Android中监听EditText文本输入

平时在做android开发过程中经常要用到EditText，有时候可能需要监听你在TextView中输入的字数的状态和变化，以便于我们能做相应的提示和操作。我们可以通过下面的方式来实现。

package com.damai.test;


import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


public class TestActivity extends Activity {
    private TextView mTextView;
    private EditText mEditText;
    @Override
    public void onCreate(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 int editStart ;
        private int editEnd ;
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub
temp = s;
}

@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
// mTextView.setText(s);//将输入的内容实时显示
}

@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
            editStart = mEditText.getSelectionStart();
            editEnd = mEditText.getSelectionEnd();
            mTextView.setText("您输入了" + temp.length() + "个字符");
            if (temp.length() > 10) {
                Toast.makeText(TestActivity.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);
            }
}
};
}

 class EditChangedListener implements TextWatcher {        private CharSequence temp;//监听前的文本        private int editStart;//光标开始位置        private int editEnd;//光标结束位置        private final int charMaxNum = 10;        @Override        public void beforeTextChanged(CharSequence s, int start, int count, int after) {            if (DEBUG)                Log.i(TAG, "输入文本之前的状态");            temp = s;        }        @Override        public void onTextChanged(CharSequence s, int start, int before, int count) {            if (DEBUG)                Log.i(TAG, "输入文字中的状态，count是一次性输入字符数");            mTvAvailableCharNum.setText("还能输入" + (charMaxNum - s.length()) + "字符");        }        @Override        public void afterTextChanged(Editable s) {            if (DEBUG)                Log.i(TAG, "输入文字后的状态");            /** 得到光标开始和结束位置 ,超过最大数后记录刚超出的数字索引进行控制 */            editStart = mEditTextMsg.getSelectionStart();            editEnd = mEditTextMsg.getSelectionEnd();            if (temp.length() > charMaxNum) {                Toast.makeText(getApplicationContext(), "你输入的字数已经超过了限制！", Toast.LENGTH_LONG).show();                s.delete(editStart - 1, editEnd);                int tempSelection = editStart;                mEditTextMsg.setText(s);                mEditTextMsg.setSelection(tempSelection);            }        }    };

加上监听的事件。

mEditTextMsg.addTextChangedListener(new EditChangedListener());