Question

我正在尝试制作一个应用，我想要在其中将值从editText(MainActivity.java)传递到放置在另一个活动中的listView(bestFitActivity.java)。我的代码的问题在于，它仅将一个值传递给listView。输入新值时，它将替换先前的值。

MainActivity.java

public class MainActivity extends AppCompatActivity {
    int i = 0;
    String getChunkSize;
    ArrayList<String> chunkSizeArray = new ArrayList<>();
    EditText chunkSize;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button chunkSave = (Button)findViewById(R.id.chunkSave);
        Button processSave = (Button)findViewById(R.id.processSave);
        Button bestFitDirector = (Button)findViewById(R.id.bestFitdirector);
        Button worstFitDirector = (Button)findViewById(R.id.worstFitdirector);
        Button firstFitDirector = (Button)findViewById(R.id.firstFitDirector);

        EditText processSize = (EditText)findViewById(R.id.processSize);
        chunkSize = (EditText)findViewById(R.id.chunkSize);

        chunkSave.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                i++;
                Log.d("Manager" , "%d" +i);


                getChunkSize = chunkSize.getText().toString();
                //Log.d("Manager" , "" +getChunkSize);


                if(getChunkSize == null ) {
                    Toast.makeText(getBaseContext(), "Empty Input", Toast.LENGTH_SHORT).show();
                }
            }
        });

        bestFitDirector.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent myIntent =  new Intent(MainActivity.this , bestFitActivity.class);
                myIntent.putExtra("chunkSizeArray" , getChunkSize );
                startActivity(myIntent);
            }
        });

        /*worstFitDirector.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent myIntent2 = new Intent (MainActivity.this , worstFitActivity.class);
                startActivity(myIntent2);
            }
        });

        firstFitDirector.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent myIntent3 = new Intent (MainActivity.this , firstFitActivity.class);
                startActivity(myIntent3);
            }

        });*/
    }
}

bestFitActivity.java

public class bestFitActivity extends AppCompatActivity {
    String chunkSIZE;
    ArrayList<String> chunkSizeArray = new ArrayList<>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_best_fit);

        ListView blockSize = (ListView)findViewById(R.id.blockSize);
        ListView finalProcessList  = (ListView)findViewById(R.id.finalprocesslist);

        chunkSIZE = getIntent().getExtras().getString("chunkSizeArray");
        Log.d("Manager" , " "+chunkSIZE);

        chunkSizeArray.add(chunkSIZE);
        Log.d("Manager" , ""+chunkSIZE);

        ArrayAdapter<String> adapter = new ArrayAdapter<>(bestFitActivity.this , android.R.layout.simple_expandable_list_item_1 , chunkSizeArray);
        blockSize.setAdapter(adapter);
        adapter.notifyDataSetChanged();
        //((EditText)findViewById(R.id.chunkSize)).setText(" ");
        //EditText tv = (EditText) findviewbyID(R.id.)
    }
}

PS：该代码不完整

Answer 1

每次单击按钮时，都会使用一个值创建一个新的活动，其中包含一个新的空chunkSize ArrayList。

您可以在每次单击按钮时将其添加到MainActivity中的 chunkSizeArray ，然后在单个intentExtras中发送一个计数器和该数组的值。

然后从bestFitActivity中的所有意向中检索并构建ArrayList。

这是您可以做到的

public class MainActivity extends AppCompatActivity {

    public static final String INTENTKEY_ARRAYELEMENTS = "arrayelemets";
    public static final String INTENYKEY_ELEMENTX = "element_";
    private static ArrayList<String> chunkSizeArray = new ArrayList<>();
    Button bestFitDirector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bestFitDirector = (Button)findViewById(R.id.bestFitdirector);

        bestFitDirector.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                chunkSizeArray.add("Test" + String.valueOf(chunkSizeArray.size() + 1));
                Intent myitent = new Intent(MainActivity.this,bestFitActivity.class);
                myitent.putExtra(INTENTKEY_ARRAYELEMENTS, chunkSizeArray.size());
                for (int i=0; i < chunkSizeArray.size(); i++) {
                    myitent.putExtra(INTENYKEY_ELEMENTX + String.valueOf(i),chunkSizeArray.get(i));
                }
                startActivity(myitent);
            }
        });
    }
}

和

public class bestFitActivity extends AppCompatActivity {

    ArrayList<String> chunkSizeArray = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_best_fit);

        Intent mypassedIntent = getIntent();

        int elements = mypassedIntent.getIntExtra(MainActivity.INTENTKEY_ARRAYELEMENTS,0);
        for (int i = 0; i < elements; i++) {
            chunkSizeArray.add(mypassedIntent.getStringExtra(MainActivity.INTENYKEY_ELEMENTX + String.valueOf(i)));
        }
        Toast.makeText(this,"The number of strings in the chukSizeArray is " + String.valueOf(chunkSizeArray.size()),Toast.LENGTH_SHORT).show();
        for (String s: chunkSizeArray) {
            Log.d("chunkSizeArray Value",s);
        }
    }
}

单击5次（单击返回以返回MainActivity）后，日志为

2019-03-10 17:19:51.687 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test1

2019-03-10 17:19:56.362 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test1
2019-03-10 17:19:56.362 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test2

2019-03-10 17:19:59.877 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test1
2019-03-10 17:19:59.877 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test2
2019-03-10 17:19:59.877 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test3

2019-03-10 17:20:03.007 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test1
2019-03-10 17:20:03.007 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test2
2019-03-10 17:20:03.007 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test3
2019-03-10 17:20:03.007 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test4

2019-03-10 17:20:06.266 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test1
2019-03-10 17:20:06.266 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test2
2019-03-10 17:20:06.266 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test3
2019-03-10 17:20:06.266 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test4
2019-03-10 17:20:06.266 11271-11271/com.example.bestfitapp D/chunkSizeArray Value: Test5

添加了空白以使点击次数增加

一种更简单的方法是将 putStringArrayListExtra 与 getStringArrayListExtra 方法一起使用，该方法基本上代表您执行循环。

因此主要活动具有

 public static final String INTENTKEY_ARRAY = "bestfitarray";

在onClick侦听器中，您可以：-

myitent.putStringArrayListExtra(INTENTKEY_ARRAY,chunkSizeArray);

随

myitent.putStringArrayListExtra(INTENTKEY_ARRAY,chunkSizeArray);

在bestFitActivity中。

将项目添加到另一个活动中的列表视图（仅添加1个条目）

1 个答案: