按下返回按鈕清除editText的內容

Question

我想清除editText的內容。 當在鍵入時按下后退按鈕時，它應該最小化鍵盤並將我帶回到開始的列表視圖。...現在，它直接存在於該應用程序中。一旦啟動該應用程序，鍵盤就會出現在屏幕上。相反，我希望它在用戶單擊editText時出現。

這是我的代碼：

package com.example.acer.aartisangrah;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;

public class first extends AppCompatActivity {
EditText editText;
private ListView listView;

private String[] names = {"प्रार्थना", "सुखकर्ता दु:खहर्ता", "गजानना श्रीगणराया", "येई हो विठ्ठले", "लवथवती विक्राळा", "दुर्गे दुर्घट भारी", "आरती ज्ञानराजा",
        "हे भोळ्या शंकरा", "ओवाळू", "मंगेशा महारूद्रा", "आला गणराया", "शेंदुर लाल चढायो", "एकदंता", "कर्पूर गौरा", "हे गजवधना", "प्रथमेश्वरा", "जयदेवा हे  साईनाथा",
        "श्री सत्यनारायणाची आरती", "श्री महालक्ष्मीची आरती", "ॐ जय लक्ष्मी माता", "आरती संतोषी माता की", "धन्य धन्य हो प्रदक्षिणा", "सुखंकर्ता की दु:खहर्ता",
        "ॐ जय जगदीश", "हे गौरी गजानन", "घालीन लोटांगण"};
private int imageid[] = {R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji,
        R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji,
        R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji,
        R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji, R.drawable.ganeshaji};
int textlength = 0;
ArrayList<String> text_sort = new ArrayList<String>();

ArrayList<Integer> image_sort = new ArrayList<Integer>();

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_first);
    listView = (ListView) findViewById(R.id.listView);
    editText = (EditText) findViewById(R.id.inputSearch);
    listView.setAdapter(new MyCustomAdapter(names, imageid));
    editText.addTextChangedListener(new TextWatcher()

    {
        public void afterTextChanged(Editable s) {
        }

        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        }

        public void onTextChanged(CharSequence s, int start, int before, int count) {
            textlength = editText.getText().length();
            text_sort.clear();
            image_sort.clear();
            for (int i = 0; i < names.length; i++) {
                if (textlength <= names[i].length()) {
                    if (editText.getText().toString().equalsIgnoreCase((String) names[i].subSequence(0, textlength))) {
                        text_sort.add(names[i]);
                        image_sort.add(imageid[i]);
                    }
                }
            }
            listView.setAdapter(new MyCustomAdapter(text_sort, image_sort));
        }

    });

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            TextView tv = (TextView) view.findViewById(R.id.textViewName);
            String strSelectedString = tv.getText().toString();
            for (int selectedPosition = 0; selectedPosition < names.length; selectedPosition++) {
                if (names[selectedPosition].equalsIgnoreCase(strSelectedString)) {
                    moveToNextActivity(selectedPosition);
                    break;
                }
            }

        }
    });
}


public void moveToNextActivity(int position) {
    if (position == 0) {
        Intent myIntent = new Intent(getApplicationContext(), akalp.class);
        startActivityForResult(myIntent, 0);
    }

    if (position == 1) {
        Intent myIntent = new Intent(getApplicationContext(), Sukharta.class);
        startActivityForResult(myIntent, 0);
    }

    if (position == 2) {
        Intent myIntent = new Intent(getApplicationContext(), gajananashriganraya.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 3) {
        Intent myIntent = new Intent(getApplicationContext(), yehihovittale.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 4) {
        Intent myIntent = new Intent(getApplicationContext(), lavathavthi.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 5) {
        Intent myIntent = new Intent(getApplicationContext(), durgedurgat.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 6) {
        Intent myIntent = new Intent(getApplicationContext(), nyanraja.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 7) {
        Intent myIntent = new Intent(getApplicationContext(), bolya.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 8) {
        Intent myIntent = new Intent(getApplicationContext(), vovalo.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 9) {
        Intent myIntent = new Intent(getApplicationContext(), mangesha.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 10) {
        Intent myIntent = new Intent(getApplicationContext(), alaganraya.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 11) {
        Intent myIntent = new Intent(getApplicationContext(), shendorlal.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 12) {
        Intent myIntent = new Intent(getApplicationContext(), ekdanta.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 13) {
        Intent myIntent = new Intent(getApplicationContext(), karpurgaura.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 14) {
        Intent myIntent = new Intent(getApplicationContext(), heygajavadana.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 15) {
        Intent myIntent = new Intent(getApplicationContext(), prathmeshvara.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 16) {
        Intent myIntent = new Intent(getApplicationContext(), sainatha.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 17) {
        Intent myIntent = new Intent(getApplicationContext(), satyanarayan.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 18) {
        Intent myIntent = new Intent(getApplicationContext(), jaidevijaidevi.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 19) {
        Intent myIntent = new Intent(getApplicationContext(), omjaimahalakshmi.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 20) {
        Intent myIntent = new Intent(getApplicationContext(), maitohaarti.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 21) {
        Intent myIntent = new Intent(getApplicationContext(), danyadanyaho.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 22) {
        Intent myIntent = new Intent(getApplicationContext(), sukhartakidukharta.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 23) {
        Intent myIntent = new Intent(getApplicationContext(), omjaijagdish.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 24) {
        Intent myIntent = new Intent(getApplicationContext(), heygaurigajanana.class);
        startActivityForResult(myIntent, 0);
    }
    if (position == 25) {
        Intent myIntent = new Intent(getApplicationContext(), ghalinlotangan.class);
        startActivityForResult(myIntent, 0);
    }
}

class MyCustomAdapter extends BaseAdapter {
    String[] data_text;
    int[] data_image;

    MyCustomAdapter() {

    }

    MyCustomAdapter(String[] names, int[] imageid) {
        data_text = names;
        data_image = imageid;
    }

    MyCustomAdapter(ArrayList<String> names, ArrayList<Integer> imageid) {
        data_text = new String[names.size()];
        data_image = new int[imageid.size()];
        for (int i = 0; i < names.size(); i++) {
            data_text[i] = names.get(i);
            data_image[i] = imageid.get(i);
        }
    }

    public int getCount() {
        return data_text.length;
    }

    public String getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = getLayoutInflater();
        View row;
        row = inflater.inflate(R.layout.list_layout, parent, false);
        TextView textview = (TextView) row.findViewById(R.id.textViewName);
        ImageView imageview = (ImageView) row.findViewById(R.id.imageView);
        textview.setText(data_text[position]);
        imageview.setImageResource(data_image[position]);
        return (row);
    }
}
}

Answer 1

您將需要在活動中覆蓋onBackPressed（）方法，以使其無法完成

@Override
public void onBackPressed(){
    edittext.setText("");
    listView.setSelection(0);
    //or
    listView.smoothScrollToPosition(0);
}

上面的代碼將edittext設置為一個空字符串，然后在單擊“后退”按鈕時將列表視圖移回索引0。

https://developer.android.com/reference/android/app/Activity.html#onBackPressed（）

編輯

因此，如果您仍處於列表視圖的頂部，為了仍然關閉該應用程序，您將需要添加一些邏輯以跟蹤您在列表視圖中的位置。 最簡單的方法是創建一個在列表視圖滾動偵聽器中更改的布爾值。

public class first extends AppCompatActivity {
EditText editText;
private ListView listView;
boolean atTop; --> add this variable here. This will monitor our top status.
...// rest of logic

然后，我們需要在您的onCreate中將scrollListener應用於您的列表視圖。

listView.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int i) {

            }

            @Override
            public void onScroll(AbsListView absListView, int i, int i1, int i2) {
                if(i == 0){
                    View v = myListView.getChildAt(0);
                    int offset = (v == null) ? 0 : v.getTop();
                    if (offset == 0) {
                        atTop = true;
                        return;
                    }
                }else{
                    atTop = false;
                }
            }
});

本質上，在滾動中，我們正在檢查是否位於頂部或其他位置。 我們不會檢查底部，因此它幾乎可以在任何地方工作。 然后在onBackPressed中，您將執行jsut：

@Override
public void onBackPressed(){
     if(atTop){
          super.onBackPressed();
     }else {
          edittext.setText("");
          listView.setSelection(0);
          //or
          listView.smoothScrollToPosition(0);
      }
}

因此，現在如果我們位於頂部，我們希望onBackPressed能夠正常運行。 如果我們不清除編輯文本，然后滾動到頂部。