Question

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

content_main.xml

android:id="@+id/content_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:orientation="vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main"
tools:context="dproject.user.myapplication.MainActivity">

<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/message_text"
    android:hint="@string/hint_message" />

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

MainActivity.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);
}

}

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);

}

@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的

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)

Answer 1

确保SecondActivity文件中存在AndroidManifest.xml。

<activity android:name=".SecondActivity">

更新MainActivity，如下所示：

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

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);
}

在您的XML中，从android:onClick="SendMessage"移除Button并向id提供Button：

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

Answer 2

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

在这里，您告诉按钮调用方法SendMessage（大写）。但在您的活动中，只有一种方法sendMessage（小写）。将XML更改为以下内容，它应该可以工作：

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

发送一些数据

2 个答案: