建立二維數組
- 直接建立并指派:
int [][] array1 = {{1,2,3,4},{5,6,7,8},{9,10,11,12}};
- 指定大小進行建立
int [][] array2 = new int [4][8];//一邊聲明一邊配置設定記憶體
int [][] array3;
array3 = new int [4][8]; //先聲明再配置設定
//兩個for循環進行指派
列印二維數組
- 類似一維數組的Arrays.toString(),二維數組可以直接調用Arrays.deepToString()方法
/**
* 源碼
*/
public static String deepToString(Object[] a) {
if (a == null)
return "null";
int bufLen = 20 * a.length;
if (a.length != 0 && bufLen <= 0)
bufLen = Integer.MAX_VALUE;
StringBuilder buf = new StringBuilder(bufLen);
deepToString(a, buf, new HashSet<>());
return buf.toString();
}
private static void deepToString(Object[] a, StringBuilder buf,
Set<Object[]> dejaVu) {
if (a == null) {
buf.append("null");
return;
}
int iMax = a.length - 1;
if (iMax == -1) {
buf.append("[]");
return;
}
dejaVu.add(a);
buf.append('[');
for (int i = 0; ; i++) {
Object element = a[i];
if (element == null) {
buf.append("null");
} else {
Class<?> eClass = element.getClass();
if (eClass.isArray()) {
if (eClass == byte[].class)
buf.append(toString((byte[]) element));
else if (eClass == short[].class)
buf.append(toString((short[]) element));
else if (eClass == int[].class)
buf.append(toString((int[]) element));
else if (eClass == long[].class)
buf.append(toString((long[]) element));
else if (eClass == char[].class)
buf.append(toString((char[]) element));
else if (eClass == float[].class)
buf.append(toString((float[]) element));
else if (eClass == double[].class)
buf.append(toString((double[]) element));
else if (eClass == boolean[].class)
buf.append(toString((boolean[]) element));
else { // element is an array of object references
if (dejaVu.contains(element))
buf.append("[...]");
else
deepToString((Object[])element, buf, dejaVu);
}
} else { // element is non-null and not an array
buf.append(element.toString());
}
}
if (i == iMax)
break;
buf.append(", ");
}
buf.append(']');
dejaVu.remove(a);
}
- for循環列印
//簡寫一下,就這意思 自己修飾下加個括号啥的
for (i = 0; i < row; i++){
for (j = 0; j < col; j++){
//print(arr[i][j]);
}
}
//也可以隻用一個for 稍微優化一點
for (int i = 0, j = 0; i < a.length;) {
System.out.print(a[i][j] +" ");
j++;
if (j >= a[i].length) {
i++;
j = 0;
}
}
好多東西不常用都忘記了,記錄一下防止遺忘
感謝看到這裡~