Android入門：Intent入門

一、Intent與Activity應用

 

0.創建新的Activity步驟

 

在應用中創建新的Acitivity很常見；

步驟1：創建一個class繼承Activity

 

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

 

比如創建了一個名爲SubActivity的Activity，則需要聲明如下：

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

1.最簡單的跳轉到新的Activity

程序描述：MainActivity點擊按鈕後跳轉到SubActivity，MainActivity傳遞一個（name,xiazdong）給SubActivity，並獲得顯示；

 

效果如下：

 

點擊按鈕後：

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);  //從IntentActivity跳轉到SubActivity
intent.putExtra("name", "xiazdong");  //放入數據
startActivity(intent);  //開始跳轉
}
});
    }
}

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();    //獲得當前的Intent
  Bundle bundle = intent.getExtras();  //獲得全部數據
String value = bundle.getString("name");  //獲得名爲name的值
tv1.setText(value);
}


}

2.帶返回值的跳轉

 

跳轉到新的Activity並在結束後將返回值傳給原Activity

程序描述：MainActivity跳轉到SubActivity後，SubActivity執行完後返回一個結果碼給IntentActivity，執行對應的過程；

程序效果：

點擊跳轉後執行完第二個Activity後再跳回第一個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();  //創建一個Intent
intent.putExtra("response", "來自2");
setResult(200,intent);  //返回碼爲200
finish();
}


}