Java 发送一些数据

我在youtube上看android studio发送数据教程 然后当我遵循它并执行程序时，我的程序总是说android停止工作

content\u main.xml

}

SecondActivity.java

public class MainActivity extends AppCompatActivity {
EditText message_text;
public final static String MESSAGE_KEY = "dproject.user.myapplication.message_key";

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

public void sendMessage (View view)
{
    message_text=(EditText)findViewById(R.id.message_text);
    String message = message_text.getText().toString();
    Intent intent = new Intent(this,SecondActivity.class);
    intent.putExtra(MESSAGE_KEY,message);
    startActivity(intent);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();

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

    return super.onOptionsItemSelected(item);
}

public class MainActivity extends AppCompatActivity {
EditText message_text;
public final static String MESSAGE_KEY = "dproject.user.myapplication.message_key";

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

public void sendMessage (View view)
{
    message_text=(EditText)findViewById(R.id.message_text);
    String message = message_text.getText().toString();
    Intent intent = new Intent(this,SecondActivity.class);
    intent.putExtra(MESSAGE_KEY,message);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

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

    return super.onOptionsItemSelected(item);
}

}

logcat

04-13 03:11:41.796 10106-10106/dproject.user.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: dproject.user.myapplication, PID: 10106
java.lang.IllegalStateException: Could not find method SendMessage(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton
  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:327)
  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
  at android.view.View.performClick(View.java:4780)
  at android.view.View$PerformClick.run(View.java:19866)
  at android.os.Handler.handleCallback(Handler.java:739)
  at android.os.Handler.dispatchMessage(Handler.java:95)
  at android.os.Looper.loop(Looper.java:135)
  at android.app.ActivityThread.main(ActivityThread.java:5254)
  at java.lang.reflect.Method.invoke(Native Method)
  at java.lang.reflect.Method.invoke(Method.java:372)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

确保

AndroidManifest.xml

文件中存在

SecondActivity

在XML中，从

按钮中删除
android:onClick=“SendMessage”
，并为
按钮提供
id
：

<Button
   android:id="@+id/button"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="@string/Button_text" />

---

你在用什么Android设备/模拟器进行测试？你的代码是什么API级别的？我正在使用genymotion作为模拟器。API级别为21请发布错误日志以准确了解发生了什么。MainActivity和SecondActivity看起来相同。堆栈跟踪在哪里..我的第二个活动存在于androidManifest.xml中，我移动了代码，但当我执行程序时，模拟器仍然显示“很不幸，我的应用程序已停止”

<activity android:name=".SecondActivity">

...........
......................

EditText message_text;
Button button;

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

    message_text = (EditText) findViewById(R.id.message_text);
    button = (Button) findViewById(R.id.button);

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            sendMessage();
        }
    }); 

    ....................
    ........................    
}

public void sendMessage()
{
    String message = message_text.getText().toString();
    Intent intent = new Intent(MainActivity.this, SecondActivity.class);
    intent.putExtra(MESSAGE_KEY,message);
    startActivity(intent);
}

<Button
   android:id="@+id/button"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="@string/Button_text" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/Button_text"
android:onClick="SendMessage"
/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/Button_text"
    android:onClick="sendMessage"
    />