Question

我按照Android开发者网站上的说明创建了您的第一个应用。前几个平台测试对我来说很好，但是在尝试使用意图将消息从一个活动传递到另一个活动时它向南移动。具体来说，当我按下文本字段输入输入时，应用程序会立即崩溃（请参阅https://developer.android.com/training/basics/firstapp/starting-activity.html#DisplayMessage处的预期行为）。

一年多以前报道了一个与我的问题似乎相同的问题，没有令人满意的答案：Could not find a method sendMessage(View) in the activity class

我相当确定的一些事情不问题：

扩展了ActionBarActivity - 我知道这已被弃用但在此错误之前它运行良好。
硬编码onClick in xml - 我听说这不是最佳做法，但我怀疑官方的Android教程会指示它，如果它至少没有工作。

我自己的基本和不明智的诊断是，即使我在MyActivity.java中编写了sendMessage（View视图）方法，运行时并不认为它存在。我迷失了为什么。这是我的代码：

MyActivity.java：

package org.example.myfirstapp;


import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;


public class MyActivity extends ActionBarActivity {
    public final static String EXTRA_MESSAGE = "org.example.myfirstapp.MESSAGE";

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

    @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);
    }

    /** Called when the user clicks the Send button */
    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);
    }
}

activity_my.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">

<EditText android:id="@+id/edit_message"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:hint="@string/edit_message"
    android:onClick="sendMessage"/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/button_send"/>

</LinearLayout>

DisplayMessageActivity.java：

package org.example.myfirstapp;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;


public class DisplayMessageActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //get message from intent
        Intent intent = getIntent();
        String message = intent.getStringExtra(MyActivity.EXTRA_MESSAGE);
        //create text view
        TextView textView = new TextView(this);
        textView.setTextSize(40);
        textView.setText(message);
        //set text view as activity layout
        setContentView(textView);
    }

    @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);
    }
}

崩溃输出：

    --------- beginning of crash
05-30 11:41:37.734  23198-23198/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: org.benwiley.myfirstapp, PID: 23198
    java.lang.IllegalStateException: Could not find a method sendMessage(View) in the activity class android.support.v7.internal.widget.TintContextWrapper for onClick handler on view class android.support.v7.widget.AppCompatEditText with id 'edit_message'
            at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4780)
            at android.view.View$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)
     Caused by: java.lang.NoSuchMethodException: sendMessage [class android.view.View]
            at java.lang.Class.getMethod(Class.java:664)
            at java.lang.Class.getMethod(Class.java:643)
            at android.view.View$1.onClick(View.java:4000)
            at android.view.View.performClick(View.java:4780)
            at android.view.View$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)

提前非常感谢。我很丢失。附：我正在使用API 22和Build Tools 22.0.1。

Answer 1

我认为你有很多错误

activity_my.xml

<button
android:id="@+id/btnsend"
android:layout_width="wrap_content" 
android:layout_height="wrap_content">

在MyActivity.java中：

Button button = (Button).findViewById(R.id.btnsend);
button.setOnClickListener(new View.OnClickListener(){ 
public void onClick(View v) {
 EditText editText = (EditText) findViewById(R.id.edit_message); 
sendMessage(v);}
});

AndroidManifest.xml中的

：

<activity 
android:name=".DisplayMessageActivity"
android:label="@string/title_activity_display_message">

Answer 2

在遵循相同的教程时，我在activity_my.xml文件中犯了同样的错误，将属性android:onClick="sendMessage"放在EditText元素中。

当然应该在Button元素中！最终的activity_my.xml应如下所示：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">

 <EditText android:id="@+id/edit_message"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:hint="@string/edit_message"/>

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

</LinearLayout>

Android无法在Activity类

2 个答案: