android studying

DoDos Blog

1、按键改变背景颜色
//MainActivity.java
 
package com.xiaod.hello;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import android.widget.Button;

public class MainActivity extends Activity {
@Override

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    final TextView tvHello = (TextView) findViewById(R.id.tvHello);
   
    Button btnRed = (Button) findViewById(R.id.btnRed);
    Button btnGreen = (Button) findViewById(R.id.btnGreen);
   
    btnRed.setOnClickListener(new OnClickListener() {
     public void onClick(View view) {
      tvHello.setText("click");
      tvHello.setBackgroundColor(Color.RED);
     }
    });
 
    btnGreen.setOnClickListener(new OnClickListener() {
     public void onClick(View view) {
      tvHello.setText("click");
      tvHello.setBackgroundColor(Color.GREEN);
     }
    });
}
}
//main.xml
 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:orientation="vertical">
    <TextView android:text="TextView"
     android:id="@+id/textAlphaValue"
     android:layout_height="wrap_content"
     android:layout_width="match_parent">
    </TextView>
    <ImageView android:id="@+id/image"
     android:src="@drawable/laopo"
     android:layout_height="wrap_content"
     android:layout_width="match_parent">
    </ImageView>
</LinearLayout>
 
 
 

 
2、上下左右按键改变图片透明度
//main.java
 
 
package com.xiaod.keyevent;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.ImageView;
import android.widget.TextView;

public class Main extends Activity {
    /** Called when the activity is first created. */
 private TextView mAlphaValueText;
 private int mAlaphaValue;
 private ImageView mImage;
 private static final String TAG = "KeyEvent";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        mAlphaValueText = (TextView) findViewById(R.id.textAlphaValue);
        mAlaphaValue = 900;
        mImage = (ImageView) findViewById(R.id.image);
        mImage.setAlpha(mAlaphaValue);