Android 四大組件

1、使用Intent對象來指定一個Activity,並通過startActivity或startActivityForResult方法啟動該Activity.以及在Activity之間傳遞數據：

1. public class MainActivity extends Activity {
3. private Button btn1,btn2;
4. @Override
5. public void onCreate(Bundle savedInstanceState) {
6. super.onCreate(savedInstanceState);
7. LinearLayout view = new LinearLayout(this);
8. view.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
10. btn1 = new Button(this);
11. btn1.setId(1);
12. btn1.setText("使用類名開啟另一個Activity");
13. btn1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
15. btn2 = new Button(this);
16. btn2.setId(2);
17. btn2.setText("使用action開啟另一個Activity");
18. btn2.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
20. view.addView(btn1);
21. view.addView(btn2);
22. setContentView(view);
24. btn1.setOnClickListener(listener);
25. btn2.setOnClickListener(listener);
26. }
28. private View.OnClickListener listener = new OnClickListener() {
29. @Override
30. public void onClick(View view) {
31. Intent intent = new Intent();
32. switch (view.getId()) {
33. case 1:
34. intent.setClass(MainActivity.this, ResultActivity.class);
35. intent.putExtra("name", "JAVA");
36. startActivityForResult(intent, 222);
37. break;
38. case 2:
39. intent.setAction("forResult");
40. MyData myData = new MyData();
41. //使用putExtra傳遞自定義對象時，該對象必須實現序列化，該類中的所有成員屬性也必須實現序列化接口
42. intent.putExtra("data", myData);
43. startActivity(intent);
44. break;
45. default:
46. break;
47. }
48. }
49. };
53. @Override
54. protected void onActivityResult(int requestCode, int resultCode, Intent data) {
55. //requestCode是請求碼，即startActivityForResult(intent, 222)中的第二個參數
56. //resultCode是結果碼，即setResult(333)中設置的數字
57. switch (requestCode) {
58. case 222:
59. if(resultCode == 333){
60. Toast.makeText(this, "無結果返回...", Toast.LENGTH_LONG).show();
61. } else if(resultCode == 444){
62. Toast.makeText(this, data.getStringExtra("result"), Toast.LENGTH_LONG).show();
63. }
64. break;
65. default:
66. break;
67. }
68. }
69. }

1. public class ResultActivity extends Activity {
2. private Button btn1 , btn2;
3. private TextView tv;
4. private Intent intent;
5. @Override
6. protected void onCreate(Bundle savedInstanceState) {
7. // TODO Auto-generated method stub
8. super.onCreate(savedInstanceState);
10. intent = getIntent();
12. LinearLayout view = new LinearLayout(this);
13. view.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
14. LayoutParams.FILL_PARENT));
16. tv = new TextView(this);
17. tv.setText("name is "+intent.getStringExtra("name"));
18. tv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
19. LayoutParams.WRAP_CONTENT));
21. btn1 = new Button(this);
22. btn1.setId(1);
23. btn1.setText("Back1");
24. btn1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
25. LayoutParams.WRAP_CONTENT));
27. btn2 = new Button(this);
28. btn2.setId(2);
29. btn2.setText("Back2");
30. btn2.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
31. LayoutParams.WRAP_CONTENT));
33. view.addView(tv);
34. view.addView(btn1);
35. view.addView(btn2);
37. btn1.setOnClickListener(listener);
38. btn2.setOnClickListener(listener);
39. setContentView(view);
40. }
42. private View.OnClickListener listener = new OnClickListener() {
43. @Override
44. public void onClick(View view) {
45. switch (view.getId()) {
46. case 1:
47. setResult(333);
48. break;
49. case 2:
50. intent.putExtra("result", "帶結果返回");
51. setResult(444, intent);
52. break;
53. default:
54. break;
55. }
56. ResultActivity.this.finish();
57. }
58. };
60. }

1. public class Result2Activity extends Activity {
2. @Override
3. protected void onCreate(Bundle savedInstanceState) {
4. super.onCreate(savedInstanceState);
5. setContentView(R.layout.main);
6. MyData data = (MyData)getIntent().getSerializableExtra("data");
7. setTitle(data.value);
8. }
9. }

1. public class MyData implements Serializable {
2. public String value = "this is test";
3. }

2、Intent指定Activity的方式

2.1 直接使用Class

code :

intent.setClass(MainActivity.this, ResultActivity.class);

manifest :

<activity Android:name=".ResultActivity"></activity>

2.2 使用Action

code :

intent.setAction("forResult");

manifest :

<activity android:name=".Result2Activity">
<intent-filter>
<action android:name="forResult"></action>
<category android:name="android.intent.category.DEFAULT"></category>
</intent-filter>
</activity>

2.3 使用包名

code :

ComponentName cn = new ComponentName(MainActivity.this, "com.zj.activity.another.ActivityA");

intent.setComponent(cn);

manifest:

<activity android:name=".another.ActivityA"></activity>