第一行代码

详解build.gradle文件

（gradle是一种项目构建工具）

外层
1.jcenter （）代码托管库
1. depencies 闭包里是一个插件声明
内层
插件编译sdk版本包名最低兼容版本目标版本(做过充分测试）项目版本号版本名
是否对项目进行混淆混淆文件
依赖关系本地依赖远程依赖 jcenter库依赖

打印工具
Log是一个类
Log.v() d i w e

tag 写入一般写类名（对打印信息进行过滤）
msg 具体内容
运行：shift+F10
快捷键 log w d i
logt tag常量
过滤器自定义
日志的级别控制

activity

新建一个活动
1.活动布局
2.加载布局
创建布局的时候会默认根元素
资源文件添加了以后会在R文件下有个id
3.注册活动设置活动为主活动

设置监听器
在活动中使用Toast
Toast.makeText().show

 Button button=(Button)findViewById(R.id.button_1);
        button.setOnClickListener(
        new View.OnClickListener(){
              @Override
               public void onClick(View v){
              Toast.makeText(MyFirstActivity.this,
"you click",Toast.LENGTH_SHORT).show();

创建菜单
menu文件夹资源文件
建立布局文件
重写 onCreatOptionsMenu()方法
活动跳转
intent显式和隐式跳转
打电话用浏览器
活动之间传递数据
ctrl+o 重写
看一下对话主题的错误
控件的使用
布局

 AlertDialog.Builder dialog = new AlertDialog.Builder(HelloWorldActivity.this);
                dialog.setTitle("biaoti");
                dialog.setMessage("xingxi");
                dialog.setCancelable(false);

                dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                dialog.show();

            }
        });

20180831114828.png

20180831114841.png

listview

package com.example.listviewtest;

public class Fruit {

    private String name;

    private int imageId;

    public Fruit(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    public int getImageId() {
        return imageId;
    }

}

package com.example.listviewtest;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

public class FruitAdapter extends ArrayAdapter<Fruit> {

    private int resourceId;

    public FruitAdapter(Context context, int textViewResourceId,
                        List<Fruit> objects) {
        super(context, textViewResourceId, objects);
        resourceId = textViewResourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position); // 获取当前项的Fruit实例
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = (ImageView) view.findViewById (R.id.fruit_image);
            viewHolder.fruitName = (TextView) view.findViewById (R.id.fruit_name);
            view.setTag(viewHolder); // 将ViewHolder存储在View中
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag(); // 重新获取ViewHolder
        }
        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;
    }

    class ViewHolder {

        ImageView fruitImage;

        TextView fruitName;

    }

}

package com.example.listviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<Fruit>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits(); // 初始化水果数据
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        ListView listView = (ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                Fruit fruit = fruitList.get(position);
                Toast.makeText(MainActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void initFruits() {
        for (int i = 0; i < 2; i++) {
            Fruit apple = new Fruit("Apple", R.drawable.apple_pic);
            fruitList.add(apple);
            Fruit banana = new Fruit("Banana", R.drawable.banana_pic);
            fruitList.add(banana);
            Fruit orange = new Fruit("Orange", R.drawable.orange_pic);
            fruitList.add(orange);
            Fruit watermelon = new Fruit("Watermelon", R.drawable.watermelon_pic);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear", R.drawable.pear_pic);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape", R.drawable.grape_pic);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple", R.drawable.pineapple_pic);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit("Strawberry", R.drawable.strawberry_pic);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit("Cherry", R.drawable.cherry_pic);
            fruitList.add(cherry);
            Fruit mango = new Fruit("Mango", R.drawable.mango_pic);
            fruitList.add(mango);
        }
    }

}

recyclerview

package com.example.myrecyclerview;

public class Fruit {

        private String name;

        private int imageId;

        public Fruit(String name, int imageId) {
            this.name = name;
            this.imageId = imageId;
        }

        public String getName() {
            return name;
        }

        public int getImageId() {
            return imageId;
        }

    }

package com.example.myrecyclerview;

import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;


public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
    private List<Fruit> mfruitList;

    static class ViewHolder extends RecyclerView.ViewHolder {//内部类
        ImageView fruitImage;
        TextView fruitName;

        //
        public ViewHolder(View view) {//子项最外层布局
            super(view);//实例化布局
            fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
            fruitName = (TextView) view.findViewById(R.id.fruit_name);

        }
    }

    public FruitAdapter(List<Fruit> fruitList) {//传入数据源 赋值给全局变量
        mfruitList = fruitList;
    }

    //继承3个方法的重写
    @NonNull//创建方法实例化Viewholder 加载子项布局
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from((parent.getContext())).inflate(R.layout.fruit_item, parent, false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }
   // 子项赋值
    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Fruit fruit = mfruitList.get(position);
        holder.fruitImage.setImageResource(fruit.getImageId());
        holder.fruitName.setText(fruit.getName());
    }

    @Override
    public int getItemCount() {
        return mfruitList.size();
    }
}

package com.example.myrecyclerview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

import com.example.*;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    private List<Fruit> fruitList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        //指定布局方式
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
        Log.i(TAG, "onCreate: " );

    }

    private void initFruits() {
        for (int i = 0; i < 2; i++) {
            Fruit apple = new Fruit("Apple", R.drawable.apple_pic);
            fruitList.add(apple);
            Fruit banana = new Fruit("Banana", R.drawable.banana_pic);
            fruitList.add(banana);
            Fruit orange = new Fruit("Orange", R.drawable.orange_pic);
            fruitList.add(orange);
            Fruit watermelon = new Fruit("Watermelon", R.drawable.watermelon_pic);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear", R.drawable.pear_pic);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape", R.drawable.grape_pic);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple", R.drawable.pineapple_pic);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit("Strawberry", R.drawable.strawberry_pic);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit("Strawberry", R.drawable.cherry_pic);
            fruitList.add(cherry);
            Fruit mango = new Fruit("Mango", R.drawable.mango_pic);
            fruitList.add(mango);
        }
    }
}

UI最佳实践

package com.example.uibestpractice;

public class Msg {

    public static final int TYPE_RECEIVED = 0;

    public static final int TYPE_SENT = 1;

    private String content;

    private int type;

    public Msg(String content, int type) {
        this.content = content;
        this.type = type;
    }

    public String getContent() {
        return content;
    }

    public int getType() {
        return type;
    }

}

package com.example.uibestpractice;

import android.app.Activity;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.util.List;

public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder> {

    private List<Msg> mMsgList;

    static class ViewHolder extends RecyclerView.ViewHolder {

        LinearLayout leftLayout;

        LinearLayout rightLayout;

        TextView leftMsg;

        TextView rightMsg;

        public ViewHolder(View view) {
            super(view);
            leftLayout = (LinearLayout) view.findViewById(R.id.left_layout);
            rightLayout = (LinearLayout) view.findViewById(R.id.right_layout);
            leftMsg = (TextView) view.findViewById(R.id.left_msg);
            rightMsg = (TextView) view.findViewById(R.id.right_msg);
        }
    }

    public MsgAdapter(List<Msg> msgList) {
        mMsgList = msgList;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.msg_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Msg msg = mMsgList.get(position);
        if (msg.getType() == Msg.TYPE_RECEIVED) {
            // 如果是收到的消息，则显示左边的消息布局，将右边的消息布局隐藏
            holder.leftLayout.setVisibility(View.VISIBLE);
            holder.rightLayout.setVisibility(View.GONE);
            holder.leftMsg.setText(msg.getContent());
        } else if (msg.getType() == Msg.TYPE_SENT) {
            // 如果是发出的消息，则显示右边的消息布局，将左边的消息布局隐藏
            holder.rightLayout.setVisibility(View.VISIBLE);
            holder.leftLayout.setVisibility(View.GONE);
            holder.rightMsg.setText(msg.getContent());
        }
    }

    @Override
    public int getItemCount() {
        return mMsgList.size();
    }

}

package com.example.uibestpractice;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<Msg> msgList = new ArrayList<Msg>();

    private EditText inputText;

    private Button send;

    private RecyclerView msgRecyclerView;

    private MsgAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initMsgs(); // 初始化消息数据
        inputText = (EditText) findViewById(R.id.input_text);
        send = (Button) findViewById(R.id.send);
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);
        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);
        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String content = inputText.getText().toString();
                if (!"".equals(content)) {
                    Msg msg = new Msg(content, Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyItemInserted(msgList.size() - 1); // 当有新消息时，刷新ListView中的显示
                    msgRecyclerView.scrollToPosition(msgList.size() - 1); // 将ListView定位到最后一行
                    inputText.setText(""); // 清空输入框中的内容
                }
            }
        });
    }

    private void initMsgs() {
        Msg msg1 = new Msg("Hello guy.", Msg.TYPE_RECEIVED);
        msgList.add(msg1);
        Msg msg2 = new Msg("Hello. Who is that?", Msg.TYPE_SENT);
        msgList.add(msg2);
        Msg msg3 = new Msg("This is Tom. Nice talking to you. ", Msg.TYPE_RECEIVED);
        msgList.add(msg3);
    }

}

聊天界面

fragment

package com.example.fragmenttest;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class LeftFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.left_fragment, container, false);
        return view;
    }

}

package com.example.fragmenttest;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class RightFragment extends Fragment {

    public static final String TAG = "RightFragment";

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        Log.d(TAG, "onAttach");
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate");
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        Log.d(TAG, "onCreateView");
        View view = inflater.inflate(R.layout.right_fragment, container, false);
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        Log.d(TAG, "onActivityCreated");
    }

    @Override
    public void onStart() {
        super.onStart();
        Log.d(TAG, "onStart");
    }

    @Override
    public void onResume() {
        super.onResume();
        Log.d(TAG, "onResume");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.d(TAG, "onPause");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.d(TAG, "onStop");
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        Log.d(TAG, "onDestroyView");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.d(TAG, "onDestroy");
    }

    @Override
    public void onDetach() {
        super.onDetach();
        Log.d(TAG, "onDetach");
    }

}

package com.example.fragmenttest;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class AnotherRightFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.another_right_fragment, container, false);
        return view;
    }

}

package com.example.fragmenttest;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(this);
//        replaceFragment(new RightFragment());
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
//                replaceFragment(new AnotherRightFragment());
                break;
            default:
                break;
        }
    }

//    private void replaceFragment(Fragment fragment) {
//        FragmentManager fragmentManager = getSupportFragmentManager();
//        FragmentTransaction transaction = fragmentManager.beginTransaction();
//        transaction.replace(R.id.right_layout, fragment);
//        transaction.addToBackStack(null);
//        transaction.commit();
//    }

}

动态添加碎片
数据库事务（简称：事务）是数据库管理系统执行过程中的一个逻辑单位，由一个有限的数据库操作序列构成。
将碎片添加到返回栈
碎片和活动之间的通信
限定符

coolweather

有个xml文件放错
push 不上

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