AutoCompleteTextView 简单设置

新手写给自己看 ，也是上网看别人代码

import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private AutoCompleteTextView autoTv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        autoTv = (AutoCompleteTextView) findViewById(R.id.actv);
        initAutoComplete("history", autoTv);
        Button search = (Button) findViewById(R.id.sousuo);
        search.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // 这里可以设定：当搜索成功时，才执行保存操作
        saveHistory("history", autoTv);
    }


    /**
     * 初始化AutoCompleteTextView，最多显示5项提示，使
     * AutoCompleteTextView在一开始获得焦点时自动提示
     *
     * @param field 保存在sharedPreference中的字段名
     * @param auto  要操作的AutoCompleteTextView
     */
    private void initAutoComplete(String field, AutoCompleteTextView auto) {
        SharedPreferences sp = getSharedPreferences("network_url", 0);
        String longhistory = sp.getString("history", "nothing");
        String[] hisArrays = longhistory.split(",");
        //就是把你所保存的信息 设置成数据源通过适配器的方式
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_dropdown_item_1line, hisArrays);
        //只保留最近的50条的记录
        if (hisArrays.length > 50) {
            String[] newArrays = new String[50];
            System.arraycopy(hisArrays, 0, newArrays, 0, 50);
            adapter = new ArrayAdapter<String>(this,
                    android.R.layout.simple_dropdown_item_1line, newArrays);
        }
        //最主要的就是 跟这个 控件设置adapter
        auto.setAdapter(adapter);
        auto.setDropDownHeight(500);
        auto.setThreshold(1);
        auto.setCompletionHint("最近的5条记录");
        //这个是刚进来 然后  显示 你的历史记录
       /* auto.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                AutoCompleteTextView view = (AutoCompleteTextView) v;
                if (hasFocus) {
                    view.showDropDown();
                }
            }
        });*/
        //这个是你点击了之后 才显示你的 记录
        auto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AutoCompleteTextView view = (AutoCompleteTextView) v;
                view.showDropDown();
            }
        });

    }


    /**
     * 把指定AutoCompleteTextView中内容保存到sharedPreference中指定的字符段
     *
     * @param field 保存在sharedPreference中的字段名
     * @param auto  要操作的AutoCompleteTextView
     */
    private void saveHistory(String field, AutoCompleteTextView auto) {
        String text = auto.getText().toString();
        SharedPreferences sp = getSharedPreferences("network_url", 0);
        String longhistory = sp.getString(field, "nothing");
        if (!longhistory.contains(text + ",")) {
            StringBuilder sb = new StringBuilder(longhistory);
            sb.insert(0, text + ",");
            sp.edit().putString("history", sb.toString()).commit();
        }
    }
}