Android Activity间传递自定义类的对象

有很多时候都需要在不同的Activity之间传递数据。
实现方法有很多，可以用Bundle来传递，也可以用给Intent用putExtra传递附加参数。
当然也可以传递自定义类的对象。为了让自定义类可以在Activity之间传递，必须符合一些条件。常用的方法是自定义类实现Parcelable接口或Serializable接口。Android中建议实现Parcelable。
下面例子中两种方法都有例子。
传递Parcelable过去，再传递Serializable回来。





WeightParcelable.java

import android.os.Parcel;
import android.os.Parcelable;

public class WeightParcelable implements Parcelable {
	private String sex;
	private double height;
//必须的空构造器，因为下面有一个私有的构造器，否则不能new对象
	public WeightParcelable() {

	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public double getHeight() {
		return height;
	}

	public void setHeight(double height) {
		this.height = height;
	}

	@Override
	public int describeContents() {
		return 0;
	}
//需要覆盖的方法
	@Override
	public void writeToParcel(Parcel out, int flags) {
		out.writeString(sex);
		out.writeDouble(height);
	}
//关键的事情
	public static final Parcelable.Creator<WeightParcelable> CREATOR = new Parcelable.Creator<WeightParcelable>() {
		public WeightParcelable createFromParcel(Parcel in) {
			return new WeightParcelable(in);
		}

		public WeightParcelable[] newArray(int size) {
			return new WeightParcelable[size];
		}
	};
//
	private WeightParcelable(Parcel in) {
		sex = in.readString();
		height = in.readDouble();
	}
}

HeightSerializable.java

import java.io.Serializable;

public class HeightSerializable implements Serializable {
	private static final long serialVersionUID = 8502706820090766507L;
	private String sex;
	private double weight;

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public double getWeight() {
		return weight;
	}

	public void setWeight(double weight) {
		this.weight = weight;
	}

}

EX03_10.java

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

public class EX03_10 extends Activity {
	/** Called when the activity is first created. */
	public static final String parcelableKey = "irdc.ex03_10.parcelableKey";
	public static final String seralizableKey = "irdc.ex03_10.seralizableKey";
	private static final String TAG = "EX03_10";

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		Button b1 = (Button) findViewById(R.id.button1);
		b1.setOnClickListener(new Button.OnClickListener() {
			public void onClick(View v) {
				EditText et = (EditText) findViewById(R.id.height);
				double height = Double.parseDouble(et.getText().toString());
				String sex = "";
				RadioButton rb1 = (RadioButton) findViewById(R.id.sex1);
				if (rb1.isChecked()) {
					sex = "M";
				} else {
					sex = "F";
				}
				Intent intent = new Intent();
				intent.setClass(EX03_10.this, EX03_10_1.class);

				Bundle bundle = new Bundle();

				WeightParcelable wp = new WeightParcelable();
				wp.setSex(sex);
				wp.setHeight((int) height);

				bundle.putParcelable(parcelableKey, wp);
				intent.putExtras(bundle);
//注意这里
				startActivityForResult(intent, 1);
			}
		});
	}
//这个是关键
	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		Log.d(TAG, "onActivityResult requestCode=" + requestCode
				+ " resultCode= " + resultCode + " data == null["
				+ (data == null) + "]");

		super.onActivityResult(requestCode, resultCode, data);
		if (requestCode == 1) {
			if (resultCode == RESULT_OK) {
				try {
					HeightSerializable hs = (HeightSerializable) data
							.getSerializableExtra(seralizableKey);

					TextView textView4 = (TextView) findViewById(R.id.text4);
					textView4.setText("性别：" + hs.getSex() + "\n标准体重:"
							+ hs.getWeight());

				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
	}

}

EX03_10_1.java

import java.text.DecimalFormat;
import java.text.NumberFormat;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class EX03_10_1 extends Activity {
	private static final String TAG = "EX03_10_1";

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.myalyout);

		WeightParcelable wp = (WeightParcelable) getIntent()
				.getParcelableExtra(EX03_10.parcelableKey);

		String sex = wp.getSex();
		double height = wp.getHeight();

		String sexText = "";
		if (sex.equals("M")) {
			sexText = "男性";
		} else {
			sexText = "女性";
		}

		String weight = this.getWeight(sex, height);

		TextView tv1 = (TextView) findViewById(R.id.text1);
		tv1.setText("性别:" + sexText + "\n身高:" + height + "厘米\n标准体重: " + weight
				+ "公斤");

		// 返回对象
		Intent data = new Intent();
		HeightSerializable hs = new HeightSerializable();
		hs.setSex(sexText);
		hs.setWeight(Double.valueOf(weight));

		data.putExtra(EX03_10.seralizableKey, hs);
//从这里返回对象
		setResult(RESULT_OK, data);
	}

	private String format(double num) {
		NumberFormat formatter = new DecimalFormat("0.00");
		String s = formatter.format(num);
		return s;
	}

	private String getWeight(String sex, double height) {
		String weight = "";
		if (sex.equals("M")) {
			weight = format((height - 80) * 0.7);
		} else {
			weight = format((height - 70) * 0.6);
		}
		return weight;
	}
}

评论

3 楼 GhostFromheaven 2011-05-21  

whao189 写道

我有个问题。。想 请教一下。。

是这样的

@Override 
    public void writeToParcel(Parcel out, int flags) {  
        out.writeString(sex);  
        out.writeDouble(height);  
    }  

private WeightParcelable(Parcel in) {  
        sex = in.readString();  
        height = in.readDouble();  
    }  


这个地方如果 sex height 的类型 都是一样 的 加入都是string 怎么 处理呢？？

你在readString 的 时候 Parcel会帮你 自动的  比对数据么？

希望楼主能指点一二！

可以都加入String.其实它内部是用map实现的，是key-value对。

2 楼 whao189 2011-05-19  

我有个问题。。想 请教一下。。

是这样的

@Override 
    public void writeToParcel(Parcel out, int flags) {  
        out.writeString(sex);  
        out.writeDouble(height);  
    }  

private WeightParcelable(Parcel in) {  
        sex = in.readString();  
        height = in.readDouble();  
    }  


这个地方如果 sex height 的类型 都是一样 的 加入都是string 怎么 处理呢？？

你在readString 的 时候 Parcel会帮你 自动的  比对数据么？

希望楼主能指点一二！

1 楼 windloverain 2010-12-01  

不错，学习了，一会试试。