Android基础教程：自定义带提示文本的EditText组件

两个类，一个继承Activity的类，一个继承EditText的类，一个xml文件

继承Activity的类：

import Android.app.Activity;
import android.os.Bundle;

public class EditTestActivity extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.edittest);
 }
}

继承EditText的类：

package com.mrzhu.edittest;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.EditText;

public class EditTextTest extends EditText {

public EditTextTest(Context context) {
  super(context);
 }
 
 public EditTextTest(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
 }

public EditTextTest(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

@Override
 protected void onDraw(Canvas canvas) {
  Paint paint = new Paint();
  paint.setTextSize(20);
  paint.setColor(Color.GRAY);
  canvas.drawText("输入提示文本:", 10, getHeight() / 2 + 5, paint);
  super.onDraw(canvas);
 }
}

edittext.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <com.mrzhu.edittest.EditTextTest
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="100dp"
        android:text="从此处输入文本"
        android:id="@+id/test"
        />
</LinearLayout>