Android控件，EditText应用

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">

    <ImageView        android:id="@+id/image_view"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@drawable/ic_launcher" />

    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="确认"        android:layout_gravity="center"/>

</LinearLayout>

package com.example.uiwidgettest2;

import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.*;

public class edittextActivity extends Activity implements View.OnClickListener{

    private ImageView iv;    private Button btn;

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.edittext);        btn = (Button)findViewById(R.id.button);        iv = (ImageView)findViewById(R.id.image_view);        btn.setOnClickListener(this);    }

    @Override    public void onClick(View v) {        switch (v.getId()){            case R.id.button:                iv.setImageResource(R.drawable.dst);                break;            default:                break;        }    }}