对话框中 Spinner 和 EditText 不为空时启用按钮

Posted 2023-05-07

【中文标题】对话框中 Spinner 和 EditText 不为空时启用按钮

【英文标题】：Enable Button when Spinner and EditText are not empty in Dialog

【发布时间】：2019-08-04 22:07:38

【问题描述】：

在我的 AlertDialog 中，我有一个 Spinner 和一个 EditText。如果

，我正在尝试禁用对话框的肯定按钮

在 Spinner 中选择的项目是“选择货币”（“选择货币”是我的数组中的第一个项目，并且 Spinner 设置为将字符串货币名称返回为“”）或 EditText 为空。

在下面的代码中，如果我在 Spinner 中选择项目之前在 EditText 中进行了输入，则肯定按钮将保持禁用状态。我不知道如何使这两者一起工作。

任何帮助将不胜感激。谢谢。

private void openDialog()
    LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
    View subView = inflater.inflate(R.layout.dialog_layout, null);
    final EditText subEditTextExchangeRate = subView.findViewById(R.id.textInputExchangeRate);
    final Spinner subSpinner = subView.findViewById(R.id.spinner);

    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.currency, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    subSpinner.setAdapter(adapter);
    subSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() 
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) 
            if(parent.getItemAtPosition(position).equals("Select currency"))
                currencyName = "";

            else 
                currencyName = parent.getItemAtPosition(position).toString();
            
        
        @Override
        public void onNothingSelected(AdapterView<?> parent) 

        
    );

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setView(subView);

    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() 
        @Override
        public void onClick(DialogInterface dialog, int which) 
            exchangeRate = subEditTextExchangeRate.getText().toString();
            st2 = exchangeRate;
        
    );

    builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() 
        @Override
        public void onClick(DialogInterface dialog, int which) 

        
    );


    final AlertDialog alertDialog = builder.create();
    alertDialog.show();

    alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(false);
    subEditTextExchangeRate.addTextChangedListener(new TextWatcher() 
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) 

        

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) 
            String exchangeRateInput = subEditTextExchangeRate.getText().toString();
            alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!exchangeRateInput.isEmpty() && !currencyName.isEmpty()); 
        //This is the logic that I am looking for but the method is watching only EditText

        @Override
        public void afterTextChanged(Editable s) 

        
    );

【参考方案1】：

请尝试以下代码，只进行一项更改，将下面的行放在 subSpinner.setOnItemSelectedListener 中，并请全局声明 alertDialog。

alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!exchangeRateInput.isEmpty() && !currencyName.isEmpty());

这是您的代码。

private void openDialog()
    LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
    View subView = inflater.inflate(R.layout.dialog_layout, null);
    final EditText subEditTextExchangeRate = subView.findViewById(R.id.textInputExchangeRate);
    final Spinner subSpinner = subView.findViewById(R.id.spinner);

    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.currency, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    subSpinner.setAdapter(adapter);
    subSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() 
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) 
            if(parent.getItemAtPosition(position).equals("Select currency"))
                currencyName = "";

            else 
                currencyName = parent.getItemAtPosition(position).toString();
            
            alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!exchangeRateInput.isEmpty() && !currencyName.isEmpty()); 
        
        @Override
        public void onNothingSelected(AdapterView<?> parent) 

        
    );

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setView(subView);

    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() 
        @Override
        public void onClick(DialogInterface dialog, int which) 
            exchangeRate = subEditTextExchangeRate.getText().toString();
            st2 = exchangeRate;
        
    );

    builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() 
        @Override
        public void onClick(DialogInterface dialog, int which) 

        
    );


    alertDialog = builder.create();
    alertDialog.show();

    alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(false);
    subEditTextExchangeRate.addTextChangedListener(new TextWatcher() 
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) 

        

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) 
            String exchangeRateInput = subEditTextExchangeRate.getText().toString();
            alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!exchangeRateInput.isEmpty() && !currencyName.isEmpty()); 
        //This is the logic that I am looking for but the method is watching only EditText

        @Override
        public void afterTextChanged(Editable s) 

        
    );

【讨论】：

不错的一个。坚持下去

alertDialog 在 onItemSelected 中不可用，如下所述！

请全局显示警报对话框。我已经编辑了我的答案。

感谢您的快速回复。我刚刚尝试了答案并遇到以下错误：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'boolean java.lang.String.isEmpty（）'错误在“alertDialog.getButton（AlertDialog .BUTTON_POSITIVE).setEnabled(!exchangeRateInput.isEmpty() && !currencyName.isEmpty());"在“currencyName = parent.getItemAtPosition(position).toString();”之后

已解决。我在一开始就声明了 exchangeRateInput = ""。感谢您的帮助！

【参考方案2】：

您应该调用微调器的按钮启用/禁用逻辑Spinner.onItemSelected。到目前为止，您只检查 EditText.onTextChanged 中的逻辑。

在Spinner 和EditText 上设置侦听器之前声明您的AlertDialog。 在Spinner.onItemSelected 中添加您的逻辑以启用或禁用按钮。 在EditText.onTextChanged 中添加您的逻辑以启用或禁用按钮。

【参考方案3】：

如果你改变你的代码，你可以让你的代码工作，

    Button button = dialog.getButton(AlertDialog.BUTTON_POSITIVE);
    button.setEnabled(false);
        subEditTextExchangeRate.addTextChangedListener(new TextWatcher() 
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) 

            

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) 
            if(s.length>0 && !TextUtils.isEmpty(currencyName ))
            button.setEnabled(true);
            // your logic
           else
            button.setEnabled(false);
            // your logic
            


            @Override
            public void afterTextChanged(Editable s) 

            
        );

->这将完成你的工作。