我在drawables文件夹中有一个名为down.png
的图像,但每次运行应用程序时,它都会在创建时崩溃。
这是我的MainActivity
代码:
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ImageView sss = (ImageView) findViewById(R.id.sss);
Button ddd = (Button) findViewById(R.id.button);
ddd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//sss.setImageResource(R.drawable.down);
sss.setBackgroundResource(R.drawable.down);
//sss.setImageDrawable(getResources().getDrawable(R.drawable.down));
}
});
}
这是我正在使用的XML:
<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:id="@+id/activity_main_layout"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<ImageView
android:layout_width="fill_parent"
android:layout_height="200dp"
android:id="@+id/sss"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Button"
android:id="@+id/button"
android:layout_below="@+id/sss"
android:layout_alignParentStart="true"
android:layout_marginTop="111dp" />
</RelativeLayout>
我的Logcat输出:
04-28 07:11:09.637 1359-1359/prosis.teste D/AndroidRuntime﹕ Shutting down VM
04-28 07:11:09.637 1359-1359/prosis.teste W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb3a99ba8)
04-28 07:11:09.687 1359-1359/prosis.teste E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: prosis.teste, PID: 1359
java.lang.RuntimeException: Unable to start activity ComponentInfo{prosis.teste/prosis.teste.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at prosis.teste.MainActivity.onCreate(MainActivity.java:35)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
04-28 07:11:14.327 1359-1359/prosis.teste I/Process﹕ Sending signal. PID: 1359 SIG: 9
评论中的所有命令都是我尝试过但失败的地方。 line 35
(出现在logcat中的那个)是进行更改的代码所在的行;
为什么那段代码导致崩溃?
答案 0 :(得分:1)
你应该使用
setImageResource(R.drawable.down);
setImageDrawable(getResources().getDrawable(R.drawable.down));
而不是setBackgroundResource(R.drawable.img1);
。
答案 1 :(得分:0)
首先将图像放入图像视图中,然后尝试使按钮,textView,editText等透明(无需动态设置,可以通过xml进行更改)。
答案 2 :(得分:0)
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ImageView sss = (ImageView) findViewById(R.id.sss);
Button ddd = (Button) findViewById(R.id.button);
ddd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sss.setBackgroundResource(R.drawable.ic_launcher);
}
});
}
}
使用此代码....我想你忘了添加 setContentView()方法......
答案 3 :(得分:0)
Use this simple code to draw in background image at ImageView
<ImageView
android:id="@+id/img"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/ic_launcher"
/>
or
<ImageView
android:id="@+id/img"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/ic_launcher"
/>
or
programmatically
img..setBackgroundResource(R.drawable.ic_launcher);