Java MyFirstApp教程Android Studio 2.3生成错误重新显示额外消息和文本视图

MyFirstApp教程Android Studio在应用程序内接收消息时出现问题

生成错误如下所示：

错误：（17，60）错误：找不到符号变量EXTRA_消息
错误：（20，57）错误：找不到符号变量textView

我的消息接收器代码如下所示：

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_message);

    // Get the Intent that started this activity and extract the 
       string
    Intent intent = getIntent();
    String message = 
      intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

    // Capture the layout's TextView and set the string as its text
    TextView textView = (TextView) findViewById(R.id.textView);
    textView.setText(message);
}

    public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    /** Called when the user taps the Send button */
    public void sendMessage(View view) {
        Intent intent = new Intent(this, 
             DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(R.id.editText);
    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);
    startActivity(intent);
    }
}

注意：额外信息和文本视图为红色

发送代码如下所示：

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_message);

    // Get the Intent that started this activity and extract the 
       string
    Intent intent = getIntent();
    String message = 
      intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

    // Capture the layout's TextView and set the string as its text
    TextView textView = (TextView) findViewById(R.id.textView);
    textView.setText(message);
}

    public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    /** Called when the user taps the Send button */
    public void sendMessage(View view) {
        Intent intent = new Intent(this, 
             DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(R.id.editText);
    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);
    startActivity(intent);
    }
}

注意：在上面代码的这一行中：

public void sendMessage(View view) 

第一个“视图”有一条很浅的水平线穿过它，我得到一条错误消息，比如sendMessage（视图视图）被贬低了

我认为这个问题可能与

public void sendMessage(View view) 

还有它被贬低的代码信息。。。（？）

出现问题的教程链接：

---

检查MainActivity.java文件中的这一行，因为您的代码缺失

public static final String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";

---

检查MainActivity.java文件中的这一行，代码中缺少

public static final String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";

---

不确定是什么起作用，但玩弄它，让它发挥作用。检查导入语句，添加一到两个与文档匹配的语句。

不确定是什么起作用，但对其进行了处理并使其起作用。检查导入语句，添加一个或两个以匹配文档