Android 数据传递-从Activity中返回数据

Ø在实际的应用中，我们不仅仅要向Activity传递数据，而且要从Activity中返回数据，虽然返回数据和传递数据类似，也可以采用前面4种方法，但是一般建议采用Intent对象的方式来返回数据，使用这种方式返回数据，需要使用startActivityForResult方法来显示Activity。

 

Ø案例一

 

package com.android.myintent;

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

public class Main extends Activity {
	/** Called when the activity is first created. */
	private Button button;
	private final static int REQUESTCODE = 1;//返回的结果码
    private EditText one,two,result;
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		button = (Button) this.findViewById(R.id.button);
		one = (EditText)this.findViewById(R.id.one);
		two = (EditText)this.findViewById(R.id.two);
		result = (EditText)this.findViewById(R.id.result);
		button.setOnClickListener(new View.OnClickListener() {
        
			@Override
			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(Main.this, OtherActivity.class);
				intent.putExtra("a", a);
				intent.putExtra("b", b);
				//启动Intent
				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 three = data.getIntExtra("three", 0);
				result.setText(String.valueOf(three));
			}
		}
	}
}

 

 

package com.android.myintent;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
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)this.findViewById(R.id.button2);
		textView = (TextView)this.findViewById(R.id.msg);
		editText = (EditText)this.findViewById(R.id.three);
		Intent intent = getIntent();
		int a = intent.getIntExtra("a", 0);
		int b = intent.getIntExtra("b", 0);
		textView.setText(a+" + "+b+" = "+" ? ");
		button.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
			   Intent intent = new Intent();
			   int three = Integer.parseInt(editText.getText().toString());
			   intent.putExtra("three", three);
			   //通过Intent对象返回结果，setResult方法，
			   setResult(2, intent);
			   finish();//结束当前的Activity的生命周期。
			}
		});
	}
}