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通过TextWatcher监听输入框内容和输入字数限制

布局中EditText在android布局中经常用到,对EditText中输入的内容也经常需要进行限制,我们可以通过TextWatcher去观察输入框中输入的内容,作个笔记。主布局:        java代码:package com.android.t......

布局中EditText在android布局中经常用到,对EditText中输入的内容也经常需要进行限制,我们可以通过TextWatcher去观察输入框中输入的内容,作个笔记。

主布局:

        

java代码:

package com.android.text; import android.app.Activity; import android.os.Bundle; importandroid.text.Editable; import android.text.TextWatcher; import android.util.Log; importandroid.widget.EditText; import android.widget.TextView; import android.widget.Toast;public class TextWatcherDemo extends Activity { private TextView mTextView; privateEditText mEditText; /** Called when the activity is first created. */ @Override public voidonCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.main); mTextView = (TextView)findViewById(R.id.tv); mEditText =(EditText)findViewById(R.id.ET); mEditText.addTextChangedListener(mTextWatcher); } TextWatcher mTextWatcher = new TextWatcher() { private CharSequence temp; private inteditStart ; private int editEnd ; @Override public void beforeTextChanged(CharSequence s,int arg1, int arg2, int arg3) { temp = s; } @Override public voidonTextChanged(CharSequence s, int arg1, int arg2, int arg3) { mTextView.setText(s); } @Override public void afterTextChanged(Editable s) { editStart =mEditText.getSelectionStart(); editEnd = mEditText.getSelectionEnd(); if (temp.length() > 10 ) { Toast.makeText(TextWatcherDemo. this , "你输入的字数已经超过了限制!" , Toast.LENGTH_SHORT) .show(); s.delete(editStart-1 , editEnd); int tempSelection = editStart; mEditText.setText(s); mEditText.setSelection(tempSelection); } } };}