Android EditText的TextWatcher监听回调参数详解

来源：互联网发布：asp读取excel数据编辑：程序博客网时间：2024/06/05 16:15

先贴代码

        mEditText = (EditText) findViewById(R.id.edittext);        mEditText.addTextChangedListener(new TextWatcher() {            @Override            public void beforeTextChanged(CharSequence s, int start, int count, int after) {                Log.i("CustomActivity","beforeTextChanged");                Log.i("beforeTextChanged","s = " + s);                Log.i("beforeTextChanged","start = " + start);                Log.i("beforeTextChanged","count = " + count);                Log.i("beforeTextChanged","after = " + after);            }            @Override            public void onTextChanged(CharSequence s, int start, int before, int count) {                Log.i("CustomActivity","onTextChanged");                Log.i("onTextChanged","s = " + s);                Log.i("onTextChanged","start = " + start);                Log.i("onTextChanged","count = " + count);                Log.i("onTextChanged","before = " + before);            }            @Override            public void afterTextChanged(Editable s) {                Log.i("CustomActivity","afterTextChanged");                Log.i("afterTextChanged","s = " + s);            }        });

当输入第一个字符”0”的时候,log如下

06-28 20:44:09.815 28820-28820/com.alfred.chowder I/CustomActivity: beforeTextChanged06-28 20:44:09.815 28820-28820/com.alfred.chowder I/beforeTextChanged: s = 06-28 20:44:09.815 28820-28820/com.alfred.chowder I/beforeTextChanged: start = 006-28 20:44:09.815 28820-28820/com.alfred.chowder I/beforeTextChanged: count = 006-28 20:44:09.815 28820-28820/com.alfred.chowder I/beforeTextChanged: after = 106-28 20:44:09.815 28820-28820/com.alfred.chowder I/CustomActivity: onTextChanged06-28 20:44:09.815 28820-28820/com.alfred.chowder I/onTextChanged: s = 006-28 20:44:09.815 28820-28820/com.alfred.chowder I/onTextChanged: start = 006-28 20:44:09.815 28820-28820/com.alfred.chowder I/onTextChanged: count = 106-28 20:44:09.815 28820-28820/com.alfred.chowder I/onTextChanged: before = 006-28 20:44:09.815 28820-28820/com.alfred.chowder I/CustomActivity: afterTextChanged06-28 20:44:09.815 28820-28820/com.alfred.chowder I/afterTextChanged: s = 0

当连续输入两个字符的时候(用搜狗输入法打”你好”,PS:记得连拼),log如下

06-28 20:51:50.415 28820-28820/com.alfred.chowder I/CustomActivity: beforeTextChanged06-28 20:51:50.419 28820-28820/com.alfred.chowder I/beforeTextChanged: s = 006-28 20:51:50.419 28820-28820/com.alfred.chowder I/beforeTextChanged: start = 106-28 20:51:50.419 28820-28820/com.alfred.chowder I/beforeTextChanged: count = 006-28 20:51:50.419 28820-28820/com.alfred.chowder I/beforeTextChanged: after = 206-28 20:51:50.419 28820-28820/com.alfred.chowder I/CustomActivity: onTextChanged06-28 20:51:50.419 28820-28820/com.alfred.chowder I/onTextChanged: s = 0你好06-28 20:51:50.419 28820-28820/com.alfred.chowder I/onTextChanged: start = 106-28 20:51:50.419 28820-28820/com.alfred.chowder I/onTextChanged: count = 206-28 20:51:50.419 28820-28820/com.alfred.chowder I/onTextChanged: before = 006-28 20:51:50.419 28820-28820/com.alfred.chowder I/CustomActivity: afterTextChanged06-28 20:51:50.419 28820-28820/com.alfred.chowder I/afterTextChanged: s = 0你好

分析如下

beforeTextChanged

s : 之前输入的文字
start : 当前输入第一个字符的下标,从0开始
count : 不知道为何一直为0
after : 本次输入的个数(但是看变量名不像啊(⊙o⊙)…)

onTextChanged

s : 当前输入的所有文字(界面展示的文字)
start : 当前输入的第一个字符的下标,从0开始
count : 本次输入的个数
before : 不知道为何一直为0

afterTextChanged

s : 当前输入的所有文字(界面展示的文字) 与onTextChanged参数中的s值是一致的

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