java trim

去掉该字符串首尾的空格、制表符等，一般用于验证用户名、密码输入框。

Android基本(13)——ImageView控件和onKeyDown()方法使用 

2011-11-15 10:32:13|  分类： Android |  标签：imageview  android控件  |字号大中小订阅

 

 

这个小例子是ImageView控件和键盘的事件触发方法onKeyDown的使用

java文件：

package com.zjf.android.controls;

 

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import android.view.KeyEvent;

import android.widget.ImageView;

import android.widget.TextView;

 

public class Activity10 extends Activity {

/** Called when the activity is first created. */

 

private static final String TAG = "TextKeyEvent";

private ImageView firstImage = null;

private TextView firstText = null;

private int text;

 

@Override

public void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  setContentView(R.layout.main);

  firstImage = (ImageView) findViewById(R.id.firstImage);

  firstText = (TextView) findViewById(R.id.firstText);

  text = 100;

  firstImage.setAlpha(text);

  firstText.setText("Alpha = " + text * 100 / 0xff + "%");

}

 

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

  Log.v(TAG, "onKeyDown: keyCode = " + keyCode);

  Log.v(TAG, "onKeyDown: String = " + event.toString());

  switch (keyCode) {

  case KeyEvent.KEYCODE_DPAD_UP:

  case KeyEvent.KEYCODE_DPAD_RIGHT:

   text += 20;

   break;

  case KeyEvent.KEYCODE_DPAD_DOWN:

  case KeyEvent.KEYCODE_DPAD_LEFT:

   text -= 20;

   break;

  default:

   break;

  }

  if(text >= 0xFF)

   text = 0xFF;

  if(text <= 0x0)

   text = 0x0;

  firstImage.setAlpha(text);

  firstText.setTag("Alpha = "+text * 100 / 0xff + "%");

  return super.onKeyDown(keyCode, event);

}

 

}

main.xml文件

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

 

    <TextView

        android:id="@+id/firstText"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:gravity="center" />

    <ImageView

        android:id="@+id/firstImage"

        android:src="@drawable/ic_launcher"

        android:layout_gravity="center"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"/>

 

</LinearLayout>