Activity初级：resultCode返回码、 onclick代码重构

主页：

public class MainActivity extends Activity
{
/**
* 主页点击按钮跳转到第二页
* 第二页点击按钮1将字符串内容显示到主页，点击按钮2将数字内容显示到主页
*/
private final static int RESULT_CODE_ONE = 1;
private final static int RESULT_CODE_TWO = 2;
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
TextView textView = (TextView) findViewById(R.id.textView1_main);
String text = null;
switch (resultCode)//判断返回码
{
case RESULT_CODE_ONE:
text = "from按钮1:" + data.getStringExtra("btnone");
break;
case RESULT_CODE_TWO:
int age = data.getIntExtra("btntwo", 0);//0为默认值，当data没有接收到返回的int时，返回这个默认值
text ="from按钮2:"+ String.valueOf(age);
break;
default:
break;
}
textView.setText(text);
}

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

findViewById(R.id.button1_main).setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivityForResult(intent , 0);
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

第二页

public class SecondActivity extends Activity
{
private final static int RESULT_CODE_ONE = 1;
private final static int RESULT_CODE_TWO = 2;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
final Intent data = new Intent();
findViewById(R.id.button1).setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View v)
{
data.putExtra("btnone", "name");
setResult(RESULT_CODE_ONE, data );//设置返回码
finish();
}
});

findViewById(R.id.button2).setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
data.putExtra("btntwo", 12);
setResult(RESULT_CODE_TWO, data );//设置返回码
finish();
}
});

}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.second, menu);
return true;
}
}

第二页按钮事件重构过程一：
1.实现OnClickListener接口
2.重写onClick(View v)
3.findViewById(R.id.button1).setOnClickListener(this)

public class SecondActivity extends Activity implements OnClickListener//实现监听者接口
{
private final static int RESULT_CODE_ONE = 1;
private final static int RESULT_CODE_TWO = 2;

@Override
public void onClick(View v)//重写点击方法
{
Intent data = new Intent();
if(v.getId() == R.id.button1)//判断view的id
{
data.putExtra("btnone", "name");
setResult(RESULT_CODE_ONE, data );
finish();
}
if(v.getId() == R.id.button2)
{
data.putExtra("btntwo", 12);
setResult(RESULT_CODE_TWO, data );
finish();
}
}

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);

findViewById(R.id.button1).setOnClickListener(this);//监听按钮
findViewById(R.id.button2).setOnClickListener(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.second, menu);
return true;
}
}

第二页按钮事件重构过程二：将事件内容以方法代替

public class SecondActivity extends Activity implements OnClickListener//实现监听者接口
{
private final static int RESULT_CODE_ONE = 1;
private final static int RESULT_CODE_TWO = 2;

@Override
public void onClick(View v)//重写点击方法
{
Intent data = new Intent();
if(v.getId() == R.id.button1)//判断view的id
{
//            data.putExtra("btnone", "name");
//            setResult(RESULT_CODE_ONE, data );
//            finish();
sendResult("btnone", "name", RESULT_CODE_ONE);
}
if(v.getId() == R.id.button2)
{
//            data.putExtra("btntwo", 12);
//            setResult(RESULT_CODE_TWO, data );
//            finish();
sendResult("btntwo", Integer.valueOf(12), RESULT_CODE_TWO);
}
}

private void sendResult(String extraKey, Object content, int resultCode)
{
Intent data = new Intent();
if (content instanceof String)
{
data.putExtra(extraKey, (String) content);
}
else if (content instanceof Integer)
{
data.putExtra(extraKey, (Integer) content);
}
setResult(resultCode, data);
finish();
}

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);

findViewById(R.id.button1).setOnClickListener(this);//监听按钮
findViewById(R.id.button2).setOnClickListener(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.second, menu);
return true;
}
}