为什么我的findViewById在这里返回null swipeRefreshLayout = findViewById(R.id.swipeRefreshLayoutDashboard);
?
我已经尝试过使用.getRootView()
并自己进入层次结构,但没有任何成功。你能帮助我吗?
DashboardActivity.java
package eu.niehus.app;
import android.app.AlertDialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import com.github.mikephil.charting.charts.LineChart;
import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.LineData;
import com.github.mikephil.charting.data.LineDataSet;
import com.github.mikephil.charting.utils.EntryXComparator;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
public class DashboardActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private SwipeRefreshLayout swipeRefreshLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DialogFragment fragment = new AddWeightDialog();
fragment.show(getFragmentManager(), "fab");
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
swipeRefreshLayout = findViewById(R.id.swipeRefreshLayoutDashboard);
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
Log.i("onRefreshListener", "refreshing");
update();
}
});
}
}
activity_dashboard.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_dashboard"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_dashboard"
app:menu="@menu/activity_dashboard_drawer" />
</android.support.v4.widget.DrawerLayout>
app_bar_dashboard.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DashboardActivity"
android:id="@+id/constraintLayout">
<android.support.design.widget.AppBarLayout
android:layout_width="0dp"
android:theme="@style/AppTheme.AppBarOverlay"
android:id="@+id/appBarLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay"
/>
</android.support.design.widget.AppBarLayout>
<include
layout="@layout/content_dashboard"
android:layout_height="0dp"
android:layout_width="0dp"
android:id="@+id/include"
app:layout_constraintTop_toBottomOf="@+id/appBarLayout"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
/>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_input_add"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="8dp"/>
</android.support.constraint.ConstraintLayout>
content_dashboard.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/swipeRefreshLayoutDashboard">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<TableLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TableRow
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/tableRowWeighGraph"
android:minHeight="200dp">
<com.github.mikephil.charting.charts.LineChart
android:id="@+id/lineChart"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="999"/>
</TableRow>
</TableLayout>
</ScrollView>
</android.support.v4.widget.SwipeRefreshLayout>
答案 0 :(得分:0)
如果在另一个布局中包含布局,首先需要使用findViewById为其包含的ID创建对象。然后在其上调用findViewById以滑动以刷新布局。
答案 1 :(得分:0)
我已经通过在app_bar_dashboard.xml中的'include'上添加了一个android:id参数来解决它,并使用它来获取我的SwipeRefreshLayout。
以下是更新后的源代码:
DashboardActivity.java:
package eu.niehus.app;
import android.app.AlertDialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.constraint.ConstraintLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import com.github.mikephil.charting.charts.LineChart;
import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.LineData;
import com.github.mikephil.charting.data.LineDataSet;
import com.github.mikephil.charting.utils.EntryXComparator;
import eu.niehus.app.common.DBHelper;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
public class DashboardActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private ConstraintLayout outer;
private SwipeRefreshLayout swipeRefreshLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DialogFragment fragment = new AddWeightDialog();
fragment.show(getFragmentManager(), "fab");
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
dbHelper = new DBHelper(this);
outer = findViewById(R.id.outer);
swipeRefreshLayout = outer.findViewById(R.id.swipeRefreshLayoutInclude);
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
Log.i("onRefreshListener", "refreshing");
update();
}
});
lineChart = swipeRefreshLayout.findViewById(R.id.lineChartWeight);
lineChart.setTouchEnabled(false);
update();
}
}
activity_dashboard.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
android:id="@+id/outer"
layout="@layout/app_bar_dashboard"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_dashboard"
app:menu="@menu/activity_dashboard_drawer" />
</android.support.v4.widget.DrawerLayout>
app_bar_dashboard.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DashboardActivity"
android:id="@+id/constraintLayout">
<android.support.design.widget.AppBarLayout
android:layout_width="0dp"
android:theme="@style/AppTheme.AppBarOverlay"
android:id="@+id/appBarLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay"
/>
</android.support.design.widget.AppBarLayout>
<include
layout="@layout/content_dashboard"
android:layout_height="0dp"
android:layout_width="0dp"
android:id="@+id/swipeRefreshLayoutInclude"
app:layout_constraintTop_toBottomOf="@+id/appBarLayout"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
/>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_input_add"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="8dp"/>
</android.support.constraint.ConstraintLayout>
content_dashboard.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/swipeRefreshLayoutDashboard">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<TableLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TableRow
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/tableRowWeighGraph"
android:minHeight="200dp">
<com.github.mikephil.charting.charts.LineChart
android:id="@+id/lineChartWeight"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="999"/>
</TableRow>
</TableLayout>
</ScrollView>
</android.support.v4.widget.SwipeRefreshLayout>
答案 2 :(得分:0)
尝试演员:swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayoutDashboard);