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。