【发布时间】：2018-10-27 14:24:41
【问题描述】：
我遇到了与其他人在 SO 上遇到的问题相同的问题。在我的项目中，android studio 说它无法解析符号 R。
奇怪的是它构建得很好。我的问题类似于 SO 上的this 帖子。
他的回答中唯一提到的是，与他人合作时可能会出现此问题，并且由于错误，我不得不从 GitHub 下载项目的主副本。
我在我的项目中尝试了以下方法：
清洁项目 重建项目。 重命名所有拼写错误的文件（helloworld 到 hello_world） 将项目名称从 MyApp-Master 更改为原始名称 MyApp。 运行 android lint 以查找代码语法中的任何错误并修复它们 使用值而不是硬编码属性
我还梳理了 SO 帖子 here 和 here 但不幸的是这些建议没有帮助。
我正在使用 android studio 3.2.1
我没有包括所有未解析 R 的类，因为它在所有类中。 但这里是 MainActivity.class
package com.example.cohen.theepiccalculator;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private DrawerLayout drawerLayout;
private int drawerId;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setDisplayHomeAsUpEnabled(true);
}
if (actionBar != null) {
actionBar.setHomeAsUpIndicator(R.drawable.ic_button_drop_down);
}
drawerLayout = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
drawerId = menuItem.getItemId();
menuItem.setChecked(true);
selectItem(drawerId);
drawerLayout.closeDrawers();
return true;
}
});
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()){
case android.R.id.home:
drawerLayout.openDrawer(GravityCompat.START);
return true;
}
return super.onOptionsItemSelected(item);
}
private void selectItem(int position){
switch (position){
case R.id.nav_currency :
Intent intentC = new Intent(MainActivity.this, InputActivityCurrency.class);
startActivity(intentC);
Toast.makeText(MainActivity.this,"Currency", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_length :
Intent intentL = new Intent(MainActivity.this, InputActivityLength.class);
startActivity(intentL);
Toast.makeText(MainActivity.this,"Length", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_weight :
Intent intentW = new Intent(MainActivity.this, InputActivityWeight.class);
startActivity(intentW);
Toast.makeText(MainActivity.this,"Weight", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_temp :
Intent intentT = new Intent(MainActivity.this, InputActivityTemperature.class);
startActivity(intentT);
Toast.makeText(MainActivity.this,"Temp", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_area :
Intent intentA = new Intent(MainActivity.this, InputActivityArea.class);
startActivity(intentA);
Toast.makeText(MainActivity.this,"Area", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_speed :
Intent intentS = new Intent(MainActivity.this, InputActivitySpeed.class);
startActivity(intentS);
Toast.makeText(MainActivity.this,"Speed", Toast.LENGTH_SHORT).show();
break;
case R.id.nav_vol :
Intent intentV = new Intent(MainActivity.this, InputActivityVolume.class);
startActivity(intentV);
Toast.makeText(MainActivity.this,"Vol", Toast.LENGTH_SHORT).show();
break;
}
}
}
这里是相关的activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/bluetwo"
android:fitsSystemWindows="true"
android:id="@+id/drawer_layout">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<include
android:id="@+id/tbar"
layout="@layout/my_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true" />
</RelativeLayout>
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button
android:id="@+id/equels"
android:layout_width="101dp"
android:layout_height="183dp"
android:layout_alignBottom="@id/point"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:background="@drawable/ic_button_equals_orange" />
<Button
android:id="@+id/eight"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toRightOf="@id/seven"
android:layout_toEndOf="@id/seven"
android:layout_alignBottom="@id/seven"
android:background="@drawable/ic_button_eight_blue"
android:layout_marginLeft="1dp"
android:layout_marginStart="1dp" />
<Button
android:id="@+id/nine"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignBottom="@id/eight"
android:layout_marginStart="1dp"
android:layout_toEndOf="@id/eight"
android:layout_toRightOf="@id/eight"
android:background="@drawable/ic_button_nine_blue"
android:layout_marginLeft="1dp" />
<Button
android:id="@+id/times"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toEndOf="@id/persent"
android:layout_toRightOf="@id/persent"
android:layout_alignBottom="@id/persent"
android:layout_marginLeft="1dp"
android:background="@drawable/ic_button_times_blue"
android:layout_marginStart="1dp" />
<Button
android:id="@+id/devide"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toRightOf="@id/times"
android:layout_toEndOf="@id/times"
android:layout_alignBottom="@id/times"
android:layout_marginLeft="1dp"
android:layout_marginStart="1dp"
android:background="@drawable/ic_button_devide_blue"
/>
<TextView
android:id="@+id/ValueTextBox"
android:layout_width="422dp"
android:layout_height="145dp"
android:layout_alignBottom="@id/back"
android:layout_marginBottom="90dp"
android:background="@color/bluesemi"
android:gravity="center_horizontal|center|end"
android:padding="6dp"
android:textSize="50sp"
app:fontFamily="@font/zonaprothin"
android:textColor="@color/bluetwo"/>
<Button
android:id="@+id/back"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignBottom="@id/seven"
android:layout_marginBottom="92dp"
android:background="@drawable/ic_button_back_space_blue"/>
<Button
android:id="@+id/persent"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toEndOf="@id/back"
android:layout_toRightOf="@id/back"
android:layout_alignBottom="@id/back"
android:layout_marginLeft="1dp"
android:layout_marginStart="1dp"
android:background="@drawable/ic_button_persentage_blue"
/>
<Button
android:id="@+id/four"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignBottom="@+id/one"
android:layout_marginBottom="92dp"
android:background="@drawable/ic_button_four_blue" />
<Button
android:id="@+id/five"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignStart="@+id/four"
android:layout_alignLeft="@+id/four"
android:layout_alignBottom="@id/four"
android:layout_marginStart="103.5dp"
android:layout_marginLeft="103.5dp"
android:layout_marginBottom="0dp"
android:background="@drawable/ic_button_five_blue" />
<Button
android:id="@+id/six"
android:layout_alignBottom="@id/five"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_marginLeft="207dp"
android:layout_marginStart="207dp"
android:background="@drawable/ic_button_six_blue"/>
<Button
android:id="@+id/one"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignTop="@id/zero"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_marginTop="-92dp"
android:background="@drawable/ic_button_one_blue" />
<Button
android:id="@+id/two"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignBottom="@id/one"
android:layout_marginStart="1dp"
android:layout_marginLeft="1dp"
android:layout_toEndOf="@id/one"
android:layout_toRightOf="@id/one"
android:background="@drawable/ic_button_two_blue" />
<Button
android:id="@+id/three"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toEndOf="@id/two"
android:layout_toRightOf="@id/two"
android:layout_alignBottom="@id/two"
android:layout_marginLeft="1dp"
android:layout_marginStart="1dp"
android:background="@drawable/ic_button_three_blue"
/>
<Button
android:id="@+id/plus"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_above="@+id/equels"
android:layout_marginStart="1dp"
android:layout_marginLeft="1dp"
android:layout_toEndOf="@id/six"
android:layout_toRightOf="@id/six"
android:layout_alignBottom="@+id/six"
android:background="@drawable/ic_button_plus_blue" />
<Button
android:id="@+id/minus"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_toEndOf="@id/nine"
android:layout_toRightOf="@id/nine"
android:layout_alignBottom="@id/nine"
android:layout_marginLeft="1dp"
android:layout_marginStart="1dp"
android:background="@drawable/ic_button_minus_blue" />
<Button
android:id="@+id/seven"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_alignBottom="@id/four"
android:layout_marginBottom="92dp"
android:background="@drawable/ic_button_seven_blue" />
<Button
android:id="@+id/point"
android:layout_width="102dp"
android:layout_height="91dp"
android:layout_above="@+id/zero"
android:layout_alignBottom="@id/zero"
android:layout_toEndOf="@id/zero"
android:layout_toRightOf="@id/zero" />
<Button
android:id="@+id/zero"
android:layout_width="205dp"
android:layout_height="91dp"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="0dp"
android:layout_marginLeft="0dp"
android:layout_marginEnd="1dp"
android:layout_marginRight="1dp"
android:layout_marginBottom="0dp"
android:background="@drawable/ic_button_zero_blue" />
</RelativeLayout>
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header"
app:menu="@menu/draw_items" />
</android.support.v4.widget.DrawerLayout>
如果我遗漏了任何可能对您有帮助的内容，请告诉我。
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