无法在 TextView 上设置文本。给出 NullPointerException
unable to setText on TextView. Giving NullPointerException
我正在 textview 上设置文本,但它给了我 NullPointerException
这是我的 XML 文件。
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activitys.ScoreActivity">
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!--Score Card-->
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_margin="16dp"
app:cardCornerRadius="15dp"
app:cardElevation="6dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="-10dp"
android:text="Your Score"
android:textColor="@color/black"
android:textSize="30sp"
android:textStyle="bold" />
<TextView
android:id="@+id/scoreQTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="60dp"
android:layout_marginBottom="10dp"
android:text="100/200"/>
</androidx.cardview.widget.CardView>
</LinearLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
这是我的 activity 我在 TextView 上设置文本的地方
public class ScoreActivity extends AppCompatActivity {
private TextView scoreQTv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_score);
scoreQTv = findViewById(R.id.scoreQTv);
//and finded all widgets using findviewByID ...
scoreQTv.setText("My Score 18");
}
我无法在我的 TextView 上设置文本。如何设置文本,为什么会出现此错误?
当我检查我的布局文件时,我得到了 2 个同名文件。我认为这就是发生这种情况的原因。我有 2 个这样的文件:
- activity_score.xml
- activity_score.xml v21 写在名字下。
这是我的 LogCat:
021-09-11 13:33:18.729 3897-3897/com.vishal.kaitka.phodo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.vishal.kaitka.phodo, PID: 3897
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.vishal.kaitka.phodo/com.vishal.kaitka.phodo.Activitys.ScoreActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.vishal.kaitka.phodo.Activitys.ScoreActivity.onCreate(ScoreActivity.java:32)
at android.app.Activity.performCreate(Activity.java:7994)
at android.app.Activity.performCreate(Activity.java:7978)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
在您的问题中,您有 2 个同名文件
1.activity_score.xml
2.activity_score.xmlv21
因此您可以删除 xml 布局并创建新的 activity:
新建 Activity 命名为 Anything You Want
并将所有 xml 代码粘贴到新 Activity 的 xml 布局
所有 java 代码到新 Activity java 文件
我想也许对你有帮助!
我正在 textview 上设置文本,但它给了我 NullPointerException
这是我的 XML 文件。
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activitys.ScoreActivity">
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!--Score Card-->
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_margin="16dp"
app:cardCornerRadius="15dp"
app:cardElevation="6dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="-10dp"
android:text="Your Score"
android:textColor="@color/black"
android:textSize="30sp"
android:textStyle="bold" />
<TextView
android:id="@+id/scoreQTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="60dp"
android:layout_marginBottom="10dp"
android:text="100/200"/>
</androidx.cardview.widget.CardView>
</LinearLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
这是我的 activity 我在 TextView 上设置文本的地方
public class ScoreActivity extends AppCompatActivity {
private TextView scoreQTv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_score);
scoreQTv = findViewById(R.id.scoreQTv);
//and finded all widgets using findviewByID ...
scoreQTv.setText("My Score 18");
}
我无法在我的 TextView 上设置文本。如何设置文本,为什么会出现此错误?
当我检查我的布局文件时,我得到了 2 个同名文件。我认为这就是发生这种情况的原因。我有 2 个这样的文件:
- activity_score.xml
- activity_score.xml v21 写在名字下。
这是我的 LogCat:
021-09-11 13:33:18.729 3897-3897/com.vishal.kaitka.phodo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.vishal.kaitka.phodo, PID: 3897
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.vishal.kaitka.phodo/com.vishal.kaitka.phodo.Activitys.ScoreActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.vishal.kaitka.phodo.Activitys.ScoreActivity.onCreate(ScoreActivity.java:32)
at android.app.Activity.performCreate(Activity.java:7994)
at android.app.Activity.performCreate(Activity.java:7978)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
在您的问题中,您有 2 个同名文件
1.activity_score.xml
2.activity_score.xmlv21
因此您可以删除 xml 布局并创建新的 activity:
新建 Activity 命名为 Anything You Want
并将所有 xml 代码粘贴到新 Activity 的 xml 布局
所有 java 代码到新 Activity java 文件
我想也许对你有帮助!