Android开发中button按钮的使用及动态添加组件方法示例

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;       //输入用户名的EditText
  EditText et2;      //输入密码的EditText
  ImageButton ib;      //声明ImageButton
  Button btn;        //重置按钮
  Context context;
  LinearLayout mLinearLayout;      //这个LineatLayout用于放置添加的组件
  TextView tv;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    init(); //初始化
    //单击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);  //设置改变原来的图片
          et1.setVisibility(View.GONE);
          et2.setVisibility(View.GONE);
        }
        else   //输入账号或者密码错误的时候
        {
          et2.setText("");
          et2.setHint("账号或密码错误");
        }
      }
    };
    ib.setOnClickListener(listener);
    //长按imagebutton
    OnLongClickListener longlistener = new OnLongClickListener() {
      @Override
      public boolean onLongClick(View arg0) {
        // TODO Auto-generated method stub
        Toast.makeText(context, "动态添加了TextView了哦", Toast.LENGTH_SHORT);
        tv = new TextView(context);
        tv.setText("这里是动态添加的TextView");
        mLinearLayout.addView(tv);      //添加组件
        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("请输入用户名");
        et2.setHint("请输入密码");
        et1.setText("");
        et2.setText("");
        et2.requestFocus(); //将光标定位EditText
        et1.setVisibility(View.VISIBLE);
        et2.setVisibility(View.VISIBLE);
        mLinearLayout.removeAllViews();    //点击重置按钮的时候，也将原来添加的组件一起清除
      }
    };
    btn.setOnClickListener(listener2);
  }
  //初始化函数
  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="请输入用户名"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
   <EditText
    android:id="@+id/et_passward"
    android:hint="请输入密码"
    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>