Activity初级：startActivityForResult、重写onActivityResult、setResult回传数据、requestCode请求码

/**
* 实现：主页面点击按钮1，跳转到页面二输入内容，点击页面二按钮返回主页面并显示输入信息；
*     主页面点击按钮2，跳转到页面三输入内容，点击页面三按钮返回主页面并显示输入信息.
* 主要步骤：
* 1) startActivityForResult(intent, 0);
* 2) 回传数据时，调用setResult(0, data)方法，然后执行finish()
* 3) onActivityResult(int, int, Intent data)
*/
public class MainActivity extends Activity
{
private static final int BTN_ONE = 1;//将常量封装定义
private static final int BTN_TWO = 2;

@Override//重写onActivityResult
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);//有参数的super必须重写
TextView textView = (TextView) findViewById(R.id.textView1_main);

if(requestCode == BTN_ONE)//根据请求码判断接收内容
{
String str = data.getStringExtra("one");
textView.setText(str);
}
else if(requestCode == BTN_TWO)
{
String str = data.getStringExtra("two");
textView.setText(str);
}

}

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

//监听button1，跳转到NextActivity，等待result
Button button1=(Button) findViewById(R.id.button1_main);
button1.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent = new Intent(MainActivity.this,NextActivity.class);
startActivityForResult(intent, BTN_ONE);
}
});

//监听button2，跳转到ThirdActivity，等待result
Button button2 =(Button) findViewById(R.id.button2_main);
button2.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent = new Intent(MainActivity.this,ThirdActivity.class);
startActivityForResult(intent, BTN_TWO);
}
});
}

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

public class NextActivity extends Activity
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_next);

Button button =(Button) findViewById(R.id.button1_next);
button.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
//得到用户数据
EditText editText=(EditText) findViewById(R.id.editText1_next);
String strone = editText.getText().toString();

//回传数据
Intent data = new Intent();
data.putExtra("one", strone);
setResult(1, data );

//关闭当前窗口
finish();
}
});
}

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

public class ThirdActivity extends Activity
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_third);Button button = (Button) findViewById(R.id.button1_third);
button.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
EditText editText = (EditText) findViewById(R.id.editText1_third);
String strtwo = editText.getText().toString();
Intent data = new Intent();
data.putExtra("two", strtwo);
setResult(2,data );
finish();
}
});
}@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.third, menu);
return true;
}
}