为什么意外隐式转换为`EditText`：布局标签是`TextView`

Question

我有一个问题，我正在尝试完成课程 Android 基础知识 02.3：隐式意图，但有一些错误

第一个是 Unexpected implicit cast to EditText: layout tag was TextView

第二个是在调用此 \ 方法时考虑在清单中添加声明；详情见https://g.co/dev/packagevisibility

应用运行时会立即自动停止，我在模拟器和真机上都试过了

源码实验室：https://developer.android.com/codelabs/android-training-activity-with-implicit-intent?index=..%2F..%2Fandroid-training#0

代码 MainActivity.java

package com.example.implicitintents;

import android.content.Intent;
import android.net.Uri;
import android.support.v4.app.ShareCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    private EditText mWebsiteEditText;
    private EditText mLocationEditText;
    private EditText mShareTextEditText;

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

        mWebsiteEditText = findViewById(R.id.website_edittext);
        mLocationEditText = findViewById(R.id.location_edittext);
        mShareTextEditText = findViewById(R.id.share_edittext);
    }

    public void openWebsite(View view) {
        String url = mWebsiteEditText.getText().toString();

        Uri webpage = Uri.parse(url);
        Intent intent = new Intent(Intent.ACTION_VIEW, webpage);

        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);
        } else {
            Log.d("ImplicitIntents", "Can't handle this intent!");
        }
    }

    public void openLocation(View view) {
        String loc = mLocationEditText.getText().toString();

        Uri addressUri = Uri.parse("geo:0,0?q=" + loc);
        Intent intent = new Intent(Intent.ACTION_VIEW, addressUri);

        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);
        } else {
            Log.d("ImplicitIntents", "Can't handle this intent!");
        }
    }

    public void shareText(View view) {
        String txt = mShareTextEditText.getText().toString();
        String mimeType = "text/plain";
        ShareCompat.IntentBuilder
                .from(this)
                .setType(mimeType)
                .setChooserTitle("Share this text with: ")
                .setText(txt)
                .startChooser();
    }
}

代码Activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context="MainActivity">

    <TextView
        android:id="@+id/website_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_uri" />

    <Button
        android:id="@+id/open_website_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="24dp"
        android:onClick="openWebsite"
        android:text="@string/button_uri" />

    <TextView
        android:id="@+id/location_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_loc" />

    <Button
        android:id="@+id/open_location_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="24dp"
        android:onClick="openLocation"
        android:text="@string/button_loc" />

    <TextView
        android:id="@+id/share_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_share" />

    <Button
        android:id="@+id/share_text_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="24dp"
        android:onClick="shareText"
        android:text="@string/button_share" />
</LinearLayout>

Answer 1

在您的 xml 文件中，您将三个元素声明为 Textview

<TextView
        android:id="@+id/website_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_uri" />
<TextView
        android:id="@+id/location_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_loc" />
<TextView
        android:id="@+id/share_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/edittext_share" />

然后在您的活动中将变量声明为 EditText

 private EditText mWebsiteEditText;
 private EditText mLocationEditText;
 private EditText mShareTextEditText;

这就是为什么你会看到这些铸造错误。

如果您想输入一些数据，请将您的 xml 文件更改为 EditText，或者如果您想显示一些文本但更改活动中变量的类型，请将其保留为 TextView。确保两者是同一类型