与edittext相关的问题
与edittext相关的问题
提问于 2015-10-11 06:09:57
我是java的新手，在将"input“转换为string时遇到了问题。
input = (EditText) findViewById(R.id.wpiszZapytanie);
String zapytanieDoUrl = input.getText().toString();它崩溃了，日志如下：
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{eu.qm.mood/eu.qm.mood.GIFActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2658)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.access$900(ActivityThread.java:172)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.os.Looper.loop(Looper.java:145)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5832)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:372)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at eu.qm.mood.GIFActivity.onCreate(GIFActivity.java:18)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.Activity.performCreate(Activity.java:6221)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2611)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.access$900(ActivityThread.java:172)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.os.Looper.loop(Looper.java:145)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5832)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:372)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
10-10 23:57:48.589 9423-9423/eu.qm.mood E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 正如我所看到的，在某处没有任何东西(null)。我知道这段代码看不到文本框中的内容，用户输入的内容。
编辑文本为content_main.xml格式
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" 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"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main" tools:context=".MainActivity">
<TextView android:text="@string/welcome" android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20dp"
android:textColor="@color/colorAccent"
android:textStyle="bold"
android:fontFamily="Roboto"
android:id="@+id/textView2"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/wpiszZapytanie"
android:singleLine="true"
android:layout_below="@+id/textView2"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:inputType="text"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/go"
android:id="@+id/doit"
android:onClick="goClick"
android:layout_below="@+id/wpiszZapytanie"
android:layout_centerHorizontal="true" />
</RelativeLayout>这是activity_gif.xml
<?xml version="1.0" encoding="utf-8"?>
<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="eu.qm.mood.GIFActivity">
<WebView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/GifResulttwo"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:layout_below="@+id/editText" />
</RelativeLayout>回答 3
Stack Overflow用户
发布于 2015-10-11 06:15:59
您的input变量为空，这就是出现异常的原因。
可能的原因：
- 我认为你对EditText使用了错误的
id。检查xml是否存在id为wpiszZapytanie - You的
EditText元素可能膨胀了错误的xml布局没有id为EditText的wpiszZapytanie - You可能在
setContentView()之前执行findViewById(R.id.wpiszZapytanie);正如@Pyrodante
所指出的那样
Stack Overflow用户
发布于 2015-10-11 06:23:50
正如pgitu所指出的:输入为空，当findViewById查找找不到它要查找的内容时，就会发生这种情况。出现这种情况的一个主要原因是在调用setContentView之前调用此函数。
在设置UI之前，您不能访问UI元素。因此，如果上面两个不是，那么这个可能就是。
Stack Overflow用户
发布于 2015-10-11 08:00:44
确保您的GIFActivity在您的onCreate方法上遵循此逻辑。
public class GIFActivity extends Activity {
EditText input;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); //First
setContentView(R.layout.activity_gif);//Second
input = (EditText) findViewById(R.id.wpiszZapytanie);//Third
String text = input.getText().toString();
}
}activity_gif.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/wpiszZapytanie"/>
</LinearLayout>页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/33059447
复制相关文章
相似问题
腾讯云开发者
