scroll down from a TextView click to a TextView
Question
hi i want to scroll down automatically to a text view from a text view in the same layout but it gives me error please find out the error where i am doing wrong..here is my code. i want that when i click on the textview of id "Signandsymptoms" it scroll down directly to the id of "Signandsymptomsparagragh".
Error log:
01-28 15:22:39.929: E/AndroidRuntime(18673): FATAL EXCEPTION: main
01-28 15:22:39.929: E/AndroidRuntime(18673): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.kmcpesh.shortreviewofcardiology/com.kmcpesh.shortreviewofcardiology.Atherosclerosis}: java.lang.NullPointerException
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2219)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread.access$700(ActivityThread.java:159)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.os.Handler.dispatchMessage(Handler.java:99)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.os.Looper.loop(Looper.java:137)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread.main(ActivityThread.java:5419)
01-28 15:22:39.929: E/AndroidRuntime(18673): at java.lang.reflect.Method.invokeNative(Native Method)
01-28 15:22:39.929: E/AndroidRuntime(18673): at java.lang.reflect.Method.invoke(Method.java:525)
01-28 15:22:39.929: E/AndroidRuntime(18673): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187)
01-28 15:22:39.929: E/AndroidRuntime(18673): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
01-28 15:22:39.929: E/AndroidRuntime(18673): at dalvik.system.NativeStart.main(Native Method)
01-28 15:22:39.929: E/AndroidRuntime(18673): Caused by: java.lang.NullPointerException
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.Activity.findViewById(Activity.java:1914)
01-28 15:22:39.929: E/AndroidRuntime(18673): at com.kmcpesh.shortreviewofcardiology.Atherosclerosis.<init>(Atherosclerosis.java:24)
E/AndroidRuntime(18673): at java.lang.Class.newInstanceImpl(Native Method)
01-28 15:22:39.929: E/AndroidRuntime(18673): at java.lang.Class.newInstance(Class.java:1130)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.Instrumentation.newActivity(Instrumentation.java:1078)
01-28 15:22:39.929: E/AndroidRuntime(18673): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2210)
.
import android.os.Build;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ScrollView;
import android.widget.TextView;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@SuppressLint("NewApi")
public class Atherosclerosis extends Activity {
ScrollView scrollView=(ScrollView)findViewById(R.id.scrollatherosclerosis);
TextView tv=(TextView)findViewById(R.id.Signandsymptompsid);
TextView tvabove=(TextView)findViewById(R.id.Signandsymptomsparagraph);
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.atherosclerosis);
ActionBar bar = getActionBar();
bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#6B8E23")));
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
scrollView.post(
new Runnable() {
@Override
public void run() {
new CountDownTimer(1500, 20) {
@Override
public void onTick(long millisUntilFinished) {
scrollView.scrollTo(0, (int) (tvabove.getBottom()-millisUntilFinished));
}
@Override
public void onFinish() {
}
}.start();
}
}
);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.atherosclerosis, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Take appropriate action for each action item click
switch (item.getItemId()) {
case R.id.id_search:
Intent newActivity0 = new Intent(this,Search.class);
startActivity(newActivity0);
return true;
case R.id.id_favorit:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
My .XML layout
<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:background="#ffffff"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".Atherosclerosis"
tools:ignore="UselessParent,ScrollViewCount" >
<ScrollView
android:id="@+id/scrollatherosclerosis"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:id="@+id/tablecontentlayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:background="#EFECCB" >
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="17sp"
android:textStyle="bold"
android:textColor="#000000"
android:text="@string/table" />
<TextView
android:id="@+id/definitionid"
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Definition" />
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/RiskFactors" />
<TextView
android:id="@+id/pathophysiology_id"
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Pathophysiology" />
<TextView
android:id="@+id/Signandsymptompsid"
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/SignsandSymptoms" />
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Diagnosis" />
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Treatment" />
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Prevention" />
<TextView
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:textStyle="bold"
android:textColor="#4682B4"
android:text="@string/Complications" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/tablecontentlayout"
android:layout_marginTop="15dp"
android:orientation="vertical" >
<TextView
android:id="@+id/atherodefinition"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Definition"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/atherosclerosisdefinition"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/RiskFactors"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Modifiable"
android:textStyle="bold"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/modifiableatherosclerosis"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Nonmodifiable"
android:textStyle="bold"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/nonmodifiableatherosclerosis"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Pathophysiology"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/pathophysiologyatherosclerosis"
android:textSize="15sp"/>
<TextView
android:id="@+id/Signandsymptomsparagraph"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/SignsandSymptoms"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/atherosclerosissignsandsymptoms"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Diagnosis"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Diagnosisatherosclerosis"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Treatment"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/lifestylemodification"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/treatmentatherosclerosis"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Prevention"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Preventionatherosclerosis"
android:textSize="15sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/Complications"
android:background="#F5F5F5"
android:textColor="#264177"
android:textSize="17sp"
android:textStyle="bold"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/complicationatherosclerosis"
android:textSize="15sp"/>
</LinearLayout>
</RelativeLayout>
</ScrollView>
</RelativeLayout>
1 answers
solution1
0 ACCPTED 2014-01-28 10:47:25
i think your problem solved if you call findViewById() in onCreate() Method like this:
private ScrollView scrollView;
private TextView tvabove;
private TextView tv;
....
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dragpanel);
scrollView = (ScrollView)findViewById(R.id.scrollatherosclerosis);
tv = (TextView)findViewById(R.id.Signandsymptompsid);
tvabove = (TextView)findViewById(R.id.Signandsymptomsparagraph);
...
}
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