Question

我是android studio的新手，并创建了一个带有页面的应用程序，该页面可以选择2个微调器，用户输入一个时间然后结束时间＆＃39;计算。我正在尝试为此页面添加一些验证，因为当我点击“验证按钮”时应用程序崩溃，因为没有选择任何字段。我的意图是当用户选择“验证按钮”时。显示错误消息以确保填充微调器值，这意味着应用程序不会崩溃。我在onNothingSelected中尝试了一些方法，但它似乎没有用。我不确定它是否需要在那里或VerifyButton？提前谢谢！

Spinner Java

final ArrayAdapter<String> myAdapter = new ArrayAdapter<String>(CreateLine.this,
            R.layout.spinner_layout, getResources().getStringArray(R.array.LineTypes));
    myAdapter.setDropDownViewResource(R.layout.spinner_layout);
    spinner.setAdapter(myAdapter);

    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position2, long l) {


            switch (position2) {
                case 0:
                    quantity.setText("");
                    break;
                case 1:
                    quantity.setVisibility(View.INVISIBLE);
                    timeadded = 10;
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.INVISIBLE);
                    break;
                case 2:
                    quantity.setVisibility(View.INVISIBLE);
                    timeadded = 10;
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.INVISIBLE);
                    break;
                case 3:
                    quantity.setVisibility(View.INVISIBLE);
                    timeadded = 10;
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.INVISIBLE);
                    break;
                case 4:
                    quantity.setVisibility(View.VISIBLE);
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.VISIBLE);
                    Toast.makeText(getApplicationContext(), "Select Package Type", Toast.LENGTH_SHORT).show();
                    break;
                case 5:
                    quantity.setVisibility(View.VISIBLE);
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.VISIBLE);
                    Toast.makeText(getApplicationContext(), "Select Package Type", Toast.LENGTH_SHORT).show();
                    break;
                case 6:
                    quantity.setVisibility(View.VISIBLE);
                    duration.setText(timeadded + " Hours");
                    spinner2.setVisibility(View.VISIBLE);
                    Toast.makeText(getApplicationContext(), "Select Package Type", Toast.LENGTH_SHORT).show();
                    break;
                default:
                    break;

            }
        }


        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }

    });



    ArrayAdapter<String> myAdapter2 = new ArrayAdapter<String>(CreateLine.this,
            R.layout.spinner_layout, getResources().getStringArray(R.array.PackageTypes));
    myAdapter2.setDropDownViewResource(R.layout.spinner_layout);
    spinner2.setAdapter(myAdapter2);

    spinner2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {


            switch (position) {
                case 0:
                    quantity.setText("");
                    break;
                case 1:
                    quantity.setText(PackageType20);
                    timeadded = 28;
                    duration.setText(timeadded + " Hours");


                    break;
                case 2:
                    quantity.setText(PackageType30);
                    timeadded = 27;
                    duration.setText(timeadded + " Hours");

                    break;
                default:
                    break;
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }


    });

VerifyButton Java

        VerifyButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {



            spinnerSelection = String.valueOf(spinner.getSelectedItem());
            spinnerSelection2 = String.valueOf(spinner2.getSelectedItem());
            String q = quantity.getText().toString();
            String d = duration.getText().toString();

            DateTime datetime = new DateTime(yearNow, monthNow, dayNow, hourNow, minuteNow);
            DateTimeFormatter fmt = DateTimeFormat.forPattern("EE dd MM yyyy" + "\n" + " h:mm a ");
            String formattedtime = fmt.print(datetime);
            CalculateButton.setText(formattedtime);

            // Plus some hours, minutes, and seconds to the original DateTime.
            DateTimeFormatter fmt2 = DateTimeFormat.forPattern("EE dd MM yyyy" + "\n" + " h:mm a ");

            DateTime dateTime1 = datetime.plusHours(timeadded);
            String endtimecalc = fmt2.print(dateTime1);
            TextView endtime = findViewById(endtimetextView);
            endtime.setVisibility(View.VISIBLE);
            endtime.setText(endtimecalc);

            if (spinnerSelection !=null) {
                Toast.makeText(getApplicationContext(),"enter value",
                        Toast.LENGTH_LONG).show();
            }


            //INSERT DATA TO DATABASE
            boolean isInserted = myDb.insertData(
                    spinnerSelection,
                    spinnerSelection2,
                    q,
                    d,
                    formattedtime,
                    endtimecalc);


            if (isInserted == true)
                Toast.makeText(CreateLine.this, "Data Inserted Successfully", Toast.LENGTH_LONG).show();
            else
                Toast.makeText(CreateLine.this, "This line is already Active!", Toast.LENGTH_LONG).show();

            Intent intent = new Intent(getApplicationContext(), Dashboard.class);
            startActivity(intent);



        }
    });

Answer 1

在spinner.setAdapter（myAdapter）之后添加;

spinner.setAdapter(myAdapter)
spinner.setSelection(-1);

然后点击验证按钮：

  if (spinner.getSelectedItemPosition() == -1 || spinner2.getSelectedItemPosition() == -1 ){
         // showErrorMessage
  }
  else{
        //do your work
  }

对spinner2执行相同的操作

Answer 2

替换所有你的：

$('#b1').on('click',function(){
    alert("button #1 is clicked");
    $('#b2').click();
});
$('#b2').on('click',function(){
    alert("button #2 is clicked");
});

使用：

getApplicationContext()

并在以下行而不是getApplicationContext（）：

getContext()

使用您的班级名称，如下所示：

Intent intent = new Intent(getApplicationContext(), Dashboard.class);

您定义验证按钮的类。

在onNothingSelected方法中，将spinner的默认值设置为：

Intent intent = new Intent(YourClassName.this, Dashboard.class);

同时应用支票而不是：

ArrayList<String> list = getResources().getStringArray(R.array.LineTypes);

yourSpinner.setSelection(list[0]);

如：

 if (spinnerSelection !=null) {
            Toast.makeText(getApplicationContext(),"enter value",
                    Toast.LENGTH_LONG).show();
        }

选择了导入的微调器值，或者不允许选择按钮

2 个答案: