<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <EditText android:layout_width="fill_parent" android:layout_height="wrap_content" android:textColor="#DDDDDD" android:text="请输入您的名字" android:id ="@+id/et" android:maxLength = "10" ></EditText> <Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="点击转换焦点" ></Button> <EditText android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="点击转换焦点" android:id ="@+id/et2" ></EditText> </LinearLayout>

//表示文本框是否为空 private Boolean isEmpty = true; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); EditText et = (EditText)this.findViewById(R.id.et); //监听控件的焦点改变事件 et.setOnFocusChangeListener(new OnFocusChangeListener() { @Override public void onFocusChange(View arg0, boolean arg1) { // TODO Auto-generated method stub //获取触发事件的EditText EditText clickEditText = (EditText)arg0; //如果失去焦点 if(arg1 == false) { //获取当前文本 String text =clickEditText.getText().toString().trim(); //如果的确人为输入过内容 if(text.length()>0 &text.equals("请输入您的名字")== false) { isEmpty = false; clickEditText.setTextColor(Color.BLACK); clickEditText.setText(text); } else { clickEditText.setText("请输入您的名字"); clickEditText.setTextColor(Color.GRAY); isEmpty = true; } } //如果获得焦点 else { clickEditText.setTextColor(Color.BLACK); //如果处于未编辑状态，则清空“请输入您的名字”这几个字 if(isEmpty == true) { clickEditText.setText(""); } } } }); //监听控件有新字符输入 et.setOnKeyListener(new OnKeyListener() { @Override public boolean onKey(View arg0, int arg1, KeyEvent arg2) { // TODO Auto-generated method stub //获取触发事件的EditText EditText clickEditText = (EditText)arg0; //获取当前文本 String text =clickEditText.getText().toString().trim(); if(text.length()==10) { //提示用户 Toast toast = Toast.makeText(MyActivity.this, "最大长度为10个字符", Toast.LENGTH_SHORT); toast.setGravity(0, 0, 0); toast.show(); } return false; } }); }