State mode design procedure: Heroes in the game can rest, defend, attack normally and attack skills according to different physical strength values.

One ． Application scenarios and case descriptions

We often play games in our spare time to relax our body and mind , relieve stress . In many games, heroes have different physical strength values , You can make different actions to face the enemy .

Heroes can rest 、 defense 、 Common attack 、 Skill attack . The physical strength value consumed or recovered is different , for example ：

• rest ： Restore physical strength to the maximum , There is no need to rest when the physical strength is the maximum ;
• defense ： Consume 10 Some physical strength , You can't defend without physical strength ;
• Common attack ： Consume 15 Some physical strength , You can't attack normally without physical strength ;
• Skill attack ： Consume 20 Some physical strength , You can't attack skills without physical strength ;

Two ． Case analysis and problem solving

If we write these operation logic in the same class —— The method of being a hero in the hero class , There will be the following problems ：

1. Later, if the operation logic （ Such as the change of physical strength value consumed ） If there is any change, you need to modify the whole hero class ;
2. If you want to add operations later （ Such as increasing magic attack ） You need to modify the whole hero class ;
3. Only a lot of if—else if—else, The code is not easy to maintain , Poor readability ;

So I decided to use state mode to solve this problem . The advantages of state mode in this scenario ：

1. Using a class to encapsulate a state of an object （ operation ）, It's easy to add new States （ operation ）;
2. In state mode , Environmental Science （Context）—— Heroes （Hero） You don't have to have a lot of conditional statements in . Environmental Science （Context） The state of the instance becomes clearer 、 Easy to understand ;
3. Using state mode allows user programs to easily switch environments （Context）—— Heroes （Hero） Status of the instance （ operation ）;
4. Using state mode doesn't make the environment （Context）—— Heroes （Hero） Internal state inconsistency occurs in the instance of ;
5. When the state object has no instance variables , Environmental Science （Context）—— Heroes （Hero） Each instance of can share a state object ;

I abstract the operation of heroes into states , The four operations correspond to four different specific states ：

• RestState（ Resting state ）
• DefenseState（ Defensive state ）
• NormalAttackState（ Normal attack status ）
• SkillAttackState（ Skill attack status ）

3、 ... and ． Description of each role and UML Icon

Role description ：

1. Environmental Science （Context）：Hero class
2. Abstract state （State）：State abstract class
3. Specific state （Concrete State）：RestState、DefenseState、NormalAttackState and SkillAttackState class

UML chart ：

Four . Running effect

1. Generated apk

1. Icon after installation

1. Running results

   1. Take a rest ：

      

   2. Defend ：

      

   3. Common attack ：

      

   4. Skill attack ：

      

5、 ... and ． Program complete source code

1. Environmental Science （CONTEXT）

In this design , The environmental role is Hero class , The code is as follows ：

Hero.java

package com.yuebanquan.statepattern;

import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import pl.droidsonroids.gif.GifImageView;

public class Hero extends AppCompatActivity implements View.OnClickListener {
    State state;        // current state 
    State lastState;    // Last state 
    private State restState;    // Resting state 
    private State defenseState; // Defensive state 
    private State normalAttackState;    // Normal attack status 
    private State skillAttackState;     // Skill attack status 

    private int MP;     // Hero's physical strength 
    int MAXMP = 100;    // Maximum physical strength 
    int MINMP = 0;      // Minimum physical strength 

    // Declare the components of the interface 
    TextView t_MP;
    TextView t_state;
    Button b_rest;
    Button b_defense;
    Button b_normalAttack;
    Button b_skillAttack;
    GifImageView doingGif;

    // Make a statement Toast
    ToastShow toast = new ToastShow(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        init(MAXMP);

    }

    /*************
     *  initialization Hero
     *************/
    public void init(int MP) {
        this.MP = MP;

        // Initialize various states 
        restState = new RestState(this);
        defenseState = new DefenseState(this);
        normalAttackState = new NormalAttackState(this);
        skillAttackState = new SkillAttackState(this);

        // Heroes default to rest 
        state = restState;
        lastState = restState;

        // Binding interface components 
        t_MP = (TextView) findViewById(R.id.t_MP);
        t_state = (TextView) findViewById(R.id.t_state);
        b_rest = (Button) findViewById(R.id.b_rest);
        b_defense = (Button) findViewById(R.id.b_defense);
        b_normalAttack = (Button) findViewById(R.id.b_normalAttack);
        b_skillAttack = (Button) findViewById(R.id.b_skillAttack);
        doingGif = (GifImageView) findViewById(R.id.doingGif);
http://www.biyezuopin.vip
        // Set listeners for a few buttons 
        b_rest.setOnClickListener(this);
        b_defense.setOnClickListener(this);
        b_normalAttack.setOnClickListener(this);
        b_skillAttack.setOnClickListener(this);
    }


    // Monitor 
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.b_rest:
                setLastState(getState());
                setState(getRestState());
                state.toDo();
                break;
            case R.id.b_defense:
                setLastState(getState());
                setState(getDefenseState());
                state.toDo();
                break;
            case R.id.b_normalAttack:
                setLastState(getState());
                setState(getNormalAttackState());
                state.toDo();
                break;
            case R.id.b_skillAttack:
                setLastState(getState());
                setState(getSkillAttackState());
                state.toDo();
                break;
        }
    }

    void midToast(String str, int showTime) {
        Toast toast = Toast.makeText(Hero.this, str, showTime);
        TextView v = (TextView) toast.getView().findViewById(android.R.id.message);
        toast.show();
    }


    // Various getter and setter
    public int getMP() {
        return MP;
    }

    public void setMP(int MP) {
        this.MP = MP;http://www.biyezuopin.vip
        t_MP.setText(String.valueOf(getMP()));
    }

    public void setState(State state) {
        this.state = state;
    }

    public State getState() {
        return state;
    }

    public State getLastState() {
        return lastState;
    }

    public void setLastState(State lastState) {
        this.lastState = lastState;
    }

    public State getRestState() {
        return restState;
    }

    public State getDefenseState() {
        return defenseState;
    }

    public State getNormalAttackState() {
        return normalAttackState;
    }

    public State getSkillAttackState() {
        return skillAttackState;
    }
}

2. Abstract state （STATE）

For this question , Abstract state （State） yes State abstract class , The code is as follows ：

State.java

package com.yuebanquan.statepattern;

public abstract class State {
    public abstract void toDo();
}

3. Specific state （Concrete State）

For this question , share 4 Specific status roles , Namely RestState、DefenseState、NormalAttackState and SkillAttackState class , The code is as follows ：

RestState.java

package com.yuebanquan.statepattern;

import android.widget.Toast;

public class RestState extends State {
    Hero hero;

    RestState(Hero hero) {
        this.hero = hero;
    }

    public void toDo() {
        if (hero.getMP() == hero.MAXMP) { // Physical strength is full 
            //hero.midToast(" Physical strength is full , No need to rest ", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Physical strength is full , No need to rest ");
            hero.setState(hero.getLastState());
        } 
        else { // Enter a resting state 
            hero.setMP(hero.MAXMP); // Physical strength is set to the maximum 100
            hero.setState(hero.getRestState());
            hero.t_state.setText(" Resting state ");
            hero.doingGif.setImageResource(R.drawable.rest);
            //hero.midToast(" Take a rest , Physical strength has reached the upper limit ", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Take a rest , Physical strength has reached the upper limit ");
        }
    }
}

DefenseState.java

package com.yuebanquan.statepattern;

import android.widget.Toast;

public class DefenseState extends State {
    Hero hero;

    DefenseState(Hero hero) {
        this.hero = hero;
    }

    public void toDo() {
        if (hero.getMP() < (hero.MINMP + 10)) { // Physical strength is not enough 
            //hero.midToast(" Physical strength is not enough , No defense ", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Physical strength is not enough , No defense ");
            hero.setState(hero.getLastState());
        } http://www.biyezuopin.vip
        else {  // Enter a defensive state 
            hero.setMP(hero.getMP() - 10); // Defense physical strength -10
            hero.setState(hero.getDefenseState());
            hero.t_state.setText(" Defensive state ");
            hero.doingGif.setImageResource(R.drawable.defense);
            //hero.midToast(" Defend , Physical strength -10", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Defend , Physical strength -10");
        }
    }
}

NormalAttackState.java

package com.yuebanquan.statepattern;

import android.widget.Toast;

public class NormalAttackState extends State {
    Hero hero;

    NormalAttackState(Hero hero) {
        this.hero = hero;
    }

    public void toDo() {
        if (hero.getMP() < (hero.MINMP + 15)) { // Physical strength is not enough 
            //hero.midToast(" Physical strength is not enough , Cannot attack normally ", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Physical strength is not enough , Cannot attack normally ");
            hero.setState(hero.getLastState());
        } else {  // Enter the normal attack state 
            hero.setMP(hero.getMP() - 15); // Normal attack stamina -15
            hero.setState(hero.getNormalAttackState());
            hero.t_state.setText(" Normal attack status ");
            hero.doingGif.setImageResource(R.drawable.normal_attack);
            //hero.midToast(" Launch a normal attack , Physical strength -15", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Launch a normal attack , Physical strength -15");
        }
    }
}

SkillAttackState.java

package com.yuebanquan.statepattern;

import android.widget.Toast;

public class SkillAttackState extends State {
    Hero hero;

    SkillAttackState(Hero hero) {
        this.hero = hero;
    }

    public void toDo() {
        if (hero.getMP() < (hero.MINMP + 20)) { // Physical strength is not enough 
            //hero.midToast(" Physical strength is not enough , Unable to attack skills ", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Physical strength is not enough , Unable to attack skills ");
            hero.setState(hero.getLastState());
        }
        else {  // Enter the skill attack state 
            hero.setMP(hero.getMP() - 20); // Skill attack physical strength -20
            hero.setState(hero.getSkillAttackState());
            hero.t_state.setText(" Skill attack status ");
            hero.doingGif.setImageResource(R.drawable.skill_attack);
            //hero.midToast(" Launch skill attack , Physical strength -20", Toast.LENGTH_SHORT);
            hero.toast.toastShow(" Launch skill attack , Physical strength -20");
        }
    }
}

4. Other categories

Expand one ToastShow Class to solve Android Self contained Toast Show delay issues , The code is as follows ：

Toast.java

package com.yuebanquan.statepattern;

import android.content.Context;
import android.widget.Toast;

public class ToastShow {
    private Context context;  // Prompt information in this window 

    private Toast toast = null;  // It is used to judge whether there is Toast perform 
    public ToastShow(Context context) {
        this.context = context;
    }
    public void toastShow(String text) {
        if(toast == null)
        {
            toast = Toast.makeText(context, text, Toast.LENGTH_SHORT);  // Normal execution 
        }
        else {
            toast.setText(text);  // Used to overwrite the prompt information that has not disappeared before 
        }
        toast.show();
    }
}

5. Android Layout file for

The layout file is located in app/src/main/res/layout, The code is as follows ：

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".Hero">

    <!-- placeholder -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="100dp" />

    <!-- Hero name -->
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Hero name ："
            android:textSize="30sp"/>

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Moon Spring "
            android:textSize="30sp"/>
    </LinearLayout>

    <!-- Physical strength -->
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Physical strength ："
            android:textSize="30sp"/>

        <TextView
            android:id="@+id/t_MP"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="100"
            android:textSize="30sp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="/100"
            android:textSize="30sp"/>
    </LinearLayout>

    <!-- state -->
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" state ："
            android:textSize="30sp"/>

        <TextView
            android:id="@+id/t_state"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Resting state "
            android:textSize="30sp"/>
    </LinearLayout>

    <!--&lt;!&ndash; placeholder &ndash;&gt;-->
    <!--<TextView-->
        <!--android:layout_width="match_parent"-->
        <!--android:layout_height="100dp" />-->

    <pl.droidsonroids.gif.GifImageView
        android:id="@+id/doingGif"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_gravity="center"
        android:src="@drawable/rest"/>

    <Button
        android:id="@+id/b_rest"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text=" Take a rest "
        android:textSize="30sp" />

    <Button
        android:id="@+id/b_defense"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text=" Defend "
        android:textSize="30sp"/>

    <Button
        android:id="@+id/b_normalAttack"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text=" Common attack "
        android:textSize="30sp"/>

    <Button
        android:id="@+id/b_skillAttack"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text=" Skill attack "
        android:textSize="30sp"/>

</LinearLayout>

6. Android Program declaration file

The program declaration file is located at app/src/, The code is as follows ：

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.yuebanquan.statepattern">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Hero">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

7. Android Of build.gradle

Position in app/, Specify the generated apk Name and introduced module , The code is as follows ：

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.yuebanquan.statepattern"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        vectorDrawables.useSupportLibrary = true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

android.applicationVariants.all {
    variant ->
        variant.outputs.all {
            //  Specify generated here apk file name 
            outputFileName = " Big homework ( The state pattern ).apk"
        }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support:support-vector-drawable:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    // Show GifView modular 
    implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.7'
}