触摸按钮时如何使用MediaPlayer播放Mp3文件

Question

I get the error below every time I try to play the song, I successfully play the song when add the code in the main activity although when try playing in other of the activity the app crash and I just want to know why this happen and how I could solve the issue.

Error:

E/MediaPlayer: error (1, -2147483648)
D/MediaPlayer: create failed:
               java.io.IOException: Prepare failed.: status=0x1
                   at android.media.MediaPlayer._prepare(Native Method)
                   at android.media.MediaPlayer.prepare(MediaPlayer.java:1158)
                   at android.media.MediaPlayer.create(MediaPlayer.java:944)
                   at android.media.MediaPlayer.create(MediaPlayer.java:915)
                   at com.example.android.phaseup.AviationSongActivity.onCreate(AviationSongActivity.java:19)
                   at android.app.Activity.performCreate(Activity.java:6251)
                   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                   at android.app.ActivityThread.-wrap11(ActivityThread.java)
                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                   at android.os.Handler.dispatchMessage(Handler.java:102)
                   at android.os.Looper.loop(Looper.java:148)
                   at android.app.ActivityThread.main(ActivityThread.java:5422)
                   at java.lang.reflect.Method.invoke(Native Method)
                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.android.phaseup, PID: 1644
                  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.start()' on a null object reference
                      at com.example.android.phaseup.AviationSongActivity$1.onClick(AviationSongActivity.java:36)
                      at android.view.View.performClick(View.java:5204)
                      at android.view.View$PerformClick.run(View.java:21155)
                      at android.os.Handler.handleCallback(Handler.java:739)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:148)
                      at android.app.ActivityThread.main(ActivityThread.java:5422)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Application terminated.

Code MainActivity.java:

package com.example.android.phaseup;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

        //Call BlueBook Activity
        TextView blueBook = (TextView) findViewById(R.id.blue_book);

        //Set a click listener in that View
        blueBook.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent blueBookIntent = new Intent(MainActivity.this, BlueBookActivity.class);
                startActivity(blueBookIntent);
            }
        });

        //Call Aviation Song Activity
        TextView aviationSong = (TextView) findViewById(R.id.aviation_songs);

        //Set a click listener in that View
        aviationSong.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent aviationIntent = new Intent(MainActivity.this, AviationSongActivity.class);
                startActivity(aviationIntent);
            }
        });

        //Call Soldier's Creed Activity
        TextView soldierCreed = (TextView) findViewById(R.id.soldier_creed);

        //Set a click listener in that View
        soldierCreed.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent soldierCreedIntent = new Intent(MainActivity.this, SoldierCreedActivity.class);
                startActivity(soldierCreedIntent);
            }
        });

        //Call Room Inspection Activity
        TextView roomInspection = (TextView) findViewById(R.id.room_inspection);

        //Set a click listener in that View
        roomInspection.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent roomInspectionIntent = new Intent(MainActivity.this, RoomInspectionActivity.class);
                startActivity(roomInspectionIntent);
            }
        });

        //Call Wall Locker Inspection Activity
        TextView wallLocker = (TextView) findViewById(R.id.wall_Locker_inspection);

        //Set a click listener in that View
        wallLocker.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent wallLockerIntent = new Intent(MainActivity.this, WallLockerActivity.class);
                startActivity(wallLockerIntent);
            }
        });

        //Call ASU Inspection Activity
        TextView asuInspection = (TextView) findViewById(R.id.asu_inspection);

        //Set a click listener in that View
        asuInspection.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent asuIntent = new Intent(MainActivity.this, ASUActivity.class);
                startActivity(asuIntent);
            }
        });

        //Feedback button.
        TextView sendFeedBack = (TextView) findViewById(R.id.send_feedback);
        sendFeedBack.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent sendFeedbackIntent = new Intent(Intent.ACTION_SENDTO);
                sendFeedbackIntent.setData(Uri.parse("mailto: algenisromero@gmail.com"));
                sendFeedbackIntent.putExtra(Intent.EXTRA_SUBJECT, "Phase UP Support.");
                if (sendFeedbackIntent.resolveActivity(getPackageManager()) != null) {
                    startActivity(sendFeedbackIntent);
                }
            }
        });

    }
}

Code AviationSongActivity.java:

package com.example.android.phaseup;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class AviationSongActivity extends AppCompatActivity {

    //Media Player variable.
    MediaPlayer mMediaPlayer;

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

        //Create and Upload the MP3 file.
        mMediaPlayer = MediaPlayer.create(this, R.raw.aviationsong);


        //The aviation song text show in the screen.
        TextView textViewAviation = (TextView) findViewById(R.id.textview_aviation);
        textViewAviation.setText("High above the best, high above the best \n\n" +
                "We are Army Aviation USA, \n\n" +
                "proud and strong We meet the test \n\n" +
                "Skies filled with thunder \n\n" +
                "Wearing silver wings upon our chest \n\n" +
                "We meet the needs of Ground Command \n\n" +
                "As we aid the Nation's quest \n\n" +
                "Army Aviation, flying high above the best!");

        //Listener to play sound when user touched.
        Button playButton = (Button) findViewById(R.id.play_sound);

        playButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            mMediaPlayer.start();

            }
        });
    }
}

Code activity_aviation_song.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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">

    <LinearLayout
        android:id="@+id/activity_aviation_song"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context="com.example.android.phaseup.AviationSongActivity">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="170dp"
            android:background="@color/colorPrimaryDark">

            <Button
                android:id="@+id/play_sound"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="PLAY"
                android:textSize="56sp"
                android:textStyle="bold"
                android:textColor="@android:color/white"
                android:background="@null"/>

        </RelativeLayout>

        <TextView
            android:id="@+id/textview_aviation"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="32dp"
            android:gravity="center"
            android:textSize="18sp" />

    </LinearLayout>
</ScrollView>

You can find the full code of the app in my github account PhaseUp App

Thanks for your help!

Answer 1

Update your MP3 file so it is not empty or corrupt.

The code looks okay, otherwise.