java - 找不到符号变量 edit_message

Question

我现在正在阅读 Android Studio 开发人员指南并尝试完成他们的示例应用程序。我已经一步步地遵循了所有的事情，但是我遇到了一个令人困惑的问题，即 IDE 无法识别某个变量 edit_message。我查找了其他出现此错误的人，他们的问题不是在 strings.xml 中声明字符串，但我已确保这样做。这是我发生错误的主类:

package com.example.darks.videodeck;


import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;


public class MyActivity extends AppCompatActivity {
    public final static String EXTRA_MESSAGE = "com.example.darks.videodeck";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_my, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
    public void sendMessage(View view)
    {
        Intent intent = new Intent(this, DisplayMessageActivity.class);
        EditText editText = (EditText) findViewById(R.id.edit_message);
        String message = editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }
}

这是 strings.xml 文件，您可以看到该文件中声明的 edit_message 和未被识别的 edit_message 是相同的:

<resources>
    <string name="app_name">VideoDeck</string>
    <string name="action_settings">Settings</string>
    <string name="edit_message">Enter a message</string>
    <string name="button_send">Send</string>
    <string name="title_activity_display_message">My Message</string>

</resources>

如有任何帮助，我们将不胜感激。

Answer 1

R.id.edit_message 是一个layout id，所以你必须在 EditText 上设置它在您的 activity_my.xml 布局中。像这样:

activity_my.xml

<EditText
    android:id="@+id/edit_message"
    android:layout_width=...
    android:layout_height=...
/>