Android Intent应用程序崩溃

Question

I'm trying to create a very small application for a project. I have two buttons that call applications with implicit intents, but whenever I press either, the application (the one I'm creating) keeps crashing. What's going on? Here's the code:

package com.messengerassist;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    public void startPostmates() {
        Intent launchIntent = getPackageManager().getLaunchIntentForPackage("com.postmates.android.courier");
        startActivity(launchIntent);
    }
    public void startCaviar() {
        Intent launchIntent = getPackageManager().getLaunchIntentForPackage("com.trycaviar.courier");
        startActivity(launchIntent);
    }
}

and then

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.messengerassist.MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Postmates"
        android:id="@+id/startPostmates"
        android:onClick="startPostmates"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Caviar"
        android:id="@+id/startCaviar"
        android:onClick="Start Caviar"
        android:layout_below="@+id/startPostmates"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

Here is what logcat is giving me:

12-21 20:10:28.919 4108-4108/com.messengerassist E/AndroidRuntime: FATAL EXCEPTION: main
                                                                   Process: com.messengerassist, PID: 4108
                                                                   java.lang.IllegalStateException: Could not find method startPostmates(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'startPostmates'
                                                                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:307)
                                                                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:266)
                                                                       at android.view.View.performClick(View.java:4789)
                                                                       at android.view.View$PerformClick.run(View.java:19881)
                                                                       at android.os.Handler.handleCallback(Handler.java:739)
                                                                       at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                       at android.os.Looper.loop(Looper.java:135)
                                                                       at android.app.ActivityThread.main(ActivityThread.java:5292)
                                                                       at java.lang.reflect.Method.invoke(Native Method)
                                                                       at java.lang.reflect.Method.invoke(Method.java:372)
                                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
                                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

Answer 1

When you register a click listener method in your XML ,The method should take View as it's parameter. From the logcat changing the method signature like this may solve the problem

 public void startPostmates(View view) { ...}
 public void startCaviar(View view) {...}