保持第一个activity的数据

最新推荐文章于 2025-07-06 18:40:25 发布

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#Intent Bundle

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本文介绍了一种在Android应用中不同Activity间传递数据的方法。通过Intent和Bundle实现了从一个Activity向另一个Activity发送数据，并展示了如何在目标Activity中解析并使用这些数据。此外，还介绍了两种实现方式：一种是直接启动目标Activity并传递数据；另一种是使用startActivityForResult进行数据请求及回调。

1，在一个activity里传入数据(通过intent.putExtras(bundle))

2，返回时，主activity里通过再次调用this.getIntent().getExtras()获取bundle值，来显示原先的值

package irdc.ex03_10;
/* import相关class */ 
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;

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;
public class EX03_10 extends Activity 
{ 
  private static final String TAG = "EX03_10_1";
  EditText et;
  double height;
  RadioButton rb1;
  RadioButton rb2;
  String sex="";
  
  /** Called when the activity is first created. */ 
  @Override
  public void onCreate(Bundle savedInstanceState)
  { 
    super.onCreate(savedInstanceState); 
    /* 载入main.xml Layout */
    setContentView(R.layout.main); 
    et = (EditText) findViewById(R.id.height);
    rb1 = (RadioButton) findViewById(R.id.sex1);
    rb2 = (RadioButton) findViewById(R.id.sex2);
    Bundle bunde = this.getIntent().getExtras();
    if(bunde != null){
      Log.i(TAG," bunde " + bunde);
      height = bunde.getDouble("height");
      et.setText(""+height);
      if(sex.equals("M")){
        rb1.setChecked(true);
      }else{
        rb2.setChecked(true);
      }
    }
    /* 以findViewById()取得Button对象，并加入onClickListener */ 
    Button b1 = (Button) findViewById(R.id.button1);
    b1.setOnClickListener(new Button.OnClickListener() 
    {
      public void onClick(View v) 
      {
        /*取得输入的身高*/ 
        
        height=Double.parseDouble(et.getText().toString()); 
        /*取得选择的性别*/ String sex=""; 
        
        if(rb1.isChecked()) { sex="M"; }
        else{ sex="F"; } 
        /*new一个Intent对象，并指定class*/
        Intent intent = new Intent(); 
        intent.setClass(EX03_10.this,EX03_10_1.class); 
        /*new一个Bundle对象，并将要传递的数据传入*/
       /* String[] str = new String[]{"1","2","3"};
        ArrayList<String> arr = new ArrayList<String>();
        arr.add("One");
        arr.add("Two");
        arr.add("Three");*/
        Bundle bundle = new Bundle();
        bundle.putDouble("height",height);
        bundle.putString("sex",sex); 
        
       /* bundle.putStringArrayList("1",arr);
        bundle.putStringArray("2", str);*/
        /*将Bundle对象assign给Intent*/ 
        intent.putExtras(bundle); 
        /*调用Activity EX03_10_1*/ 
        startActivity(intent); 
        } 
      }); 
    }
  }

package irdc.ex03_10;

/* import相关class */
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.ArrayList;

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

public class EX03_10_1 extends Activity 
{
  private static final String TAG = "EX03_10_1";
  Bundle bunde;
  Intent intent;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    /* 加载main.xml Layout */
    setContentView(R.layout.myalyout);
    
    if(savedInstanceState != null){
      
    }
    
    Button bt = (Button) findViewById(R.id.btnBt);
    intent = new Intent();
   
    
    /* 取得Intent中的Bundle对象 */
    bunde = this.getIntent().getExtras();
    
    /* 取得Bundle对象中的数据 */
    StringBuffer sb = new StringBuffer();;
    String sex = bunde.getString("sex");
    double height = bunde.getDouble("height");
    /*ArrayList<String> arr = bunde.getStringArrayList("1");
    String[] aStr = bunde.getStringArray("2");*/
    /*判断性别 */
    String sexText="";
    if(sex.equals("M")){
      sexText="男性";
    }else{
      sexText="女性";
    }
    
    /* 取得标准体重 */
    String weight=this.getWeight(sex, height);
    
    /* 设定输出文字 */
    TextView tv1=(TextView) findViewById(R.id.text1);
    
  /*  for(int i=0;i<aStr.length;i++){
       sb = sb.append(aStr[i]);   
    }*/
    
    bt.setOnClickListener(new OnClickListener()
    {
      @Override
      public void onClick(View v)
      {
        // TODO Auto-generated method stub
        intent.setClass(EX03_10_1.this,EX03_10.class);
        intent.putExtras(bunde);
        startActivity(intent);
      }
      
    });
    tv1.setText("你是一位"+sexText+"\n你的身高是"+height+
                "公分\n你的标准体重是"+weight+"公斤" /*+ "\n" + arr + "\n" + sb*/);
  }
  
  /* 四舍五入的method */
  private String format(double num)
  {
    NumberFormat formatter = new DecimalFormat("0.00");
    String s=formatter.format(num);
  return s;
  }

  /* 以findViewById()取得Button对象，onClickListener */  
  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;
  }
}

也可以有第2种方式来实现：由startActivityForResult来实现

package irdc.ex03_11; /* import相关class */

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.RadioButton;

public class EX03_11 extends Activity
{
  private EditText et;
  private RadioButton rb1;
  private RadioButton rb2;

  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState); /* 加载main.xml Layout */
    setContentView(R.layout.main); /*
                                    * 以findViewById()取得Button对象，并加入onClickListener
                                    */
    Button b1 = (Button) findViewById(R.id.button1);
    b1.setOnClickListener(new Button.OnClickListener()
    {
      public void onClick(View v)
      { /* 取得输入的身高 */
        et = (EditText) findViewById(R.id.height);
        double height = Double.parseDouble(et.getText().toString()); /* 取得选择的性别 */
        String sex = "";
        rb1 = (RadioButton) findViewById(R.id.sex1);
        rb2 = (RadioButton) findViewById(R.id.sex2);
        if (rb1.isChecked())
        {
          sex = "M";
        } else
        {
          sex = "F";
        } /* new一个Intent对象，并指定class */
        Intent intent = new Intent();
        intent.setClass(EX03_11.this, EX03_11_1.class); /*
                                                         * new一个Bundle对象，并将要传递的数据传入
                                                         */
        Bundle bundle = new Bundle();
        bundle.putDouble("height", height);
        bundle.putString("sex", sex); /* 将Bundle对象assign给Intent */
        intent.putExtras(bundle); /* 调用Activity EX03_11_1 */
        startActivityForResult(intent, 0);
      }
    });
  } /* 重写 onActivityResult() */

  @Override
  protected void onActivityResult(int requestCode, int resultCode,
      Intent data)
  {
    switch (resultCode)
    {
      case RESULT_OK: /* 取得数据，并显示于画面上 */
        Bundle bunde = data.getExtras();
        String sex = bunde.getString("sex");
        double height = bunde.getDouble("height");
        et.setText("" + height);
        if (sex.equals("M"))
        {
          rb1.setChecked(true);
        } else
        {
          rb2.setChecked(true);
        }
        break;
      default:
        break;
    }
  }
}

package irdc.ex03_11; /* import相关class */

import java.text.DecimalFormat;
import java.text.NumberFormat;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class EX03_11_1 extends Activity
{
  Bundle bunde;
  Intent intent;

  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState); /* 载入mylayout.xml Layout */
    setContentView(R.layout.myalyout); /* 取得Intent中的Bundle对象 */
    intent = this.getIntent();
    bunde = intent.getExtras(); /* 取得Bundle对象中的数据 */
    String sex = bunde.getString("sex");
    double height = bunde.getDouble("height"); /* 判断性别 */
    String sexText = "";
    if (sex.equals("M"))
    {
      sexText = "男性";
    } else
    {
      sexText = "女性";
    } /* 取得标准体重 */
    String weight = this.getWeight(sex, height); /* 设定输出文字 */
    TextView tv1 = (TextView) findViewById(R.id.text1);
    tv1.setText("你是一位" + sexText + "\n你的身高是" + height + "公分\n你的标准体重是"
        + weight + "公斤"); /* 以findViewById()取得Button对象，并加入onClickListener */
    Button b1 = (Button) findViewById(R.id.button1);
    b1.setOnClickListener(new Button.OnClickListener()
    {
      public void onClick(View v)
      { /* 回传result回上一个activity */
        EX03_11_1.this.setResult(RESULT_OK, intent); /* 关闭activity */
        EX03_11_1.this.finish();
      }
    });
  } /* 四舍五入的method */

  private String format(double num)
  {
    NumberFormat formatter = new DecimalFormat("0.00");
    String s = formatter.format(num);
    return s;
  } /* 以findViewById()取得Button对象，并加入onClickListener */

  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;
  }
}