吳裕雄--天生自然ANDROID開發學習:3.5 監聽EditText的內容變化
阿新 • • 發佈:2020-08-29
1.監聽EditText的內容變化 由題可知,是基於監聽的事件處理機制,好像前面的點選事件是OnClickListener,文字內容 變化的監聽器則是:TextWatcher,我們可以呼叫EditText.addTextChangedListener(mTextWatcher); 為EditText設定內容變化監聽! 簡單說下TextWatcher,實現該類需實現三個方法: public void beforeTextChanged(CharSequence s, int start,int count, int after); public void onTextChanged(CharSequence s, int start, int before, int count); public void afterTextChanged(Editable s); 依次會在下述情況中觸發: 1.內容變化前 2.內容變化中 3.內容變化後 我們可以根據實際的需求重寫相關方法,一般重寫得較多的是第三個方法! 監聽EditText內容變化的場合有很多: 限制字數輸入,限制輸入內容等等~ 這裡給大家實現一個簡單的自定義EditText,輸入內容後,有面會顯示一個叉叉的圓圈,使用者點選後 可以清空文字框~,當然你也可以不自定義,直接為EditText新增TextWatcher然後設定下刪除按鈕
自定義EditText:DelEditText.java package demo.com.jay.buttondemo; import android.content.Context; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.text.Editable; import android.text.TextWatcher; import android.util.AttributeSet; import android.view.MotionEvent; import android.widget.EditText; /** * Created by coder-pig on 2015/7/16 0016. */ public class DelEditText extends EditText { private Drawable imgClear; private Context mContext; public DelEditText(Context context, AttributeSet attrs) { super(context, attrs); this.mContext = context; init(); } private void init() { imgClear = mContext.getResources().getDrawable(R.drawable.delete_gray); addTextChangedListener(new TextWatcher() { @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { } @Override public void afterTextChanged(Editable editable) { setDrawable(); } }); } //繪製刪除圖片 private void setDrawable(){ if (length() < 1) setCompoundDrawablesWithIntrinsicBounds(null, null, null, null); else setCompoundDrawablesWithIntrinsicBounds(null, null, imgClear, null); } //當觸控範圍在右側時,觸發刪除方法,隱藏叉叉 @Override public boolean onTouchEvent(MotionEvent event) { if(imgClear != null && event.getAction() == MotionEvent.ACTION_UP) { int eventX = (int) event.getRawX(); int eventY = (int) event.getRawY(); Rect rect = new Rect(); getGlobalVisibleRect(rect); rect.left = rect.right - 100; if (rect.contains(eventX, eventY)) setText(""); } return super.onTouchEvent(event); } @Override protected void finalize() throws Throwable { super.finalize(); } } EditText的背景drawable:bg_frame_search.xml <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" > <solid android:color="@color/background_white" /> <corners android:radius="5dp" /> <stroke android:width="1px" android:color="@color/frame_search"/> </shape> 顏色資源:color.xml <?xml version="1.0" encoding="utf-8"?> <resources> <color name="reveal_color">#FFFFFF</color> <color name="bottom_color">#3086E4</color> <color name="bottom_bg">#40BAF8</color> <color name="frame_search">#ADAEAD</color> <color name="background_white">#FFFFFF</color> <color name="back_red">#e75049</color> </resources> 佈局檔案:activity_main.xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/back_red" android:orientation="vertical" tools:context=".MainActivity"> <demo.com.jay.buttondemo.DelEditText android:id="@+id/edit_search" android:layout_width="match_parent" android:layout_height="32dp" android:layout_margin="10dp" android:background="@drawable/bg_frame_search" android:hint="帶刪除按鈕的EditText~" android:maxLength="20" android:padding="5dp" android:singleLine="true" /> </LinearLayout>
2.實現EditText的密碼可見與不可見 這個也是一個很實用的需求,就是使用者點選按鈕後可讓EditText中的密碼可見或者不可見
實現程式碼: activity_main.xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:layout_margin="5dp" android:orientation="horizontal"> <EditText android:id="@+id/edit_pawd" android:layout_width="0dp" android:layout_weight="2" android:layout_height="48dp" android:inputType="textPassword" android:background="@drawable/editborder"/> <Button android:id="@+id/btnChange" android:layout_width="0dp" android:layout_weight="1" android:layout_height="48dp" android:text="密碼可見"/> </LinearLayout> MainActivity.java package com.jay.demo.edittextdemo; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.text.method.HideReturnsTransformationMethod; import android.text.method.PasswordTransformationMethod; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; public class MainActivity extends AppCompatActivity { private EditText edit_pawd; private Button btnChange; private boolean flag = false; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); edit_pawd = (EditText) findViewById(R.id.edit_pawd); btnChange = (Button) findViewById(R.id.btnChange); edit_pawd.setHorizontallyScrolling(true); //設定EditText不換行 btnChange.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { if(flag == true){ edit_pawd.setTransformationMethod(HideReturnsTransformationMethod.getInstance()); flag = false; btnChange.setText("密碼不可見"); }else{ edit_pawd.setTransformationMethod(PasswordTransformationMethod.getInstance()); flag = true; btnChange.setText("密碼可見"); } } }); } } editborder.xml <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" > <!-- 設定透明背景色 --> <solid android:color="#FFFFFF" /> <!-- 設定一個白色邊框 --> <stroke android:width="1px" android:color="#FFFFFF" /> <!-- 設定一下邊距,讓空間大一點 --> <padding android:bottom="5dp" android:left="5dp" android:right="5dp" android:top="5dp" /> </shape>