安卓天天练练（七）轮播图

也算不上轮播，只是有两个按钮用来刷出上一张和下一张的图片。

先拖元件，新建string

<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.narumi.android_9_1.MainActivity" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="105dp"
        android:layout_height="105dp"
        android:layout_x="100dp"
        android:layout_y="36dp"
        android:src="@drawable/ic_launcher" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="41dp"
        android:layout_y="160dp"
        android:text="@string/prev_btn" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="184dp"
        android:layout_y="160dp"
        android:=""
        android:text="@string/next_btn" />

</AbsoluteLayout>

 写一点Java，新的知识点是针对v对象的判断语句以及求模运算的作用

package com.narumi.android_9_1;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {
    ImageView iv;
    Button btnPrev;
    Button btnNext;
    
 int[] imgId = {
        R.drawable.p01,
        R.drawable.p02,
        R.drawable.p03,
        R.drawable.p04,
        R.drawable.p05,
        R.drawable.p06,
    };
    
    int currImgId = 0;
    
    private View.OnClickListener mylistener = new View.OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if(v == btnPrev){
                currImgId = (currImgId - 1 + imgId.length)%imgId.length;
                iv.setImageResource(imgId[currImgId]);
            }else if(v == btnNext){
                currImgId = (currImgId+1)%imgId.length;
                iv.setImageResource(imgId[currImgId]);
            }
        }
    };
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        iv = (ImageView)findViewById(R.id.imageView1);
        
        btnPrev = (Button)findViewById(R.id.button1);
        
        btnNext = (Button)findViewById(R.id.button2);
        
        btnPrev.setOnClickListener(mylistener);
        
        btnNext.setOnClickListener(mylistener);
    }

}

最原始的无任何动画效果的图片切换就出来了，此例结束。