android 使用Intent传递数据之返回结果

我们开发应用时，不仅仅需要传递数据给其他activity，也要从其他activity中返回数据。

返回数据，我们一般采用Intent对象的方式来返回数据，采用这种方式，需要使用startActivityForResult方法来显式Activity，并且需要重写onActivityResult方法。

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {
private final int REQUESTCODE=1;//返回的结果码
private EditText one,two,three;
private Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

button = (Button)findViewById(R.id.button);
one = (EditText)findViewById(R.id.one);
two = (EditText)findViewById(R.id.two);
three=(EditText)findViewById(R.id.three);

button.setOnClickListener(new OnClickListener() {

public void onClick(View v) {
// TODO Auto-generated method stub

int a = Integer.parseInt(one.getText().toString());
int b = Integer.parseInt(two.getText().toString());
Intent intent = new Intent(MainActivity.this,OtherActivity.class);
intent.putExtra("a", a);
intent.putExtra("b", b);
startActivityForResult(intent, REQUESTCODE);//表示可以返回结果
}
});

}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);

if(resultCode==2){
if(requestCode==REQUESTCODE){
int request = data.getIntExtra("three", 0);//接收返回数据
three.setText(String.valueOf(request));
}
}

}

}

启动intent时，使用startActivityForResult方法
重写onActivityResult方法

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class OtherActivity extends Activity {

private Button button;
private TextView textview;
private EditText edittext;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.other);
button = (Button)findViewById(R.id.obutton);
textview = (TextView)findViewById(R.id.msg);
edittext = (EditText)findViewById(R.id.result);

Intent intent = getIntent();
int a = intent.getIntExtra("a", 0);
int b = intent.getIntExtra("b", 0);

textview.setText(a+" + "+b+" =   ?");

button.setOnClickListener(new OnClickListener() {

public void onClick(View v) {
// TODO Auto-generated method stub
int request = Integer.parseInt(edittext.getText().toString());
Intent intent = new Intent();
intent.putExtra("three", request);
//通过Intent对象返回结果，调用setResult方法
setResult(2,intent);
finish();//结束当前的activity的生命周期
}
});
}
}

/在另外一个activity中声明一个新的intent的，调用intent对象的setResult方法，并调用finish方法结束activity的生命周期。