我正在尝试使用触发声音的按钮编写应用程序,并希望按钮仅在按下时才可见。但是当我添加setVisibility方法时,它会崩溃我的应用程序。这里是我的XML代码:setVisibility(View.INVISIBLE)让我的应用程序崩溃
<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=".MainActivity"
android:id="@+id/background"
android:background="@drawable/image"
android:orientation="horizontal">
<ImageButton
android:id="@+id/btn1"
android:layout_width="109dp"
android:layout_height="89dp"
android:scaleType="fitXY"
android:layout_marginTop="26dp"
android:src="@mipmap/oneeee"
android:background="@null"
android:contentDescription="@null"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="1dp" />
</RelativeLayout>
还有java的部分:
import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.RelativeLayout;
import static android.view.View.VISIBLE;
public class MainActivity extends Activity {
RelativeLayout background;
ImageButton btn;
MediaPlayer sound;
@Override
protected void onPause() {
super.onPause();
sound.release();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
btn.setVisibility(View.INVISIBLE);
setContentView(R.layout.activity_main);
sound = MediaPlayer.create(this, R.raw.kick);
btn = (ImageButton) findViewById(R.id.btn1);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MediaPlayer mp = MediaPlayer.create(getApplicationContext(), R.raw.kick);
btn.setVisibility(View.VISIBLE);
mp.start();
}
});
}
}
您在声明按钮之前设置了隐藏状态,放入btn.setVisibility(View.INVISIBLE); btn =(ImageButton)findViewById(R.id.btn1); – Santiago