Android ImageButton不显示图像

Question

我是Java新手，正在开发一个简单的mediaplayer：两个图像按钮存在问题：运行应用程序时，不显示相关图像。 这是我的代码：

JAVA：

package lukes.mediaplayer;

import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.app.Activity;

public class alpha extends Activity implements View.OnClickListener {
    SeekBar seekBar_alpha;
    ImageButton btPlay_alpha;
    ImageButton btStop_alpha;
    MediaPlayer mp;
    Handler seekHandler = new Handler();
    ImageView display;

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alpha);

        display = (ImageView) findViewById(R.id.imagetop);
        display.setOnClickListener(this);

        getInit();
        seekUpdation();
    }

    public void getInit() {
        seekBar_alpha = (SeekBar) findViewById(R.id.seekBar_alpha);
        btPlay_alpha = (ImageButton) findViewById(R.id.btPlay_alpha);
        btStop_alpha = (ImageButton) findViewById(R.id.btStop_alpha);
        btPlay_alpha.setOnClickListener(this);
        btStop_alpha.setOnClickListener(this);
        mp = MediaPlayer.create(this, R.raw.alpha_audio);
        seekBar_alpha.setMax(mp.getDuration());
    }

    Runnable run = new Runnable() {

        @Override
        public void run() {
            seekUpdation();
        }
    };

    public void seekUpdation() {
        seekBar_alpha.setProgress(mp.getCurrentPosition());
        seekHandler.postDelayed(run, 1000);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.imagetop:
                Intent intent = new Intent (alpha.this, alpha_img.class);
                startActivity(intent);

            case R.id.btPlay_alpha:
                mp.start();
                break;

            case R.id.btStop_alpha:
                mp.pause();
        }
    }

    @Override
    protected void onPause(){
        super.onPause();
        if (mp!=null && mp.isPlaying()){
            mp.pause();
        }
    }

}

“ btPlay_alpha”和“ btStop_alpha”图像按钮不显示其图像。 你能帮我解决这个问题吗？ 谢谢！

---

大家好，我添加了XML代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout

    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".alpha">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/main.appbar"
        android:layout_width="match_parent"
        android:layout_height="350dp"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/main.collapsing"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginEnd="64dp"
            app:expandedTitleMarginStart="48dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <android.support.v7.widget.Toolbar
                android:id="@+id/main.toolbar"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

            <ImageButton
                android:id="@+id/imagetop"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@android:color/black"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                android:src="@drawable/alpha"
                app:layout_collapseMode="parallax" />

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="16dp"
                app:cardElevation="5dp"
                app:cardUseCompatPadding="true">

                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:id="@+id/textView3"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:fontFamily="sans-serif-condensed"
                        android:lineSpacingExtra="8dp"
                        android:padding="16dp"
                        android:text="@string/alpha_title"
                        android:textColor="@color/colorPrimary"
                        android:textSize="24sp"
                        android:textStyle="bold" />

                    <RelativeLayout
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_gravity="center"
                        android:paddingLeft="16dp"
                        android:paddingRight="16dp">


                        <ImageButton
                            android:id="@+id/btStop_alpha"
                            android:layout_width="60dp"
                            android:layout_height="55dp"
                            android:layout_alignParentLeft="true"
                            android:layout_alignParentStart="true"
                            android:layout_alignParentTop="true"
                            android:backgroundTint="@color/lightRed"
                            android:elevation="6dp"
                            android:padding="16dp"
                            app:srcCompat="@android:drawable/ic_media_pause" />

                        <ImageButton
                            android:id="@+id/btPlay_alpha"
                            android:layout_width="60dp"
                            android:layout_height="55dp"
                            android:layout_alignParentTop="true"
                            android:layout_gravity="center"
                            android:layout_toEndOf="@+id/btStop_alpha"
                            android:layout_toRightOf="@+id/btStop_alpha"
                            android:backgroundTint="@color/lightRed"
                            android:elevation="6dp"
                            app:srcCompat="@android:drawable/ic_media_play" />

                        <SeekBar
                            android:id="@+id/seekBar_alpha"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content"
                            android:layout_centerVertical="true"
                            android:layout_toEndOf="@+id/btPlay_alpha"
                            android:layout_toRightOf="@+id/btPlay_alpha"
                            android:max="100" />

                    </RelativeLayout>

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content">

                        <TextView
                            android:id="@+id/textView"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content"
                            android:fontFamily="serif"
                            android:lineSpacingExtra="8dp"
                            android:padding="16dp"
                            android:text="@string/alpha_text"
                            android:textSize="18sp" />

                    </LinearLayout>
                </LinearLayout>
            </android.support.v7.widget.CardView>
        </LinearLayout>
    </android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>

谢谢您的支持！

Answer 1

我看到您正在扩展Activity而不是AppCompatActivity。 在xml中，您正在设置属性srcCompat; 确保从Android支持库23.3.0开始，只能通过app：srcCompat加载支持向量可绘制对象。

您需要向您的build.gradle文件添加vectorDrawables.useSupportLibrary = true

// Gradle Plugin 2.0+  
android {  
 defaultConfig {  
   vectorDrawables.useSupportLibrary = true  
  }  
}