我希望我的scrollview的可见性设置为我选择了一个导航抽屉页面，我尝试用一些帮助但是得到了nullpointerexecptions并且我得到了错误“无法解析方法setVisibility（int）”和Scrollview无法解决，
MainActivity
package nota.outlawsindex;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;
import org.w3c.dom.Text;
public class MainActivity extends AppCompatActivity {
private String[] mNavigationDrawerItemTitles;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
Toolbar toolbar;
Scrollview scrollView;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
android.support.v7.app.ActionBarDrawerToggle mDrawerToggle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
mNavigationDrawerItemTitles = getResources().getStringArray(R.array.navigation_drawer_items_array);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
setupToolbar();
DataModel[] drawerItem = new DataModel[4];//need to update this if you add start counting at 0
drawerItem[0] = new DataModel(R.drawable.ic_connect, "Calculate Sentence");
drawerItem[1] = new DataModel(R.drawable.ic_fixtures, "Felonies");
drawerItem[2] = new DataModel(R.drawable.ic_table, "Misdemeanors");
drawerItem[3] = new DataModel(R.drawable.ic_drawer, "Infractions");
//add on to the list to create more pages
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
getSupportActionBar().setHomeButtonEnabled(true);
DrawerItemCustomAdapter adapter = new DrawerItemCustomAdapter(this, R.layout.list_view_item_row, drawerItem);
mDrawerList.setAdapter(adapter);
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerLayout.setDrawerListener(mDrawerToggle);
setupDrawerToggle();
}
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
scrollView.setVisibility(View.GONE);
Fragment fragment = null;
switch (position) {
case 0:
fragment = new ConnectFragment();
break;
case 1:
fragment = new FixturesFragment();
break;
case 2:
fragment = new TableFragment();
break;
case 3:
fragment = new SelfAddedFragment();
break;
//add more cases if you add more pages
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(mNavigationDrawerItemTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
Log.e("MainActivity", "Error in creating fragment");
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
//
int id = item.getItemId();
//
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
} else if (id == R.id.action_settings) {
Toast.makeText(getApplicationContext(), "Settings", Toast.LENGTH_SHORT).show();
return true;
}
Toast.makeText(getApplicationContext(), "Search", Toast.LENGTH_SHORT).show();
return super.onOptionsItemSelected(item);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getSupportActionBar().setTitle(mTitle);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
}
void setupToolbar() {
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//getSupportActionBar().setDisplayShowHomeEnabled(true);
}
void setupDrawerToggle() {
mDrawerToggle = new android.support.v7.app.ActionBarDrawerToggle(this, mDrawerLayout, toolbar, R.string.app_name, R.string.app_name);
//This is necessary to change the icon of the Drawer Toggle upon state change.
mDrawerToggle.syncState();
}
}
Activity_Main
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/backgroundColor"
android:visibility="visible">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="@+id/relativeLayout"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<RelativeLayout
android:id="@+id/container_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
</RelativeLayout>
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/container_toolbar"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
</FrameLayout>
<include
android:id="@+id/toolbar"
layout="@layout/toolbar"
android:layout_gravity="right|top"
android:layout_below="@+id/scrollView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="26dp"
android:layout_marginStart="26dp" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/scrollView"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/content_frame"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="@+id/relativeLayout2"
android:focusable="false">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text=" Welcome to The Outlaw's Index! An app designed for individuals who want to educate themselves with knowledge regarding different types of offenses in the United States. Currently this app is directed towards individuals in the United States, but a Canadian version may be released in upcoming months. This app gives users the tools and resources to research different classes of offenses and the repercussions one would receive if convicted. Although this app is informative, advice from law enforcement, attorneys, and other members of the law should be considered more accurate as it may suit your personal needs regarding a specific case. To start off, choose any of the classes on the left hand side, or calculate a sentence and the repercussions that would follow."
android:id="@+id/textView2"
android:textColor="#ffffff"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:password="false"
android:phoneNumber="false"
android:singleLine="false"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="33dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Welcome"
android:id="@+id/textView"
android:textColor="#ffffff"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="27dp"
android:layout_marginStart="27dp" />
</RelativeLayout>
</ScrollView>
</RelativeLayout>
</RelativeLayout>
<ListView
android:id="@+id/left_drawer"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="@color/menuBackgroundColor"
android:choiceMode="singleChoice"
android:divider="@color/colorAccent"
android:dividerHeight="1dp"
android:paddingTop="15dp"/>
<!-- because there is no header in this one I am using android:paddingTop="15dp"
to push the menu below the level of the translucent top bar.-->
这是API 15，也是Android开发的新手
答案 0 :(得分：0)
更改此行：
ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
到这一行：
scrollView = (ScrollView) findViewById(R.id.scrollView);