package com.example.lab2;import android.os.Bundle;import android.app.Activity;import android.content.Context;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.view.View.OnLongClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ImageButton;import android.widget.LinearLayout;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity {  EditText et1;       //輸入用戶名的EditText  EditText et2;      //輸入密碼的EditText  ImageButton ib;      //聲明ImageButton  Button btn;        //重置按鈕  Context context;  LinearLayout mLinearLayout;      //這個LineatLayout用于放置添加的組件  TextView tv;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    init(); //初始化    //單擊imagebutton    OnClickListener listener = new OnClickListener() {      @Override      public void onClick(View arg0) {        // TODO Auto-generated method stub        if(et1.getText().toString().equals("android") && et2.getText().toString().equals("2015"))        {          ib.setImageResource(R.drawable.state1);  //設置改變原來的圖片          et1.setVisibility(View.GONE);          et2.setVisibility(View.GONE);        }        else   //輸入賬號或者密碼錯誤的時候        {          et2.setText("");          et2.setHint("賬號或密碼錯誤");        }      }    };    ib.setOnClickListener(listener);    //長按imagebutton    OnLongClickListener longlistener = new OnLongClickListener() {      @Override      public boolean onLongClick(View arg0) {        // TODO Auto-generated method stub        Toast.makeText(context, "動態添加了TextView了哦", Toast.LENGTH_SHORT);        tv = new TextView(context);        tv.setText("這里是動態添加的TextView");        mLinearLayout.addView(tv);      //添加組件        return false;      }    };    ib.setOnLongClickListener(longlistener);    //重置    OnClickListener listener2 = new OnClickListener() {      @Override      public void onClick(View arg0) {        // TODO Auto-generated method stub        ib.setImageResource(R.drawable.state2);        et1.setHint("請輸入用戶名");        et2.setHint("請輸入密碼");        et1.setText("");        et2.setText("");        et2.requestFocus(); //將光標定位EditText        et1.setVisibility(View.VISIBLE);        et2.setVisibility(View.VISIBLE);        mLinearLayout.removeAllViews();    //點擊重置按鈕的時候，也將原來添加的組件一起清除      }    };    btn.setOnClickListener(listener2);  }  //初始化函數  public void init()  {    et1 = (EditText)findViewById(R.id.et_username);    et2 = (EditText)findViewById(R.id.et_passward);    ib = (ImageButton)findViewById(R.id.ib);    btn = (Button)findViewById(R.id.btn);    context = MainActivity.this;    mLinearLayout = (LinearLayout)findViewById(R.id.linearLayout);  }}

<LinearLayout 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:orientation="vertical" >  <EditText    android:id="@+id/et_username"    android:hint="請輸入用戶名"    android:layout_width="fill_parent"    android:layout_height="wrap_content"/>   <EditText    android:id="@+id/et_passward"    android:hint="請輸入密碼"    android:inputType="textPassword"    android:layout_width="fill_parent"    android:layout_height="wrap_content"/>   <ImageButton     android:id="@+id/ib"     android:src="@drawable/state2"     android:layout_width="50dp"     android:layout_height="50dp"/>   <Button     android:id="@+id/btn"     android:text="重置"     android:layout_width="wrap_content"     android:layout_height="wrap_content"/>   <LinearLayout     android:id="@+id/linearLayout"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:orientation="vertical">   </LinearLayout></LinearLayout>