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分享Android ImageView 控件方法使用出错
final ImageView imageView = (ImageView) findViewById(R.id.imageView);
imageView.setImageResource(R.drawable.temp);
error：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference
at com.example.administrator.correct.MainActivity$1.onItemClick(MainActivity.java:65)
imageView.setImageResource(R.drawable.temp);
error：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference
at com.example.administrator.correct.MainActivity$1.onItemClick(MainActivity.java:65)
...全文
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犟果 2016-09-04
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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity$PlaceholderFragment"
android:id="@+id/relative_layout">
<TextView android:id="@+id/section_label" android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:src = "@drawable/helin"
android:scaleType="fitCenter"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
RelativeLayout relativeLayout = (RelativeLayout)findViewById(R.id.relative_layout);
final ImageView imageView = (ImageView) relativeLayout.findViewById(R.id.imageView);
imageView.setImageResource(R.drawable.temp);
error:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.RelativeLayout.findViewById(int)' on a null object reference
at com.example.administrator.correct.MainActivity.onCreate(MainActivity.java:59)
[/quote]
你试试这样，final RelativeLayout relativeLayout = (RelativeLayout)getLayoutInflater().inflate(R.layout.你的XML文件的名字,null);然后再relativeLayout.findbyid()。[/quote]
谢谢，不报错了。
犟果 2016-08-29
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<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$PlaceholderFragment"
android:id="@+id/relative_layout">
<TextView android:id="@+id/section_label" android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:src = "@drawable/helin"
android:scaleType="fitCenter"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
RelativeLayout relativeLayout = (RelativeLayout)findViewById(R.id.relative_layout);
final ImageView imageView = (ImageView) relativeLayout.findViewById(R.id.imageView);
imageView.setImageResource(R.drawable.temp);
error:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.RelativeLayout.findViewById(int)' on a null object reference
at com.example.administrator.correct.MainActivity.onCreate(MainActivity.java:59)
mhq42978 2016-08-29
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估计是把id写错了吧，或者对应的布局文件中根本没有这个控件
猿在古城 2016-08-29
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检查下是不是对应布局文件的imageView
qq_34421327 2016-08-29
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可以 ，很清爽，啊啊啊啊啊
哎，真难 2016-08-29
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绑定错误咯，看下控件信息
Chary Liu 2016-08-29
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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity$PlaceholderFragment"
android:id="@+id/relative_layout">
<TextView android:id="@+id/section_label" android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:src = "@drawable/helin"
android:scaleType="fitCenter"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
RelativeLayout relativeLayout = (RelativeLayout)findViewById(R.id.relative_layout);
final ImageView imageView = (ImageView) relativeLayout.findViewById(R.id.imageView);
imageView.setImageResource(R.drawable.temp);
error:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.RelativeLayout.findViewById(int)' on a null object reference
at com.example.administrator.correct.MainActivity.onCreate(MainActivity.java:59)
[/quote]
你试试这样，final RelativeLayout relativeLayout = (RelativeLayout)getLayoutInflater().inflate(R.layout.你的XML文件的名字,null);然后再relativeLayout.findbyid()。
一不小心_ 2016-08-28
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你可以把那部分的代码贴出来
Chary Liu 2016-08-28
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空对象，没有找到这个控件，你的这个控件是不是在viewpager的其中一页的XML文件里里或者某个对话框的布局文件里，提示一下你findbyid这个方法前面还有一个this，就是说比如你可以先找到这个组件所在的linelayout，暂时起名为l吧，然后在l.findbyid就可以了。
