如何在AlertDialog中读取RadioGroup的值？

Question

所以我使用AlertDialog来显示我的RadioGroup，我希望将RadioButton的值传递给我的下一个方法。但是，当我运行该程序时，它返回一个错误：

java.lang.NullPointerException：尝试在空对象引用上调用虚方法'int android.widget.RadioGroup.getCheckedRadioButtonId（）'

我该如何解决 ？

private void showChoosePackage() {

    AlertDialog.Builder builder = new AlertDialog.Builder(descriptionsActivity.this);
    LayoutInflater inflater = this.getLayoutInflater();
    View choose_package_layout = inflater.inflate(R.layout.choose_package_layout, null);

    builder.setView(choose_package_layout);
    final  AlertDialog dialog = builder.create();

    radioGroup = findViewById(R.id.radio_grp);
    Button btnApply = choose_package_layout.findViewById(R.id.button_apply);

    final RadioButton rdibtn = (RadioButton)choose_package_layout.findViewById(R.id.radio1);
    final RadioButton rdibtn2 = (RadioButton)choose_package_layout.findViewById(R.id.radio2);

    rdibtn.setText(Common.longhousedesc.PackageOne);
    rdibtn2.setText(Common.longhousedesc.PackageTwo);

    btnApply.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            int Selectedid = radioGroup.getCheckedRadioButtonId();
            radioButton = findViewById(Selectedid);

            showConfirmDialog(radioButton.getText());
        }
    });

    builder.show();

}

Answer 1

您需要在查找无线电组时指定视图：

radioGroup = choose_package_layout.findViewById(R.id.radio_grp);

Answer 2

findViewById需要一个上下文来查找视图。由于您在对话框中调用它，因此需要在其视图中查找该视图。

private void showChoosePackage() {

    AlertDialog.Builder builder = new AlertDialog.Builder(descriptionsActivity.this);
    LayoutInflater inflater = this.getLayoutInflater();
    final View choose_package_layout = inflater.inflate(R.layout.choose_package_layout, null);

    builder.setView(choose_package_layout);
    final  AlertDialog dialog = builder.create();

    final RadioGroup radioGroup = findViewById(R.id.radio_grp);
    Button btnApply = choose_package_layout.findViewById(R.id.button_apply);

    final RadioButton rdibtn = (RadioButton)choose_package_layout.findViewById(R.id.radio1);
    final RadioButton rdibtn2 = (RadioButton)choose_package_layout.findViewById(R.id.radio2);

    rdibtn.setText(Common.longhousedesc.PackageOne);
    rdibtn2.setText(Common.longhousedesc.PackageTwo);

    btnApply.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            int Selectedid = radioGroup.getCheckedRadioButtonId();
            radioButton = choose_package_layout.findViewById(Selectedid);

            showConfirmDialog(radioButton.getText());
        }
    });



    dialog.show();

     }