Android入门：Intent入门

一、Intent与Activity应用

 

0.创建新的Activity步骤

 

在应用中创建新的Acitivity很常见；

步骤1：创建一个class继承Activity

 

步骤2：在Android-manifest.xml中添加<activity>元素

 

比如创建了一个名为SubActivity的Activity，则需要声明如下：

        <activity android:name=".SubActivity"></activity>

1.最简单的跳转到新的Activity

程序描述：MainActivity点击按钮后跳转到SubActivity，MainActivity传递一个（name,xiazdong）给SubActivity，并获得显示；

 

效果如下：

 

点击按钮后：

IntentActivity.java

package org.xiazdong;


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;


public class IntentActivity extends Activity {
private Button btn1;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn1 = (Button)this.findViewById(R.id.brn1);
        btn1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setClass(IntentActivity.this, SubActivity.class);  //从IntentActivity跳转到SubActivity
intent.putExtra("name", "xiazdong");  //放入数据
startActivity(intent);  //开始跳转
}
});
    }
}

SubActivity.java

package org.xiazdong;


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


public class SubActivity extends Activity{
private TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.sub);
tv1 = (TextView)this.findViewById(R.id.tv1);
Intent intent = this.getIntent();    //获得当前的Intent
  Bundle bundle = intent.getExtras();  //获得全部数据
String value = bundle.getString("name");  //获得名为name的值
tv1.setText(value);
}


}

2.带返回值的跳转

 

跳转到新的Activity并在结束后将返回值传给原Activity

程序描述：MainActivity跳转到SubActivity后，SubActivity执行完后返回一个结果码给IntentActivity，执行对应的过程；

程序效果：

点击跳转后执行完第二个Activity后再跳回第一个Activity

IntentActivity.java

package org.xiazdong;


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.TextView;


public class IntentActivity extends Activity {
private Button btn1;
private TextView tv1;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn1 = (Button)this.findViewById(R.id.brn1);
        tv1 = (TextView)this.findViewById(R.id.tv2);
        btn1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setClass(IntentActivity.this, SubActivity.class);
startActivityForResult(intent, 100); //requestcode=100

}
});
    }
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode==100&&resultCode==200){
Bundle bundle = data.getExtras();
String response = bundle.getString("response");
tv1.setText(response);
}
}
    
}

SubActivity.java

package org.xiazdong;


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


public class SubActivity extends Activity{
private TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.sub);
tv1 = (TextView)this.findViewById(R.id.tv1);
Intent intent = new Intent();  //创建一个Intent
intent.putExtra("response", "来自2");
setResult(200,intent);  //返回码为200
finish();
}


}