Navigation
基本操作
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<fragment
android:id="@+id/fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="409dp"
android:layout_height="729dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/my_nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.mynavigation;
import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 要先把xml里的组件名称由androidx.fragment.app.FragmentContainerView改成fragment
NavController controller = Navigation.findNavController(this, R.id.fragment);
NavigationUI.setupActionBarWithNavController(this, controller);
}
@Override
public boolean onSupportNavigateUp() {
NavController controller = Navigation.findNavController(this, R.id.fragment);
return controller.navigateUp();
}
}
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".HomeFragment">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.5" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Home"
android:textSize="34sp"
app:layout_constraintBottom_toTopOf="@+id/guideline2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.8" />
<Button
android:id="@+id/btn_home"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="@+id/guideline2"
app:layout_constraintVertical_bias="0.2" />
</androidx.constraintlayout.widget.ConstraintLayout>
</FrameLayout>
package com.example.mynavigation;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class HomeFragment extends Fragment {
public HomeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home, container, false);
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getView().findViewById(R.id.btn_home).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// 界面跳转
NavController controller = Navigation.findNavController(view);
controller.navigate(R.id.action_homeFragment_to_detailFragment);
}
});
}
}
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".DetailFragment">
<!-- TODO: Update blank fragment layout -->
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.5" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Detail"
android:textSize="34sp"
app:layout_constraintBottom_toTopOf="@+id/guideline3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.8" />
<Button
android:id="@+id/btn_detail"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="@+id/guideline3"
app:layout_constraintVertical_bias="0.2" />
</androidx.constraintlayout.widget.ConstraintLayout>
</FrameLayout>
package com.example.mynavigation;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class DetailFragment extends Fragment {
public DetailFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_detail, container, false);
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getView().findViewById(R.id.btn_detail)
.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.action_detailFragment_to_homeFragment));
}
}
<?xml version="1.0" encoding="utf-8"?>
<navigation 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/my_nav_graph"
app:startDestination="@id/homeFragment">
<fragment
android:id="@+id/detailFragment"
android:name="com.example.mynavigation.DetailFragment"
android:label="Detail"
tools:layout="@layout/fragment_detail">
<action
android:id="@+id/action_detailFragment_to_homeFragment"
app:destination="@id/homeFragment"
app:enterAnim="@android:anim/fade_in" />
</fragment>
<fragment
android:id="@+id/homeFragment"
android:name="com.example.mynavigation.HomeFragment"
android:label="Home"
tools:layout="@layout/fragment_home">
<action
android:id="@+id/action_homeFragment_to_detailFragment"
app:destination="@id/detailFragment"
app:enterAnim="@android:anim/slide_in_left" />
</fragment>
</navigation>
转场传值和动画效果
<?xml version="1.0" encoding="utf-8"?>
<navigation 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/my_nav_graph"
app:startDestination="@id/homeFragment">
<fragment
android:id="@+id/homeFragment"
android:name="com.example.mynavigation2.HomeFragment"
android:label="fragment_home"
tools:layout="@layout/fragment_home" >
<action
android:id="@+id/action_homeFragment_to_detailFragment"
app:destination="@id/detailFragment"
app:enterAnim="@anim/slide_from_left" />
</fragment>
<fragment
android:id="@+id/detailFragment"
android:name="com.example.mynavigation2.DetailFragment"
android:label="fragment_detail"
tools:layout="@layout/fragment_detail" >
<argument
android:name="name"
app:argType="string"
android:defaultValue="haha" />
</fragment>
</navigation>
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<fragment
android:id="@+id/fragmentContainerView"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/my_nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.mynavigation2;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".HomeFragment">
<!-- TODO: Update blank fragment layout -->
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Home"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/edt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:hint="请输入"
android:inputType="textPersonName"
android:minHeight="48dp"
android:text="Name"
app:layout_constraintBottom_toTopOf="@+id/button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.895" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.mynavigation2;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.Toast;
public class HomeFragment extends Fragment {
public HomeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home, container, false);
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getView().findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
EditText editText = getView().findViewById(R.id.edt);
String str = editText.getText().toString();
if (TextUtils.isEmpty(str)){
Toast.makeText(getActivity(), "请输入内容", Toast.LENGTH_SHORT).show();
return;
}
Bundle bundle = new Bundle();
bundle.putString("input", str);
NavController controller = Navigation.findNavController(view);
// 可以传递转场动作的id或者转场目的地的id
controller.navigate(R.id.action_homeFragment_to_detailFragment, bundle);
}
});
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".DetailFragment">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.mynavigation2;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class DetailFragment extends Fragment {
public DetailFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_detail, container, false);
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
TextView textView = getView().findViewById(R.id.textView);
String str = getArguments().getString("name");
String str2 = getArguments().getString("input");
textView.setText(str2);
}
}
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:fromXDelta="-100%"
android:toXDelta="0%"
android:duration="1000"/>
</set>
使用viewmodel和databinding
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
dataBinding{ enabled true}
- 将xml改成databing风格才会自动生成binding类
- nav_graph.xml
<?xml version="1.0" encoding="utf-8"?>
<navigation 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/nav_graph"
app:startDestination="@id/masterFragment2">
<fragment
android:id="@+id/masterFragment2"
android:name="com.example.mynavigation3.MasterFragment"
android:label="fragment_master"
tools:layout="@layout/fragment_master" >
<action
android:id="@+id/action_masterFragment2_to_detailFragment3"
app:destination="@id/detailFragment3" />
</fragment>
<fragment
android:id="@+id/detailFragment3"
android:name="com.example.mynavigation3.DetailFragment"
android:label="fragment_detail"
tools:layout="@layout/fragment_detail" >
<action
android:id="@+id/action_detailFragment3_to_masterFragment2"
app:destination="@id/masterFragment2" />
</fragment>
</navigation>
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<androidx.fragment.app.FragmentContainerView
android:id="@+id/fragmentContainerView"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="409dp"
android:layout_height="729dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.mynavigation3;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<data>
<variable
name="data"
type="com.example.mynavigation3.MyViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MasterFragment">
<TextView
android:id="@+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{String.valueOf(data.number)}"
android:textSize="34sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.358" />
<Button
android:id="@+id/btn_next"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下个页面"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.612" />
<SeekBar
android:id="@+id/seekBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:max="10"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
package com.example.mynavigation3;
import android.os.Bundle;
import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.lifecycle.ViewModelProviders;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SeekBar;
import com.example.mynavigation3.databinding.FragmentMasterBinding;
public class MasterFragment extends Fragment {
public MasterFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
MyViewModel myViewModel;
myViewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class);
FragmentMasterBinding binding;
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_master, container, false);
binding.setData(myViewModel);
binding.setLifecycleOwner(getActivity());
binding.btnNext.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
NavController controller = Navigation.findNavController(view);
controller.navigate(R.id.action_masterFragment2_to_detailFragment3);
}
});
binding.seekBar.setProgress(myViewModel.getNumber().getValue());
binding.seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
myViewModel.getNumber().setValue(i);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
return binding.getRoot();
// return inflater.inflate(R.layout.fragment_master, container, false);
}
}
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<data>
<variable
name="data"
type="com.example.mynavigation3.MyViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DetailFragment">
<TextView
android:id="@+id/tv2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{String.valueOf(data.number)}"
android:textSize="34sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.31" />
<Button
android:id="@+id/btn_add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="+"
android:onClick="@{()->data.add(1)}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.208"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btn_minus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="-"
android:onClick="@{()->data.add(-1)}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.782"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.499" />
<Button
android:id="@+id/btn_previous"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="上个界面"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.501"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.653" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
package com.example.mynavigation3;
import android.os.Bundle;
import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.ViewModelProviders;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.example.mynavigation3.databinding.FragmentDetailBinding;
public class DetailFragment extends Fragment {
public DetailFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
MyViewModel myViewModel;
myViewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class);
FragmentDetailBinding binding;
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_detail, container, false);
binding.setData(myViewModel);
binding.setLifecycleOwner(getActivity());
binding.btnPrevious.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
NavController controller = Navigation.findNavController(view);
controller.navigate(R.id.action_detailFragment3_to_masterFragment2);
}
});
return binding.getRoot();
// return inflater.inflate(R.layout.fragment_detail, container, false);
}
}
package com.example.mynavigation3;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;
public class MyViewModel extends ViewModel {
private MutableLiveData<Integer> number;
public MutableLiveData<Integer> getNumber() {
if (number == null){
number = new MutableLiveData<>();
number.setValue(0);
}
return number;
}
public void add(int n){
if (number.getValue() < 0){
number.setValue(0);
} else {
number.setValue(number.getValue() + n);
}
}
}
