使用基于微调器选择的字符串填充EditText

Question

我创建了以下活动，该活动使用多个活动的意图传递Edittext值的数据。我希望能够根据微调器的用户选择填充EditText值。我尝试了下面的代码，但遇到了OnItemSelectedListener的问题。有什么建议？

public class Fragmentation_Rock_Properties extends AppCompatActivity {


    Spinner RockTypeSpinner;
    EditText RockDensityEditText;

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

        //set spinner and edittext
        RockTypeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            public void onItemSelected(AdapterView<?> arg0, View arg1,
                                       int arg2, long arg3) {
                // TODO Auto-generated method stub

                if (RockTypeSpinner.getSelectedItem().toString().equals("Sandstone")) {
                    RockDensityEditText.setText("1");
                } else if (RockTypeSpinner.getSelectedItem().toString().equals("Mudstone")) {
                    RockDensityEditText.setText("2");
                }
            }

            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub
            }
        });

        //Set intent to send data
        final Intent i = new Intent(this, Fragmentation_Rock_Jointing.class);
        Button button = findViewById(R.id.IntactRockNextbutton);
        button.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View v) {


                //Declare EditText
                EditText rockdensityedittext = findViewById(R.id.RockDensityEditText);
                EditText youngsmodulusedittext = findViewById(R.id.YoungsModulusEditText);
                EditText ucsedittext = findViewById(R.id.UCSEditText);

                //Set intent to pass edittexts

                i.putExtra("rockdensity", rockdensityedittext.getText().toString());
                i.putExtra("youngsmodulus", youngsmodulusedittext.getText().toString());
                i.putExtra("ucs", ucsedittext.getText().toString());
                startActivity(i);
            }
        }
        );

    }

}

Answer 1

RockTypeSpinner和RockDensityEditText是null。要使用变量，我们需要初始化它们。看我的代码。它可以帮助你。

public class Fragmentation_Rock_Properties extends AppCompatActivity {

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

        final EditText rockdensityedittext = findViewById(R.id.RockDensityEditText);
        final EditText youngsmodulusedittext = findViewById(R.id.YoungsModulusEditText);
        final EditText ucsedittext = findViewById(R.id.UCSEditText);
        // Replace ID_OF_YOUR_SPINNER by real value
        final Spinner rockTypeSpiner = findViewById(R.id.ID_OF_YOUR_SPINNER);

        rockTypeSpiner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            public void onItemSelected(AdapterView<?> arg0, View arg1,
                                       int arg2, long arg3) {
                String selectedItem = rockTypeSpiner.getSelectedItem().toString();
                if (selectedItem.equals("Sandstone")) {
                    rockdensityedittext.setText("1");
                } else if (selectedItem.equals("Mudstone")) {
                    rockdensityedittext.setText("2");
                }
            }

            public void onNothingSelected(AdapterView<?> arg0) {
            }
        });

        //Set intent to send data
        final Intent i = new Intent(this, Fragmentation_Rock_Jointing.class);
        Button button = findViewById(R.id.IntactRockNextbutton);
        button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {               
                //Set intent to pass edittexts
                i.putExtra("rockdensity", rockdensityedittext.getText().toString());
                i.putExtra("youngsmodulus", youngsmodulusedittext.getText().toString());
                i.putExtra("ucs", ucsedittext.getText().toString());
                startActivity(i);
            }
        }
        );
    }

}