如何使用微调器下拉菜单更改TextView小部件上的文本
如何使用微调器下拉菜单更改TextView小部件上的文本
提问于 2019-10-18 18:32:28
我有个实际的事情要做。我必须做一个测量转换器安卓应用程序使用java。它涉及到使用微调器下拉菜单。如图所示，如果用户在微调器下拉菜单中选择英里到公里，TextView小部件将显示英里和公里。然而，我不能让它工作。现在，我将为您提供示例代码。
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements
TextView.OnEditorActionListener, AdapterView.OnItemSelectedListener {
private Spinner conversions;
private String list [];
private TextView u1;
private TextView u2;
private EditText input;
private TextView convertedUnit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
conversions = findViewById(R.id.converterSelector);
u1 = findViewById(R.id.unit1Lbl);
u2 = findViewById(R.id.unit2Lbl);
input = findViewById(R.id.enterNum);
convertedUnit = findViewById(R.id.convertedNumLbl);
list = getResources().getStringArray(R.array.conversion_types);
// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.conversion_types, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Apply the adapter to the spinner
conversions.setAdapter(adapter);
conversions.setOnItemSelectedListener(this);
u1.setOnEditorActionListener(this);
}
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
// An item was selected. You can retrieve the selected item using
// parent.getItemAtPosition(pos)
String menuComponent = parent.getItemAtPosition(pos).toString();
if(menuComponent.equals(pos)){
if(pos == 0) {
u1.setText(getString(R.string.milesLbl));
u2.setText(getString(R.string.km));
double mile = (double)
Double.parseDouble(String.valueOf(input.getText()));
double kiloMeter = mile * 1.6093;
convertedUnit.setText("" + kiloMeter);
}
}
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
}
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
return false;
}
@Override
public void onPointerCaptureChanged(boolean hasCapture) {
}
}我的应用程序崩溃，代码如下。你能找出问题是什么吗?如果你发现了问题，你能粘贴正确的代码来修复它吗？谢谢。
回答 1
Stack Overflow用户
发布于 2019-10-18 19:05:24
OnItemSelected你可以得到这个位置并根据它执行一个方法。
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
switch (i){
case 0: milesToKilo();
break;
case 1: kiloTomiles();
break;
case 2: inchesToCenti();
break;
case 3: centiToInches();
break;
default:
}
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
public void milesToKilo(){
u1.setText("Miles");
u2.setText("Kilos");
// rest of calculations
}
public void kiloTomiles(){
u1.setText("Miles");
u2.setText("Kilos");
// rest of calculations
}
public void inchesToCenti(){
u1.setText("inches");
u2.setText("Centi");
// rest of calculations
}
public void centiToInches(){
u1.setText("Centi");
u2.setText("Inches");
// rest of calculations
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/58449053
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