任务1---打招呼

一、运行效果

二、核心代码

1.activity_main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@drawable/bg" >    <EditText        android:id="@+id/etName"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_alignParentTop="true"        android:layout_marginRight="45dp"        android:layout_marginTop="94dp"        android:background="@android:drawable/edit_text"        android:drawableLeft="@drawable/name"        android:ems="10"        android:hint="@string/etNamePrompt" >          <requestFocus />    </EditText>    <Button        android:id="@+id/btnClick"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/etName"        android:layout_below="@+id/etName"        android:layout_marginLeft="70dp"        android:layout_marginTop="30dp"        android:background="@drawable/btn_bg"        android:onClick="hello" /></RelativeLayout>

2.HelloAndroid  Mainfest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="cn.edu.bzu.helloandroid"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="14"        android:targetSdkVersion="19" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity android:name="cn.edu.bzu.helloandroid.MainActivity" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

3.MainActivity.java

package cn.edu.bzu.helloandroid;import android.app.Activity;import android.os.Bundle;import android.view.Gravity;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.RelativeLayout;import android.widget.Toast;public class MainActivity extends Activity {private Button btnClick;private EditText etName;private Toast toast;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);btnClick = (Button) findViewById(R.id.btnClick);btnClick.setOnClickListener(new ClickHandler());etName = (EditText) findViewById(R.id.etName);}class ClickHandler implements OnClickListener {@Overridepublic void onClick(View view) {String name = etName.getText().toString();toast = Toast.makeText(MainActivity.this, "Hello " + name + " !",Toast.LENGTH_LONG);/*toast.setGravity(Gravity.CENTER, 0, 0);RelativeLayout toastView = (RelativeLayout) toast.getView();ImageView imageCodeProject = new ImageView(getApplicationContext());imageCodeProject.setImageResource(R.drawable.smile);toastView.addView(imageCodeProject, 0);*/toast.show();}}}

三、程序出现的问题

1.添加带图片的toast时，加入代码
toast.setGravity(Gravity.CENTER, 0, 0);
RelativeLayout toastView = (RelativeLayout) toast.getView();
ImageView imageCodeProject = new ImageView(getApplicationContext());
imageCodeProject.setImageResource(R.drawable.smile);
toastView.addView(imageCodeProject, 0);

运行时出现错误，程序停止运行，出现主函数致命异常，不加这几行代码程序可正常运行。问题还没有解决，希望老师指点。

2.对于调用方法以及方法中传入参数不能运用的熟练，对基本语法掌握不熟练，运用得先去查资料，写个小程序需要很长时间。