android - 在 Android Studio 中构建应用程序时出现 Gradle 错误
问题描述
我正在尝试创建一个为我提供当前位置的 android 应用程序。由于在 Button 和 Text View 对象上创建,我收到错误。
依赖项:classpath 'com.android.tools.build:gradle:3.1.0'
活动主.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.suppalapat21.my_app.MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="238dp"
android:layout_height="0dp"
android:layout_marginBottom="20dp"
android:layout_marginTop="212dp"
android:text="Hello World!"
app:layout_constraintBottom_toTopOf="@+id/button"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.461" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="180dp"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView" />
</android.support.constraint.ConstraintLayout>
MainActivity.java
package com.example.suppalapat21.my_app;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
import java.util.Locale;
public class MainActivity extends AppCompatActivity implements LocationListener {
Button getLocationBtn;
TextView locationText;
LocationManager locationManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().hide();
setContentView(R.layout.activity_main);
getLocationBtn = (Button)findViewById(R.id.getLocationBtn);
locationText = (TextView)findViewById(R.id.locationText);
if (ContextCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION, android.Manifest.permission.ACCESS_COARSE_LOCATION}, 101);
}
getLocationBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getLocation();
}
});
}
void getLocation() {
try {
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 5000, 5, this);
}
catch(SecurityException e) {
e.printStackTrace();
}
}
@Override
public void onLocationChanged(Location location) {
locationText.setText("Latitude: " + location.getLatitude() + "\n Longitude: " + location.getLongitude());
try {
Geocoder geocoder = new Geocoder(this, Locale.getDefault());
List<Address> addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
locationText.setText(locationText.getText() + "\n"+addresses.get(0).getAddressLine(0)+", "+
addresses.get(0).getAddressLine(1)+", "+addresses.get(0).getAddressLine(2));
}catch(Exception e)
{
}
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(MainActivity.this, "Please Enable GPS and Internet", Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
}
这是我在 gradle build 后收到的错误消息。连接到设备并运行后构建失败。
Error:19:37:15.259 [ERROR] [system.err]
19:37:15.260 [ERROR] [system.err] getLocationBtn =
(Button)findViewById(R.id.getLocationBtn);
19:37:15.264 [ERROR] [system.err]
19:37:15.264 [ERROR] [system.err] symbol: variable getLocationBtn
19:37:15.264 [ERROR] [system.err] location: class id
19:37:15.301 [ERROR] [system.err]
19:37:15.302 [ERROR] [system.err] locationText =
(TextView)findViewById(R.id.locationText);
19:37:15.302 [ERROR] [system.err]
19:37:15.302 [ERROR] [system.err] symbol: variable locationText
19:37:15.302 [ERROR] [system.err] location: class id
19:37:15.421 [ERROR] [system.err] 2 errors
解决方案
错误的原因是 R.id.locationText 和 R.id.getLocationBtn
在下面的代码中将其更改为,因为您已将 textview-ID 设置为 textView 并将 button-ID 设置为 xml 文件中的按钮
getLocationBtn = (Button)findViewById(R.id.button);
locationText = (TextView)findViewById(R.id.textView);
推荐阅读
- java - java.lang.InstantiationError。类变得抽象
- google-apps-script - 如何更改我的范围以包括合并的单元格?
- javascript - 如何在日期选择器中获取特定的未来日期
- sphinx - 赋予匹配字段权重
- ruby - GEM 从哪里收集 gem 路径?
- windows - Get-Help 和 /? 之间的区别 在PowerShell中
- python - scattermapbox 中的选项“符号”不起作用
- python-3.x - 如何匹配列表和熊猫
- spring-boot - 基于 jsonb 映射中的键过滤条目的 JPA 规范
- reporting-services - 如果 ssrs 矩阵报告中的数据库中没有数据,则背景颜色不起作用