDonate()

//Donate dialog for custom amount
private void showCustomDonate() {
    AlertDialog.Builder builderCustom = new AlertDialog.Builder(this);
    Context context = builderCustom.getContext();
    LayoutInflater layoutInflater = LayoutInflater.from(context);
    View view = layoutInflater.inflate(R.layout.custom_donate_amount, null, false);

    final EditText donateAmount = findViewById(R.id.editAmount);
    final DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            if (which == DialogInterface.BUTTON_NEGATIVE) {
                dialog.cancel();
            } else {
            String amount = donateAmount.getText().toString(); //Error null object reference here
            Toast.makeText(getApplicationContext(), "Thank you for donating " + amount, Toast.LENGTH_LONG).show();
            }
        }
    };

    builderCustom.setView(view)
                .setTitle("Custom Donation")
                .setCancelable(false)
                .setPositiveButton("OK", listener)
                .setNegativeButton("CANCEL", listener)
                .show();

}

日志

    E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.customdialog, PID: 12011
java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
    at com.example.customdialog.MainActivity$5.onClick(MainActivity.java:94)
    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Answer 1

希望对你有用

showCustomDonate()

//Donate dialog for custom amount
private void showCustomDonate() {
    AlertDialog.Builder builderCustom = new AlertDialog.Builder(this);
    Context context = builderCustom.getContext();
    LayoutInflater layoutInflater = LayoutInflater.from(context);
    View view = layoutInflater.inflate(R.layout.custom_donate_amount, null, false);

    final EditText donateAmount = findViewById(R.id.editAmount);
    final DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            if (which == DialogInterface.BUTTON_NEGATIVE) {
                dialog.cancel();
            } else {
            String amount = donateAmount.getText().toString(); //Error null object reference here
            Toast.makeText(getApplicationContext(), "Thank you for donating " + amount, Toast.LENGTH_LONG).show();
            }
        }
    };

    builderCustom.setView(view)
                .setTitle("Custom Donation")
                .setCancelable(false)
                .setPositiveButton("OK", listener)
                .setNegativeButton("CANCEL", listener)
                .show();

}

在此行更改

final EditText donateAmount = view.findViewById(R.id.editAmount);