保存搜索历史记录

MainActivity.java

public class MainActivity extends AppCompatActivity {


    List ff=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
    }

    private void initView() {
        final EditText editText =findViewById(R.id.edit);
        final CustomWaterFallViewGroup customWaterFallViewGroup = findViewById(R.id.water_fall);
        Button button = findViewById(R.id.btn);  //搜索
        Button button1 = findViewById(R.id.btn_clear);   //清除

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String s = editText.getText().toString();

                WebDao.getInstance(MainActivity.this).add(s);  //点击按钮添加到数据库

                String query = WebDao.getInstance(MainActivity.this).query();  //通过全查方法吐司显示数据库全部内容
                Toast.makeText(MainActivity.this,query,Toast.LENGTH_SHORT).show();
                ff.add(s);
                customWaterFallViewGroup.setData(ff);
            }
        });

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                customWaterFallViewGroup.clearAll();
            }
        });
    }
}

activity_main.xml

CustomWaterFallViewGroup.java

public class CustomWaterFallViewGroup extends LinearLayout{

    List StringList=new ArrayList<>();
    int MAX=20;
    Context mContext;
    WebDao webDao;
    public CustomWaterFallViewGroup(Context context) {
        super(context);
        mContext=context;
        init();
    }


    public CustomWaterFallViewGroup(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mContext=context;
        init();
    }

    private void init() {
        setOrientation(VERTICAL);

        webDao = new WebDao(mContext);
    }

    public void setData(List data) {
        this.StringList=data;

        shouData();
    }

    private void shouData() {


        removeAllViews();

        LinearLayout linearLayout = (LinearLayout) View.inflate(mContext, R.layout.item_water_fall_h, null);
        addView(linearLayout);//首先先存放一个布局
        int len=0;

        for (int i=0;iMAX){  //如果第一条存放已满，接着添加往下添加布局
               linearLayout = (LinearLayout) View.inflate(mContext,R.layout.item_water_fall_h,null);
               addView(linearLayout);
               len=StringList.size();
            }

            View view = View.inflate(mContext, R.layout.item_water_fall, null);
            TextView textView = view.findViewById(R.id.tv_item_water_fall);
            textView.setText(StringList.get(i));
            linearLayout.addView(view);

            LinearLayout.LayoutParams layoutParams = (LayoutParams) view.getLayoutParams(); //设置文本布局间隔
            layoutParams.weight=1;
            view.setLayoutParams(layoutParams);

            final int index=i;

            view.setOnClickListener(new OnClickListener() {  //点击吐司
                @Override
                public void onClick(View view) {

                    Toast.makeText(mContext,StringList.get(index),Toast.LENGTH_SHORT).show();
                }
            });

            view.setOnLongClickListener(new OnLongClickListener() {  //长按历史记录删除
                @Override
                public boolean onLongClick(View view) {

                    String sss=StringList.get(index);   //删除长按数据库内容
                    WebDao.getInstance(mContext).delete(sss);

                    String query = WebDao.getInstance(mContext).query();
                    Toast.makeText(mContext,query,Toast.LENGTH_SHORT).show();

                    StringList.remove(index);  //长按删除单个记录
                    shouData();
                    return true;
                }
            });
        }

    }

    public void clearAll() {  //点击按钮清除全部历史记录
        StringList.clear();
        shouData();

        WebDao.getInstance(mContext).delAll();  //清除数据库内容

        String query = WebDao.getInstance(mContext).query();
        Toast.makeText(mContext,query,Toast.LENGTH_SHORT).show();
    }
}

item_water_fall_h.xml

item_water_fall.xml

WebView.java

public class WebDao {
    MHelper mHelper;
    SQLiteDatabase database;
    ArrayList list;

    public WebDao(Context context) {
        mHelper = new MHelper(context);
        database = mHelper.getReadableDatabase();
    }

    private static WebDao instance;
    public static WebDao getInstance(Context context){
       if (instance==null){
           instance =new WebDao(context);
       }
       return instance;
    }

    public void add(String data){
        //database.execSQL("insert into num(data) values(?)",new Object[]{data});
        ContentValues values=new ContentValues();
        values.put("data",data);
        database.insert("num",null,values);
    }

    public String query(){
        Cursor cursor = database.rawQuery("select * from num", null);

        //list = new ArrayList<>();
        StringBuilder builder = new StringBuilder();
        while (cursor.moveToNext()){
            String data = cursor.getString(cursor.getColumnIndex("data"));
            builder.append(data);
        }

        return builder.toString();
    }

    public void delete(String data){
        database.execSQL("delete from num where data=?",new Object[]{data});
        //database.delete("num","data=?",new String[]{data});
    }

    public void delAll(){
        database.delete("num",null,null);
    }

}

MHelper.java

public class MHelper extends SQLiteOpenHelper{

    public MHelper(Context context) {
        super(context, "bw.db",null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL("create table num (id integer primary key autoincrement,data text)");

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}